Download Topic 10 SL Mark Scheme Past exam paper questions

IB CHEMISTRY GUIDE
Topic 10 & 20
Organic chemistry
Syllabus:
10.1 Fundamentals of organic chemistry
Understandings:
•
A homologous series is a series of compounds of the same family, with the same general formula,
which differ from each other by a common structural unit.
•
Structural formulas can be represented in full and condensed format.
•
Structural isomers are compounds with the same molecular formula but different arrangements of
atoms.
•
Functional groups are the reactive parts of molecules.
•
Saturated compounds contain single bonds only and unsaturated compounds contain double or triple
bonds.
•
Benzene is an aromatic, unsaturated hydrocarbon.
Applications and skills:
• Explanation of the trends in boiling points of members of a homologous series.
• Distinction between empirical, molecular and structural formulas.
• Identification of different classes: alkanes, alkenes, alkynes, halogenoalkanes, alcohols, ethers,
aldehydes, ketones, esters, carboxylic acids, amines, amides, nitriles and arenes.
• Identification of typical functional groups in molecules eg phenyl, hydroxyl, carbonyl, carboxyl,
carboxamide, aldehyde, ester, ether, amine, nitrile, alkyl, alkenyl and alkynyl.
• Construction of 3-D models (real or virtual) of organic molecules.
• Application of IUPAC rules in the nomenclature of straight-chain and branched- chain isomers.
• Identification of primary, secondary and tertiary carbon atoms in halogenoalkanes and alcohols and
primary, secondary and tertiary nitrogen atoms in amines.
• Discussion of the structure of benzene using physical and chemical evidence.
Guidance:
•
Skeletal formulas should be discussed in the course.
•
The general formulas (eg CnH2n+2) of alkanes, alkenes, alkynes, ketones, alcohols, aldehydes and
carboxylic acids should be known.
•
The distinction between class names and functional group names needs to be made. Eg for OH,
hydroxyl is the functional group whereas alcohol is the class name.
•
The following nomenclature should be covered:
- non-cyclic alkanes and halogenoalkanes up to halohexanes.
- alkenes up to hexene and alkynes up to hexyne.
- compounds up to six carbon atoms (in the basic chain for nomenclature purposes) containing only
one of the classes of functional groups: alcohols, ethers, aldehydes, halogenoalkanes, ketones,
esters and carboxylic acids.
10.2 Electrochemical cells
Understandings:
Alkanes:
P a g e |2
IB Chemistry - Topic 10 and 20 Guide
•
Alkanes have low reactivity and undergo free-radical substitution reactions.
Alkenes:
•
Alkenes are more reactive than alkanes and undergo addition reactions. Bromine water can be used to
distinguish between alkenes and alkanes.
Alcohols:
•
Alcohols undergo nucleophilic substitution reactions with acids (also called esterification or
condensation) and some undergo oxidation reactions.
Halogenoalkanes:
•
Halogenoalkanes are more reactive than alkanes. They can undergo (nucleophilic) substitution
reactions. A nucleophile is an electron-rich species containing a lone pair that it donates to an
electron-deficient carbon.
Polymers:
•
Addition polymers consist of a wide range of monomers and form the basis of the plastics industry.
Benzene:
•
Benzene does not readily undergo addition reactions but does undergo electrophilic substitution
reactions.
Applications and skills:
Alkanes:
•
Writing equations for the complete and incomplete combustion of hydrocarbons.
•
Explanation of the reaction of methane and ethane with halogens in terms of a free-radical
substitution mechanism involving photochemical homolytic fission.
Alkenes:
•
Writing equations for the reactions of alkenes with hydrogen and halogens and of symmetrical
alkenes with hydrogen halides and water.
•
Outline of the addition polymerization of alkenes.
•
Relationship between the structure of the monomer to the polymer and repeating unit.
Alcohols:
•
Writing equations for the complete combustion of alcohols.
•
Writing equations for the oxidation reactions of primary and secondary alcohols (using acidified
potassium dichromate(VI) or potassium manganate(VII) as oxidizing agents). Explanation of
distillation and reflux in the isolation of the aldehyde and carboxylic acid products.
•
Writing the equation for the condensation reaction of an alcohol with a carboxylic acid, in the
presence of a catalyst (eg concentrated sulfuric acid) to form an ester.
Halogenoalkanes:
•
Writing the equation for the substitution reactions of halogenoalkanes with aqueous sodium
hydroxide.
Guidance:
•
Reference should be made to initiation, propagation and termination steps in free-radical substitution
reactions. Free radicals should be represented by a single dot.
•
The mechanisms of SN1 and SN2 and electrophilic substitution reactions are not required.
20.1 Types of organic reactions
Understandings:
Nucleophilic Substitution Reactions:
•
SN1 represents a nucleophilic unimolecular substitution reaction and SN2 represents a nucleophilic
bimolecular substitution reaction. SN1 involves a carbocation intermediate. SN2 involves a concerted
reaction with a transition state.
•
For tertiary halogenoalkanes the predominant mechanism is SN1 and for primary halogenoalkanes it
P a g e |3
IB Chemistry - Topic 10 and 20 Guide
is SN2. Both mechanisms occur for secondary halogenoalkanes.
•
The rate determining step (slow step) in an SN1 reaction depends only on the concentration of the
halogenoalkane, rate = k[halogenoalkane]. For SN2, rate = k[halogenoalkane][nucleophile]. SN2 is
stereospecific with an inversion of configuration at the carbon.
•
SN2 reactions are best conducted using aprotic, non-polar solvents and SN1 reactions are best
conducted using protic, polar solvents.
Electrophilic Addition Reactions:
•
An electrophile is an electron-deficient species that can accept electron pairs from a nucleophile.
Electrophiles are Lewis acids.
•
Markovnikov’s rule can be applied to predict the major product in electrophilic addition reactions of
unsymmetrical alkenes with hydrogen halides and interhalogens. The formation of the major product
can be explained in terms of the relative stability of possible carbocations in the reaction mechanism.
Electrophilic Substitution Reactions:
•
Benzene is the simplest aromatic hydrocarbon compound (or arene) and has a delocalized structure of
n bonds around its ring. Each carbon to carbon bond has a bond order of 1.5. Benzene is susceptible to
attack by electrophiles.
Reduction Reactions:
•
Carboxylic acids can be reduced to primary alcohols (via the aldehyde). Ketones can be reduced to
secondary alcohols. Typical reducing agents are lithium aluminium hydride (used to reduce
carboxylic acids) and sodium borohydride.
Applications and skills:
Nucleophilic Substitution Reactions:
•
Explanation of why hydroxide is a better nucleophile than water.
•
Deduction of the mechanism of the nucleophilic substitution reactions of halogenoalkanes with
aqueous sodium hydroxide in terms of SN1 and SN2 mechanisms. Explanation of how the rate
depends on the identity of the halogen (ie the leaving group), whether the halogenoalkane is primary,
secondary or tertiary and the choice of solvent.
•
Outline of the difference between protic and aprotic solvents.
Electrophilic Addition Reactions:
•
Deduction of the mechanism of the electrophilic addition reactions of alkenes with
halogens/interhalogens and hydrogen halides.
Electrophilic Substitution Reactions:
•
Deduction of the mechanism of the nitration (electrophilic substitution) reaction of benzene (using a
mixture of concentrated nitric acid and sulfuric acid).
Reduction Reactions:
•
Writing reduction reactions of carbonyl containing compounds: aldehydes and ketones to primary
and secondary alcohols and carboxylic acids to aldehydes, using suitable reducing agents.
•
Conversion of nitrobenzene to phenylamine via a two-stage reaction.
Guidance:
•
Reference should be made to heterolytic fission for SN1 reactions.
•
The difference between homolytic and heterolytic fission should be understood.
•
The difference between curly arrows and fish-hooks in reaction mechanisms should be emphasized.
•
Use of partial charges (6+ and 6-) and wedge-dash three-dimensional representations (using tapered
bonds as shown below) should be encouraged where appropriate in explaining reaction mechanisms.
P a g e |4
IB Chemistry - Topic 10 and 20 Guide
•
Typical conditions and reagents of all reactions should be known (eg catalysts, reducing agents,
reflux etc.). However, more precise details such as specific temperatures need not be included.
20.2 Synthetic routes
Understandings:
•
The synthesis of an organic compound stems from a readily available starting material via a series of
discrete steps. Functional group interconversions are the basis of such synthetic routes.
•
Retro-synthesis of organic compounds.
Applications and skills:
• Deduction of multi-step synthetic routes given starting reagents and the product(s).
Guidance:
•
Conversions with more than four stages will not be assessed in synthetic routes.
•
Reaction types can cover any of the reactions covered in topic 10 and sub-topic 20.1.
20.3 Stereoisomerism
Understandings:
•
Stereoisomers are subdivided into two classes—conformational isomers, which interconvert by
rotation about a o bond and configurational isomers that interconvert only by breaking and reforming
a bond.
Configurational isomers are further subdivided into cis-trans and E/Z isomers and optical isomers.
•
•
•
Cis-trans isomers can occur in alkenes or cycloalkanes (or heteroanalogues) and differ in the positions
of atoms (or groups) relative to a reference plane. According to IUPAC, E/Z isomers refer to alkenes
of the form R1R2C=CR3R4 (R1 / R2, R3 / R4) where neither R1 nor R2 need be different from R3
or R4.
A chiral carbon is a carbon joined to four different atoms or groups.
An optically active compound can rotate the plane of polarized light as it passes through a solution of
the compound. Optical isomers are enantiomers. Enantiomers are non-superimposeable mirror images
P a g e |5
IB Chemistry - Topic 10 and 20 Guide
•
of each other. Diastereomers are not mirror images of each other.
A racemic mixture (or racemate) is a mixture of two enantiomers in equal amounts and is optically
inactive.
Applications and skills:
• Construction of 3-D models (real or virtual) of a wide range of stereoisomers.
• Explanation of stereoisomerism in non-cyclic alkenes and C3 and C4 cycloalkanes.
• Comparison between the physical and chemical properties of enantiomers.
• Description and explanation of optical isomers in simple organic molecules.
• Distinction between optical isomers using a polarimeter.
Guidance:
•
The term geometric isomers as recommended by IUPAC is now obsolete and cis-trans isomers and
E/Z isomers should be encouraged in the teaching programme.
•
In the E/Z system, the group of highest Cahn–Ingold–Prelog priority attached to one of the terminal
doubly bonded atoms of the alkene (ie R1 or R2) is compared with the group of highest precedence
attached to the other (ie R3 or R4). The stereoisomer is Z if the groups lie on the same side of a
reference plane passing through the double bond and perpendicular to the plane containing the bonds
linking the groups to the double-bonded atoms; the other stereoisomer is designated as E.
•
Wedge-dash type representations involving tapered bonds should be used for representations of
optical isomers.
P a g e |6
IB Chemistry - Topic 10 and 20 Guide
Notes:
The following is the minimum that should be in your course notes.
Topic 10 (SL):
Introduction
Definitions of: Empirical, molecular and structural formula, structural isomers, primary, secondary and
tertiary carbon atoms with examples.
Examples of how to name non-cyclic organic compounds from structural drawings and vice-versa, with
chains of up to 6 carbon atoms with one of the following functional groups: (alkane), alkene, alcohol,
aldehyde, ketone, carboxylic acid and halide.
Examples of compounds containing amino, benzene ring (phenyl) and ester functional groups.
Describe the volatility and solubility in water of compounds containing the functional groups: alcohol,
aldehyde, ketone, carboxylic acid and halide.
Alkanes
Definition of: homologous series, free-radical.
Explanation of the trend in boiling point along a series.
Explanation of the (un)reactivity of alkanes.
Examples of complete and incomplete combustion reactions of alkanes.
Explanation and example of the reaction of an alkane with chlorine or bromine to produce a mixture of
haloalkanes with all steps in mechanism shown and named.
Alkenes
Definition of: electrophile, electrophillic addition.
Statement of how to test for C=C or CC.
Examples of mechanisms of electrophillic addition of alkenes with H2, HBr, Br2, H2O.
Explanation of reasons why alkenes show this mechanism.
Examples of products formed from the polymerisation of ethene, chloroethene and propene monomers and
vice versa.
Statement of the industrial uses of the hydrogenation, hydration and polymerisation reactions of alkenes.
Alcohols
Examples of equations for the complete combustion of alcohols.
Examples of equations and conditions for the oxidation of alcohols to aldehydes, ketones and carboxylic
acids.
Haloalkanes
Definitions of: nucleophillic, substitution.
Example of the mechanism of nucleophillic substitution by OH-, on haloalkanes.
Reaction Pathways
Examples of two step reaction pathways with reagents, conditions and equations through the scheme below
e.g. the conversion of but-2-ene to butanone can be done in two stages: but-2-ene can be heated with steam
and a catalyst to form butan-2-ol, which can then be oxidized by heating with acidified potassium
dichromate(VI) to form butanone.
P a g e |7
IB Chemistry - Topic 10 and 20 Guide
Topic 20 (HL):
Introduction
Examples of how to name non-cyclic organic compounds from structural drawings and vice-versa, with
chains of up to 6 carbon atoms with one of the following functional groups: amine, amide, ester and nitrile.
Nucleophillic Substitution Reactions
Explanation of why the hydroxide ion is a better nucleophile than water.
Examples of mechanisms of nucleophillic substitution by OH-, CN-, and NH3 on haloalkanes.
Explanation of reasons why haloalkanes show this mechanism of reaction and factors which can affect the
rates.
Examples of the reduction of nitriles using hydrogen and a nickel catalyst.
Elimination Reactions
Definition of: elimination.
Examples of mechanisms of elimination reactions by OH- on haloalkanes and the conditions employed to
favour elimination over substitution.
Condensation Reactions
Examples of the formation and hydrolysis of esters and polyesters including reagents used.
Examples of naturally occurring esters, of the application of esters in biofuels, polysters and in other
common applications.
Examples of the formation of amides including reagents used.
Reaction Pathways
Tables and/or flow charts summarising all the reactions (including reagents) on organic compounds
which you have met, as summarised in the scheme below.
Note: There are occasions where this duplicates parts of the organic notes above. In that case, the reactions will be
most useful for helping to answer questions if they appear in this section and a reference appears in the section above
rather than the other way around.
Examples of two step reaction pathways with reagents, conditions and equations e.g. the conversion of 1bromopropane to 1-butylamine can be done in two stages: 1-bromopropane can be reacted with potassium
cyanide to form propanenitrile, which can then be reduced by heating with hydrogen and a nickel catalyst.
P a g e |8
IB Chemistry - Topic 10 and 20 Guide
Stereoisomerism
Definition of: stereoisomer, geometrical isomerism and optical isomerism, asymmetric, chiral, enantiomer,
racemate/racemic mixture, plane-polarised.
Examples of isomerism shown by non-cyclic alkenes, how to name isomers and explanation of why
alkenes show stereoisomerism.
Examples of isomerism shown by cyclic alkanes of 3 and 4 carbon atoms.
Explain the difference in the physical and chemical properties of geometrical isomers and enantiomers,
with examples.
Example and explanations of how racemates are formed
Describe the use of a polarimeter in distinguishing between optical isomers.
P a g e |9
IB Chemistry - Topic 10 and 20 Guide
Topic 10 SL Past exam paper questions:
1.
Which of the following statements about alkenes is not correct?
A.
They have reactive double bonds.
B.
They can form addition polymers.
C.
They react mainly by substitution.
D.
They can react with water to form alcohols.
(Total 1 mark)
2.
What is the type of mechanism and an important feature of the reaction between C(CH3)3Br and
aqueous NaOH?
Mechanism
Feature
A.
SN1
a transition state
B.
SN1
an intermediate
C.
SN2
a transition state
D.
SN2
an intermediate
(Total 1 mark)
3.
Which of the following are isomers of pentane?
I.
2-methylpentane
II.
methylbutane
III.
dimethylpropane
A.
I and II only
B.
I and III only
C.
II and III only
D.
I, II and III
(Total 1 mark)
P a g e | 10
IB Chemistry - Topic 10 and 20 Guide
4.
Which of the following pairs are members of the same homologous series?
A.
CH3CH2CH2OH and CH3CH2CHO
B.
CH3CH(OH)CH3 and CH3CH2CH(OH)CH3
C.
CH3COCH3 and CH3CH2COOH
D.
CH3COCH2CH3 and CH3CH2CHO
(Total 1 mark)
5.
Alkenes are important starting materials for a variety of products.
(a)
State and explain the trend of the boiling points of the first five members of the alkene
homologous series.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(3)
(b)
Describe two features of a homologous series.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
(Total 5 marks)
P a g e | 11
IB Chemistry - Topic 10 and 20 Guide
6.
Below is a schematic diagram representing some reactions of ethene. The letters A–D represent
the organic compounds formed from the reactants and catalysts shown.
Deduce the structural formulas of compounds A, B, C, and D and state the IUPAC name of
compound C.
P a g e | 12
IB Chemistry - Topic 10 and 20 Guide
A:
B:
C:
IUPAC name: ..............................................................................................................
D:
(Total 5 marks)
7.
Describe a chemical test that could be used to distinguish between pent-1-ene and pentane.
................................................................................................................................................
................................................................................................................................................
................................................................................................................................................
................................................................................................................................................
(Total 2 marks)
P a g e | 13
IB Chemistry - Topic 10 and 20 Guide
8.
State and explain whether the following molecules are primary, secondary or tertiary
halogenoalkanes.
E:
................................................................................................................................................
................................................................................................................................................
F:
................................................................................................................................................
................................................................................................................................................
G:
................................................................................................................................................
................................................................................................................................................
(Total 4 marks)
P a g e | 14
IB Chemistry - Topic 10 and 20 Guide
9.
Explain, using equations, the following steps in the free-radical mechanism of the reaction of
methane with chlorine.
•
•
•
Initiation
Propagation
Termination
................................................................................................................................................
................................................................................................................................................
................................................................................................................................................
................................................................................................................................................
................................................................................................................................................
................................................................................................................................................
................................................................................................................................................
................................................................................................................................................
(Total 4 marks)
P a g e | 15
IB Chemistry - Topic 10 and 20 Guide
10.
Two compounds, A and D, each have the formula C4H9Cl.
Compound A is reacted with dilute aqueous sodium hydroxide to produce compound B with a
formula of C4H10O. Compound B is then oxidized with acidified potassium manganate(VII) to
produce compound C with a formula of C4H8O. Compound C resists further oxidation by
acidified potassium manganate(VII).
Compound D is reacted with dilute aqueous sodium hydroxide to produce compound E with a
formula of C4H10O. Compound E does not react with acidified potassium manganate(VII).
Deduce the structural formulas for compounds A, B, C, D and E.
A:
B:
C:
D:
E:
(Total 5 marks)
P a g e | 16
IB Chemistry - Topic 10 and 20 Guide
11.
2-chloro-3-methylbutane reacts with sodium hydroxide via an SN2 mechanism.
Explain the mechanism by using curly arrows to represent the movement of electron pairs.
(Total 4 marks)
12.
Which organic molecule is not a structural isomer of pentan-1-ol?
A.
pentan-2-ol
B.
2-methylpentan-2-ol
C.
2-methylbutan-2-ol
D.
pentan-3-ol
(Total 1 mark)
13.
Which of the structures below is an aldehyde?
A.
CH3CH2CH2CH2OH
B.
CH3CH2COCH3
C.
CH3CH2COOCH3
D.
CH3CH2CH2CHO
(Total 1 mark)
P a g e | 17
IB Chemistry - Topic 10 and 20 Guide
14.
What product is formed when CH3CH(OH)CH3 is reacted with acidified potassium
dichromate(VI)?
A.
CH3COOCH3
B.
CH3CH2CHO
C.
CH3CH2COOH
D.
CH3COCH3
(Total 1 mark)
15.
Which type of reaction occurs when 2-iodo-2-methylpropane, C(CH3)3I, reacts with aqueous
sodium hydroxide, NaOH(aq)?
A.
Addition
B.
Free-radical substitution
C.
SN1
D.
SN2
(Total 1 mark)
16.
(i)
Describe a chemical test that could be used to distinguish between propane and propene.
In each case state the result of the test.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
P a g e | 18
IB Chemistry - Topic 10 and 20 Guide
(ii)
Under certain conditions propene can polymerize to form poly(propene). State the type of
polymerization taking place and draw a section of the polymer to represent the repeating
unit.
......................................................................................................................................
......................................................................................................................................
(2)
(iii) Other than polymerization, state one reaction of alkenes which is of economic importance.
......................................................................................................................................
......................................................................................................................................
(1)
(Total 5 marks)
17.
Propan-1-ol and propan-2-ol are two structural isomers of C3H8O.
(i)
State the equation for the complete combustion of C3H8O.
......................................................................................................................................
......................................................................................................................................
(2)
(ii)
Both propan-1-ol and propan-2-ol can be oxidized in aqueous solution by potassium
dichromate(VI). State any necessary conditions for the oxidation to occur and describe
the colour change during the oxidation process.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(3)
P a g e | 19
IB Chemistry - Topic 10 and 20 Guide
(iii)
State the name(s) and structure(s) of the organic product(s) that can be formed when each
of the alcohols is oxidized and suggest why one of the alcohols gives two organic
products and the other only gives one organic product.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(5)
(Total 10 marks)
18.
Halogenoalkanes can undergo SN1 and SN2 reactions with aqueous sodium hydroxide.
Which halogenoalkane will react fastest with a 0.1 mol dm–3 solution of aqueous sodium
hydroxide?
A.
2-chloro-2-methylpropane
B.
2-iodo-2-methylpropane
C.
1-chlorobutane
D.
1-iodobutane
(Total 1 mark)
P a g e | 20
IB Chemistry - Topic 10 and 20 Guide
19.
There are several structural isomers with the molecular formula C5H11Br.
(a)
Deduce the name of one of the isomers which can exist as enantiomers and draw threedimensional representations of its two enantiomers.
......................................................................................................................................
(3)
(b)
All the isomers react when warmed with a dilute aqueous solution of sodium hydroxide
according to the equation below.
C5H11Br + NaOH → C5H11OH + NaBr
(i)
The reaction with 1-bromopentane proceeds by an SN2 mechanism. Describe this
mechanism using structural formulas and curly arrows to represent the movement
of electron pairs.
(3)
P a g e | 21
IB Chemistry - Topic 10 and 20 Guide
(ii)
The reaction with 2-bromo-2-methylbutane proceeds by an SN1 mechanism.
Describe this mechanism using structural formulas and curly arrows to represent
the movement of electron pairs.
(3)
(iii)
Explain why 1-bromopentane reacts by an SN2 mechanism whereas 2-bromo-2methylbutane reacts by an SN1 mechanism.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(3)
(iv)
Explain whether the boiling point of 1-bromopentane will be higher, lower or the
same as that of 2-bromo-2-methylbutane.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(3)
P a g e | 22
IB Chemistry - Topic 10 and 20 Guide
(v)
The product C5H11OH formed from the reaction with 1-bromopentane is warmed
with ethanoic acid in the presence of a few drops of concentrated sulfuric acid.
State the name of the type of reaction taking place and the structural formula of the
organic product.
...........................................................................................................................
...........................................................................................................................
(2)
(c)
If the conditions of the reaction in (b) are changed so that a hot solution of sodium
hydroxide in ethanol is used then a different reaction occurs. The reaction with 2-bromo2-methylbutane gives two different organic products. State the type of reaction taking
place and suggest the identity (name or structure) of these two products.
Explain whether or not they can exist as geometrical isomers.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(4)
(Total 21 marks)
20.
Which is the best definition of structural isomers?
A.
Compounds which have atoms with the same atomic numbers but different mass numbers
B.
Compounds which have the same general formula but differ by a CH2 group
C.
Compounds which have the same empirical formula but different molecular formulas
D.
Compounds which have the same molecular formula but different arrangements of atoms
(Total 1 mark)
P a g e | 23
IB Chemistry - Topic 10 and 20 Guide
21.
Which is the correct classification of these alcohols?
1
2
1
2
3
3
A.
tertiary
secondary
primary
B.
tertiary
primary
secondary
C.
tertiary
tertiary
secondary
D.
secondary
primary
secondary
(Total 1 mark)
22.
Which substances are possible products of the incomplete combustion of octane?
A.
Carbon dioxide and hydrogen gas
B.
Carbon monoxide and water vapour
C.
Carbon monoxide and hydrogen gas
D.
Methane and hydrogen gas
(Total 1 mark)
P a g e | 24
IB Chemistry - Topic 10 and 20 Guide
23.
Which structure could represent a repeating unit of a polymer formed from propene?
A.
( CH2–CH(CH3) )
B.
( CH2–CH2–CH2 )
C.
( CH(CH3)–CH(CH3) )
D.
( CH2–CH2 )
(Total 1 mark)
24.
Chloroethene, C2H3Cl, is an important organic compound used to manufacture the polymer
poly(chloroethene).
(i)
Draw the Lewis structure for chloroethene and predict the H – C– Cl bond angle.
......................................................................................................................................
(2)
(ii)
Draw a section of poly(chloroethene) containing six carbon atoms.
(1)
P a g e | 25
IB Chemistry - Topic 10 and 20 Guide
(iii)
Outline why the polymerization of alkenes is of economic importance and why the
disposal of plastics is a problem.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
(Total 5 marks)
25.
(i)
Chloroethene can be converted to ethanol in two steps. For each step deduce an overall
equation for the reaction taking place.
Step 1:
......................................................................................................................................
......................................................................................................................................
Step 2:
......................................................................................................................................
......................................................................................................................................
(2)
(ii)
State the reagents and conditions necessary to prepare ethanoic acid from ethanol in the
laboratory.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
P a g e | 26
IB Chemistry - Topic 10 and 20 Guide
(iii)
State an equation, including state symbols, for the reaction of ethanoic acid with water.
Identify a Brønsted-Lowry acid in the equation and its conjugate base.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(3)
(Total 7 marks)
26.
Ethanol is part of the homologous series of alcohols. Describe two features of a homologous
series.
(Total 2 marks)
P a g e | 27
IB Chemistry - Topic 10 and 20 Guide
27.
(a)
(i)
Below are four structural isomers of alcohols with molecular formula C4H10O.
State the name of each of the isomers A, B, C and D.
(4)
(ii)
Determine the isomer that cannot be oxidized by acidified potassium
dichromate(VI), K2Cr2O7.
(1)
(iii)
Determine the isomer which can be oxidized to butanal.
(1)
(iv)
Determine the isomer which can be oxidized to butanone.
(1)
(v)
Suggest the structural formula of another isomer of C4H10O.
(1)
(b)
P a g e | 28
(i)
Isomer A is formed by reacting 1-bromobutane with aqueous sodium hydroxide.
IB Chemistry - Topic 10 and 20 Guide
State whether the reaction would proceed via an SN1 or SN2 mechanism.
(1)
(ii)
Explain the mechanism named in part (b) (i) using curly arrows to represent the
movement of electron pairs.
(3)
(Total 12 marks)
28.
Outline the different mechanisms involved in the manufacture of low-density poly(ethene) and
high-density poly(ethene).
................................................................................................................................................
................................................................................................................................................
................................................................................................................................................
................................................................................................................................................
(Total 2 marks)
29.
What is the structural formula of 2,3-dibromo-3-methylhexane?
A.
CH3CHBrCHBrCH(CH3)CH2CH3
B.
CH3CHBrCBr(CH3)CH2CH2CH3
C.
CH3CH2CHBrCBr(CH2CH3)2
D.
CH3CHBrCHBrCH(CH2CH3)2
(Total 1 mark)
P a g e | 29
IB Chemistry - Topic 10 and 20 Guide
30.
What happens when a few drops of bromine water are added to excess hex-1-ene and the
mixture is shaken?
I.
The colour of the bromine water disappears.
II.
The organic product formed does not contain any carbon-carbon double bonds.
III.
2-bromohexane is formed.
A.
I and II only
B.
I and III only
C.
II and III only
D.
I, II and III
(Total 1 mark)
31.
What is the product of the following reaction?
2

Cr2 O 7 /H
CH3CH(OH)CH3 


A.
CH3COOH
B.
CH3COCH3
C.
CH3CH2COOH
D.
CH3CH2CH3
(Total 1 mark)
P a g e | 30
IB Chemistry - Topic 10 and 20 Guide
(iii)
State an equation, including state symbols, for the reaction of ethanoic acid with water. Identify
a Brønsted-Lowry acid in the equation and its conjugate base.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(3)
(Total 7 marks)
32.
Alkenes are an economically and chemically important family of organic compounds.
(i)
The reaction of alkenes with bromine water provides a test for unsaturation in the
laboratory. Describe the colour change when bromine water is added to chloroethene.
(1)
(ii)
Deduce the Lewis structure of chloroethene and identify the formula of the repeating unit
of the polymer poly(chloroethene).
(2)
(iii)
Besides polymerization, state two commercial uses of the reactions of alkenes.
(2)
(Total 5 marks)
P a g e | 31
IB Chemistry - Topic 10 and 20 Guide
A.
CH3COOH
B.
CH3COCH3
C.
CH3CH2COOH
D.
CH3CH2CH3
(Total 1 mark)
tx1ÈŽ?ÈŽ?(iii)
State an equation, including state symbols, for the reaction of ethanoic acid with
water. Identify a Brønsted-Lowry acid in the equation and its conjugate base.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(3)
(Total 7 marks)
33.
But-2-ene can be converted to butan-2-one in two stages.
(i)
Draw the structural formulas of but-2-ene and butan-2-one.
(2)
(ii)
Deduce a reaction pathway for the two stages of the reaction. Your answer should include
the fully balanced equation for each stage of the reaction and the reagents and conditions
for the two stages.
(5)
(Total 7 marks)
P a g e | 32
IB Chemistry - Topic 10 and 20 Guide
(2)
(Total 5 marks)
00äú?äú?
22253797374656d0093a515669300000a0021008a01000000000000000028fc1300040000002d0100
0004000000f0010100030000000000
A.
CH3COOH
B.
CH3COCH3
C.
CH3CH2COOH
D.
CH3CH2CH3
(Total 1 mark)
tx1ÈŽ?ÈŽ?(iii)
State an equation, including state symbols, for the reaction of ethanoic acid with
water. Identify a Brønsted-Lowry acid in the equation and its conjugate base.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(3)
(Total 7 marks)
34.
(i)
Deduce the structural formulas of the two alcohol isomers of molecular formula C3H8O.
Name each isomer and identify each as either a primary or a secondary alcohol.
(3)
(ii)
P a g e | 33
Oxidation of the alcohol isomers lead to the formation of different organic products.
Determine the structures of the organic products formed from the oxidation of each
IB Chemistry - Topic 10 and 20 Guide
alcohol isomer in (i) above and list the conditions required to obtain the different products.
(5)
(Total 8 marks)
aiHÓß HÓß mmercial uses of the reactions of alkenes.
(2)
(Total 5 marks)
00äú?äú?
22253797374656d0093a515669300000a0021008a01000000000000000028fc1300040000002d0100
0004000000f0010100030000000000
A.
CH3COOH
B.
CH3COCH3
C.
CH3CH2COOH
D.
CH3CH2CH3
(Total 1 mark)
P a g e | 34
IB Chemistry - Topic 10 and 20 Guide
tx1ÈŽ?ÈŽ?(iii)
State an equation, including state symbols, for the reaction of ethanoic acid with
water. Identify a Brønsted-Lowry acid in the equation and its conjugate base.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(3)
(Total 7 marks)
35.
What organic product is formed in the following reaction?
H SO 4

(CH3CH2)CH=CH(CH2CH3) + H2O 2 
A.
CH3(CH2)2CH(OH)CH2CH3
B.
CH3(CH2)5CH3
C.
CH3(CH2)2CH(OSO3H)CH2CH3
D.
CH3(CH2)6OH
(Total 1 mark)
P a g e | 35
IB Chemistry - Topic 10 and 20 Guide
36.
Which of the following substances are structural isomers of each other?
I.
CH3(CH2)3CH3
II.
(CH3)2CHCH3
III.
CH3CH(CH3)CH2CH3
A.
I and II only
B.
I and III only
C.
II and III only
D.
I, II and III
(Total 1 mark)
37.
Which order is correct when the following substances are arranged in order of increasing
boiling point?
A.
CH3CH3 < CH3CHO < CH3CH2OH
B.
CH3CHO < CH3CH2OH < CH3CH3
C.
CH3CH2OH < CH3CH3 < CH3CHO
D.
CH3CH3 < CH3CH2OH < CH3CHO
(Total 1 mark)
P a g e | 36
IB Chemistry - Topic 10 and 20 Guide
38.
Which monomer could be used to form a polymer with the following repeating unit?
A.
CH3CH2Cl
B.
CH2ClCH2Cl
C.
CH2CHCl
D.
CHClCHCl
(Total 1 mark)
39.
Which reaction pathway describes how ethanol can be formed?
A.
addition
elimination
 chloroethane 
  ethanol
ethene  
B.
substitution
nucleophilic substitution
 chloroethane 

 ethanol
ethane   
C.
substitution
 ethanol
ethene   
D.
addition
 ethanol
ethane  
(Total 1 mark)
P a g e | 37
IB Chemistry - Topic 10 and 20 Guide
40.
The alkenes are an example of a homologous series.
(a)
State the name of the alkene shown.
......................................................................................................................................
(1)
(b)
Bromine water, Br2(aq), can be used to distinguish between the alkanes and the alkenes.
(i)
Describe the colour change observed when the alkene shown in part (a) is added to
bromine water.
...........................................................................................................................
...........................................................................................................................
(1)
(ii)
Draw the structural formula and state the name of the product formed.
...........................................................................................................................
(2)
(Total 4 marks)
P a g e | 38
IB Chemistry - Topic 10 and 20 Guide
41.
The polymerization of the alkenes is one of the most significant reactions of the twentieth
century.
(i)
Outline two reasons why the polymers of the alkenes are of economic importance.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
(ii)
State the type of polymerization reaction shown by the alkene below.
......................................................................................................................................
......................................................................................................................................
(1)
(iii)
Deduce the structure of the resulting polymer showing three repeating units.
(1)
P a g e | 39
IB Chemistry - Topic 10 and 20 Guide
(iv)
Explain why monomers are often gases or volatile liquids, but polymers are solids.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
(Total 6 marks)
42.
State the name of the product and identify the type of reaction which occurs between ethene and
hydrogen chloride.
(Total 2 marks)
43.
Consider the following sequence of reactions.
reaction1
reaction2
reaction3
RCH3   RCH2Br   RCH2OH   RCOOH
RCH3 is an unknown alkane in which R represents an alkyl group.
(a)
The alkane contains 81.7 % by mass of carbon. Determine its empirical formula, showing
your working.
(3)
(b)
Equal volumes of carbon dioxide and the unknown alkane are found to have the same
mass, measured to an accuracy of two significant figures, at the same temperature and
pressure. Deduce the molecular formula of the alkane.
(1)
(c)
(i)
State the reagent and conditions needed for reaction 1.
(2)
(ii)
State the reagent(s) and conditions needed for reaction 3.
(2)
P a g e | 40
IB Chemistry - Topic 10 and 20 Guide
(d)
Reaction 1 involves a free-radical mechanism. Describe the stepwise mechanism, by
giving equations to represent the initiation, propagation and termination steps.
(4)
(e)
The mechanism in reaction 2 is described as SN2.
(i)
State the meaning of each of the symbols in SN2.
(1)
(ii)
Explain the mechanism of this reaction using curly arrows to show the movement
of electron pairs, and draw the structure of the transition state.
(3)
(Total 16 marks)
44.
Propan-1-ol has two structural isomers.
(i)
Deduce the structural formula of each isomer.
(2)
(ii)
Identify the isomer from part (i) which has the higher boiling point and explain your
choice. Refer to both isomers in your explanation.
(2)
(Total 4 marks)
45.
Which three compounds can be considered to be a homologous series?
A.
CH3OH,
CH3CH2OH,
CH3CH2CH2OH
B.
CH3CH2OH,
C.
CH3CH2CH(OH)CH3,
CH3CH2CH2CH2OH,
D.
CH3CH2CH2CH2OH,
CH3CH2OCH2CH3,
CH3CHO,
CH3COOH
(CH3)3COH
(CH3)2CH2CHO
(Total 1 mark)
P a g e | 41
IB Chemistry - Topic 10 and 20 Guide
46.
What is the IUPAC name for CH3CH2CH(CH3)CH3?
A.
1,1-dimethylpropane
B.
2-ethylpropane
C.
2-methylbutane
D.
3-methylbutane
(Total 1 mark)
3CH2CH2CH2OH,
D.
(CH3)3COH
CH3CH2CH2CH2OH,
CH3CH2OCH2CH3,
(CH3)2CH2CHO
(Total 1 mark)
47.
When bromine water is shaken with a liquid organic compound, it is rapidly decolorized. What
can be determined from this test?
A.
The compound is an alcohol.
B.
The compound is an alkane.
C.
The compound is an alkene.
D.
The compound is an iodoalkane.
(Total 1 mark)
P a g e | 42
IB Chemistry - Topic 10 and 20 Guide
48.
Which conditions are required to obtain a good yield of a carboxylic acid when ethanol is
oxidized using potassium dichromate(VI), K2Cr2O7(aq)?
I.
Add sulfuric acid
II.
Heat the reaction mixture under reflux
III.
Distil the product as the oxidizing agent is added
A.
I and II only
B.
I and III only
C.
II and III only
D.
I, II and III
(Total 1 mark)
2OH,
CH3CH2OCH2CH3,
(CH3)2CH2CHO
(Total 1 mark)
49.
Three compounds with similar relative molecular masses are butane, propanal and propan-1-ol.
(i)
List the three compounds in order of increasing boiling point (lowest first) and explain
the differences in their boiling points.
(4)
(ii)
Predict, with an explanation, which of the three compounds is least soluble or miscible in
water.
(2)
(iii)
When propan-1-ol is oxidized using a warm acidified solution of potassium
dichromate(VI) two different organic products can be obtained. Deduce the name and
structural formula for each of these two products.
(3)
(iv)
Propan-2-ol is an isomer of propan-1-ol. Draw the structure of propan-2-ol.
(1)
(v)
P a g e | 43
Identify the class of alcohols that propan-2-ol belongs to and state the name of the organic
product formed when it is oxidized by an acidified solution of potassium dichromate(VI).
IB Chemistry - Topic 10 and 20 Guide
(2)
(Total 12 marks)
50.
Ethanol can be formed from ethene in a two step reaction:
(i)
State the name of the reagent used for step 1.
(1)
(ii)
State the name of the reagent and the conditions used for step 2.
(2)
(iii)
The mechanism involved in step 2 is SN2. Explain how the reaction proceeds using curly
arrows to represent the movement of electron pairs.
(3)
(iv)
Outline how ethanol is manufactured from ethene in industry and state one important
commercial use of ethanol.
(2)
(Total 8 marks)
P a g e | 44
IB Chemistry - Topic 10 and 20 Guide
51.
What is the product of the oxidation of butan-2-ol?
A.
But-2-ene
B.
Butanoic acid
C.
Butanal
D.
Butanone
(Total 1 mark)
52.
Which is a tertiary halogenoalkane?
A.
CH3CH2CH2Br
B.
CH3CH2CH(CH3)Cl
C.
C(CH3)3Br
D.
CH3CHClCH2CH3
(Total 1 mark)
P a g e | 45
IB Chemistry - Topic 10 and 20 Guide
53.
What is the IUPAC name of the following compound?
A.
2-methylbutane
B.
Ethylpropane
C.
3-methylbutane
D.
Pentane
(Total 1 mark)
54.
Which equations represent the incomplete combustion of methane?
I.
CH4(g) + 2O2(g) → CO2(g) + 2H2
II.
CH4(g) + 1½O2(g) → CO(g) + 2H2O(g)
III.
CH4(g) + O2(g) → C(s) + 2H2O(g)
A.
I and II only
B.
I and III only
C.
II and III only
D.
I, II and III
(Total 1 mark)
P a g e | 46
IB Chemistry - Topic 10 and 20 Guide
55.
In some countries, ethanol is mixed with gasoline (petrol) to produce a fuel for cars called
gasohol.
(i)
Define the term average bond enthalpy.
(2)
(ii)
Use the information from Table 10 of the Data Booklet to determine the standard
enthalpy change for the complete combustion of ethanol.
CH3CH2OH(g) + 3O2(g) → 2CO2(g) + 3H2O(g)
(3)
(iii)
The standard enthalpy change for the complete combustion of octane, C8H18, is
–5471 kJ mol–1. Calculate the amount of energy produced in kJ when 1 g of ethanol and
1 g of octane is burned completely in air.
(2)
(iv)
Ethanol can be oxidized using acidified potassium dichromate, K2Cr2O7, to form two
different organic products.
CH3CH2OH
A
B
State the structural formulas of the organic products A and B and describe the conditions
required to obtain a high yield of each of them.
(4)
(v)
Deduce and explain whether ethanol or A has the higher boiling point.
(2)
(vi)
Ethene can be converted into ethanol by direct hydration in the presence of a catalyst
according to the following equation.
C2H4(g) + H2O(g)
CH3CH2OH(g)
For this reaction identify the catalyst used and state one use of the ethanol formed other
than as a fuel.
(2)
(Total 15 marks)
P a g e | 47
IB Chemistry - Topic 10 and 20 Guide
56.
(i)
State the name of one structural isomer of pentane.
(1)
(ii)
Sodium hydroxide reacts with 1-bromopentane via an SN2 mechanism.
Describe the mechanism of this reaction using curly arrows to represent the movement of
electron pairs.
(4)
(Total 5 marks)
57.
What structural feature must a molecule have in order to undergo addition polymerization?
A.
Two functional groups
B.
A carbon–carbon double bond
C.
Carbon atoms singly bonded together
D.
A polar covalent bond
(Total 1 mark)
58.
Ethanol can be oxidized using acidified potassium dichromate, K2Cr2O7, to form two different
organic products.
CH3CH2OH
A
B
State the structural formulas of the organic products A and B and describe the conditions
required to obtain a high yield of each of them.
(Total 4 marks)
59.
Ethene can be converted into ethanol by direct hydration in the presence of a catalyst according
to the following equation.
C2H4(g) + H2O(g)
CH3CH2OH(g)
For this reaction, identify the catalyst used and state one use of the ethanol formed other than as
a fuel.
(Total 2 marks)
P a g e | 48
IB Chemistry - Topic 10 and 20 Guide
60.
How many structural isomers exist with the formula C3H5Cl3?
A.
3
B.
4
C.
5
D.
6
(Total 1 mark)
61.
Which substance is produced by the reaction of hydrogen with a vegetable oil?
A.
Margarine
B.
Nylon
C.
Polypropene
D.
Soap
(Total 1 mark)
62.
Which substance is not produced during the combustion of alkanes?
A.
CO2
B.
CO
C.
C
D.
H2
(Total 1 mark)
P a g e | 49
IB Chemistry - Topic 10 and 20 Guide
63.
Propene is converted to propanone in a two stage process.
Propene → X → Propanone
What is the formula of compound X?
A.
CH3CHBrCH3
B.
CH3CH2CH2Br
C.
CH3CHOHCH3
D.
CH3CH2CH2OH
(Total 1 mark)
64.
(a)
The boiling points of the isomers of pentane, C5H12, shown are 10, 28 and 36 °C, but not
necessarily in that order.
(i)
Identify the boiling points for each of the isomers A, B and C and state a reason for
your answer.
Isomer
A
B
C
Boiling point
...........................................................................................................................
...........................................................................................................................
(3)
P a g e | 50
IB Chemistry - Topic 10 and 20 Guide
(ii)
State the IUPAC names of isomers B and C.
B: .......................................................................................................................
C: .......................................................................................................................
(2)
(b)
Both C5H12 and C5H11OH can be used as fuels. Predict which compound would release a
greater amount of heat per gram when it undergoes complete combustion. Suggest two
reasons to support your prediction.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(3)
(Total 8 marks)
65.
Halogenoalkanes can undergo substitution reactions with potassium hydroxide solution.
(i)
State an equation for the reaction of C4H9Cl with KOH.
(1)
(ii)
Substitution reactions may occur by either of two mechanisms namely SN1 or SN2.
Outline the meaning of the term SN1.
(2)
(iii)
Predict the mechanism (SN1 or SN2) expected for the reaction of the following
halogenoalkanes with aqueous KOH.
1-chlorobutane to form butan-1-ol
2-chloro-2-methylpropane to form 2 methylpropan-2-ol.
(2)
P a g e | 51
IB Chemistry - Topic 10 and 20 Guide
(iv)
Explain the mechanism of each reaction in part (iii) using curly arrows to represent the
movement of electron pairs.
(6)
(Total 11 marks)
66.
(i)
Draw four structural isomers of molecular formula C4H10O which contain the –OH group.
(4)
(ii)
On reaction with acidified potassium dichromate(VII), two of the isomers are oxidized in
two steps to produce different products. Draw the structural formula of the two products
formed from one of the isomers.
(2)
(iii)
A third isomer is oxidized in one step. Draw the structural formula of the organic product
formed.
(1)
(iv)
State the colour change that takes place in these oxidation reactions.
(1)
(v)
Identify the isomer which resists oxidation by acidified potassium dichromate(VI).
(1)
(Total 9 marks)
67.
Which statement about successive members of all homologous series is correct?
A.
They have the same empirical formula.
B.
They differ by a CH2 group.
C.
They have the same physical properties.
D.
They differ in their degree of unsaturation.
(Total 1 mark)
68.
The following is a three-dimensional representation of an organic molecule.
P a g e | 52
IB Chemistry - Topic 10 and 20 Guide
Which statement is correct?
A.
The correct IUPAC name of the molecule is 2-methylpentane.
B.
All the bond angles will be approximately 90°.
C.
One isomer of this molecule is pentane.
D.
The boiling point of this compound would be higher than that of pentane.
(Total 1 mark)
P a g e | 53
IB Chemistry - Topic 10 and 20 Guide
69.
Which compound forms when hydrogen bromide is added to but-2-ene?
A.
2-bromobutane
B.
2,3-dibromobutane
C.
1-bromobutane
D.
1,2-dibromobutane
(Total 1 mark)
70.
Which products can be potentially obtained from crude oil and are economically important?
I.
II.
III.
Plastics
Margarine
Motor fuel
A.
I and II only
B.
I and III only
C.
II and III only
D.
I, II and III
(Total 1 mark)
71.
Propane, C3H8, undergoes incomplete combustion in a limited amount of air. Which products
are most likely to be formed during this reaction?
A.
Carbon monoxide and water
B.
Carbon monoxide and hydrogen
C.
Carbon dioxide and hydrogen
D.
Carbon dioxide and water
(Total 1 mark)
P a g e | 54
IB Chemistry - Topic 10 and 20 Guide
72.
(a)
List two characteristics of a homologous series.
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
(1)
(b)
Ethanol and ethanoic acid can be distinguished by their melting points. State and explain
which of the two compounds will have a higher melting point.
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
(2)
(c)
Draw the three isomers containing the alcohol functional group of formula C4H9OH.
(2)
(Total 5 marks)
P a g e | 55
IB Chemistry - Topic 10 and 20 Guide
73.
The following is a computer-generated representation of the molecule, methyl 2hydroxy benzoate, better known as oil of wintergreen.
(i)
Deduce the empirical formula of methyl 2-hydroxy benzoate and draw the full structural
formula, including any multiple bonds that may be present.
The computer-generated representation shown does not distinguish between single and
multiple bonds.
(2)
(ii)
In this representation, two of the carbon-oxygen bond lengths shown are 0.1424 nm and
0.1373 nm. Explain why these are different and predict the carbon-oxygen bond length in
carbon dioxide.
(2)
(iii)
Name all the functional groups present in the molecule.
(2)
(Total 6 marks)
P a g e | 56
IB Chemistry - Topic 10 and 20 Guide
74.
(i)
State and explain the trend in the boiling points of the first six alkanes involving straightchains.
(2)
(ii)
Write an equation for the reaction between methane and chlorine to form chloromethane.
Explain this reaction in terms of a free-radical mechanism.
(5)
(Total 7 marks)
75.
(i)
Identify the formulas of the organic products, A–E, formed in the reactions, I–IV:


I.
H
H
 A 
 B
CH3(CH2)8OH + K2Cr2O7 
II.
(CH3)3CBr + NaOH  C
III.
H
 D
(CH3)2CHOH + K2Cr2O7 
IV.
H2C=CH2 + Br2  E

(5)
(ii)
H2C=CH2 can react to form a polymer. Name this type of polymer and draw the
structural formula of a section of this polymer consisting of three repeating units.
(2)
(Total 7 marks)
P a g e | 57
IB Chemistry - Topic 10 and 20 Guide
Topic 10 HL Past exam paper questions:
1.
Which molecule has a chiral centre?
A.
CH3CH=CHCHO
B.
(CH3)2C=CHCH2OH
C.
CH3OCH2CH3
D.
CH3CHOHCH2CH3
(Total 1 mark)
2.
The compounds H2NCH2CH2NH2 and HOOCCH2COOH react to form a polymer. What is the
structure of the repeating unit of the polymer?
A.
( HNCH2CONHCH2CH2NHCO )
B.
( HNCH2CH2NHCOCH2CO )
C.
( OCCH2CONHCH2NHCO )
D.
( HNCH2CH2NHCOCH2NH )
(Total 1 mark)
P a g e | 58
IB Chemistry - Topic 10 and 20 Guide
3.
Which two molecules are cis-trans isomers of each other?
A.
X and Z
B.
X and Y
C.
W and Y
D.
W and Z
(Total 1 mark)
4.
What is the correct order of reaction types in the following sequence?
I C H OH 
II C H COOH 
III
 C2H5COOC2H5
C3H7Br 
3 7
2 5
I
II
III
A.
substitution
oxidation
condensation
B.
addition
substitution
condensation
C.
oxidation
substitution
condensation
D.
substitution
oxidation
substitution
(Total 1 mark)
P a g e | 59
IB Chemistry - Topic 10 and 20 Guide
5.
Deduce an equation for the reaction between propanoic acid and methanol. Identify the catalyst
and state the name of the organic compound, X, formed.
................................................................................................................................................
................................................................................................................................................
................................................................................................................................................
................................................................................................................................................
................................................................................................................................................
................................................................................................................................................
................................................................................................................................................
................................................................................................................................................
(Total 4 marks)
6.
2-chloro-3-methylbutane reacts with sodium hydroxide via an SN2 mechanism.
Explain the mechanism by using curly arrows to represent the movement of electron pairs.
(Total 4 marks)
P a g e | 60
IB Chemistry - Topic 10 and 20 Guide
7.
1-chlorobutane can be converted to a pentylamine via a two stage process.
Deduce equations for each step of this conversion including any catalyst required and name the
organic product produced at each stage.
................................................................................................................................................
................................................................................................................................................
................................................................................................................................................
................................................................................................................................................
................................................................................................................................................
................................................................................................................................................
................................................................................................................................................
................................................................................................................................................
................................................................................................................................................
................................................................................................................................................
................................................................................................................................................
................................................................................................................................................
(Total 5 marks)
8.
Propanitrile can be prepared by reacting bromoethane with potassium cyanide. Which statement
is not correct about the reaction between bromoethane and potassium cyanide?
A.
The reaction is bi-molecular.
B.
The reaction follows the SN2 mechanism.
C.
Homolytic fission occurs between the carbon-bromine bond in bromoethane.
D.
The cyanide ion, :CN–, acts as a nucleophile.
(Total 1 mark)
P a g e | 61
IB Chemistry - Topic 10 and 20 Guide
9.
Which reactants could be used to form the compound below?
A.
Butanoic acid and ethanol
B.
Propanoic acid and ethanol
C.
Ethanoic acid and propan-1-ol
D.
Ethanoic acid and butan-1-ol
(Total 1 mark)
P a g e | 62
IB Chemistry - Topic 10 and 20 Guide
10.
Which compound is optically active?
(Total 1 mark)
11.
There are several structural isomers with the molecular formula C5H11Br.
(a)
Deduce the name of one of the isomers which can exist as enantiomers and draw threedimensional representations of its two enantiomers.
......................................................................................................................................
(3)
P a g e | 63
IB Chemistry - Topic 10 and 20 Guide
(b)
All the isomers react when warmed with a dilute aqueous solution of sodium hydroxide
according to the equation below.
C5H11Br + NaOH → C5H11OH + NaBr
(i)
The reaction with 1-bromopentane proceeds by an SN2 mechanism. Describe this
mechanism using structural formulas and curly arrows to represent the movement
of electron pairs.
(3)
(ii)
The reaction with 2-bromo-2-methylbutane proceeds by an SN1 mechanism.
Describe this mechanism using structural formulas and curly arrows to represent
the movement of electron pairs.
(3)
P a g e | 64
IB Chemistry - Topic 10 and 20 Guide
(iii)
Explain why 1-bromopentane reacts by an SN2 mechanism whereas 2-bromo-2methylbutane reacts by an SN1 mechanism.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(3)
(iv)
Explain whether the boiling point of 1-bromopentane will be higher, lower or the
same as that of 2-bromo-2-methylbutane.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(3)
(v)
The product C5H11OH formed from the reaction with 1-bromopentane is warmed
with ethanoic acid in the presence of a few drops of concentrated sulfuric acid.
State the name of the type of reaction taking place and the structural formula of the
organic product.
...........................................................................................................................
...........................................................................................................................
(2)
P a g e | 65
IB Chemistry - Topic 10 and 20 Guide
(c)
If the conditions of the reaction in (b) are changed so that a hot solution of sodium
hydroxide in ethanol is used then a different reaction occurs. The reaction with 2-bromo2-methylbutane gives two different organic products. State the type of reaction taking
place and suggest the identity (name or structure) of these two products.
Explain whether or not they can exist as geometrical isomers.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(4)
(Total 21 marks)
12.
Dihalogenoalkanes can react with warm dilute potassium hydroxide solution to form diols.
These diols can react with dicarboxylic acids.
(i)
Deduce the equation for the reaction of benzene-1,4-dicarboxylic acid with the diol
formed from 1,5-dibromopentane.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(3)
P a g e | 66
IB Chemistry - Topic 10 and 20 Guide
(ii)
Outline the economic importance of the reaction of diols with dicarboxylic acids.
......................................................................................................................................
......................................................................................................................................
(1)
(Total 4 marks)
13.
What is the IUPAC name of CH3CH2CONH2?
A.
Aminopropanal
B.
Ethanamide
C.
Propylamine
D.
Propanamide
(Total 1 mark)
14.
What is the main organic product formed from the reaction of CH3CH2OH with
CH3CH2CH2COOH in the presence of an acid catalyst?
A.
Ethyl butanoate
B.
Butyl ethanoate
C.
Ethyl propanoate
D.
Propyl ethanoate
(Total 1 mark)
P a g e | 67
IB Chemistry - Topic 10 and 20 Guide
15.
What are some uses of esters?
I.
Flavouring agents
II.
Perfumes
III.
Solvents
A.
I and II only
B.
I and III only
C.
II and III only
D.
I, II and III
(Total 1 mark)
16.
How many isomers can exist for a compound with the molecular formula C2H2Cl2?
A.
1
B.
2
C.
3
D.
4
(Total 1 mark)
P a g e | 68
IB Chemistry - Topic 10 and 20 Guide
17.
(a)
Below are four structural isomers with molecular formula C4H9Br. State the name of
each of the isomers A, B, C and D.
(4)
(b)
(i)
Identify the isomer(s) which will react with aqueous sodium hydroxide almost
exclusively by an SN1 mechanism. State the meaning of the symbols in the term
SN1 mechanism.
(2)
(ii)
Using the formula RBr to represent a bromoalkane, state an equation for the rate
determining step of this SN1 reaction.
(1)
(iii)
Identify one isomer that will react with aqueous sodium hydroxide almost
exclusively by an SN2 mechanism. Draw the mechanism for this reaction using
curly arrows to represent the movement of electron pairs. Include the structural
formulas of the transition state and the organic product.
(4)
P a g e | 69
IB Chemistry - Topic 10 and 20 Guide
(c)
State and explain how the rates of the reactions in parts (b) (i) and (b) (iii) are affected
when the concentration of the sodium hydroxide is doubled.
(2)
(d)
State and explain how the rate of reaction of 1-bromobutane with sodium hydroxide
compares with that of 1-chlorobutane with sodium hydroxide.
(2)
(e)
Identify the isomer of C4H9Br that can exist as stereoisomers. Outline how a polarimeter
will distinguish between the isomers, and how their physical and chemical properties
compare.
(5)
(f)
(i)
State the type of reaction that occurs when isomer B, CH3CHBrCH2CH3, reacts
with a hot alcoholic solution of sodium hydroxide.
(1)
(ii)
Explain how the reaction in part (f) (i) occurs by drawing the mechanism, using
curly arrows to represent the movement of electron pairs and identify the two
possible organic products.
(4)
(Total 25 marks)
18.
What is the IUPAC name for the following compound?
CH3(CH2)2COOCH3
A.
Methyl butanoate
B.
Butyl ethanoate
C.
Butyl methanoate
D.
Methyl propanoate
(Total 1 mark)
P a g e | 70
IB Chemistry - Topic 10 and 20 Guide
19.
What is the product of the following reaction?
Ni
CH3CH2CH2CN + 2H2 
A.
CH3CH2CH2NH2
B.
CH3CH2CH2CH2NH2
C.
CH3CH2NH2
D.
CH3CH2CH2CH3
(Total 1 mark)
20.
How many chiral carbon atoms are present in a molecule of 2,3-dibromobutane?
A.
1
B.
2
C.
3
D.
4
(Total 1 mark)
A.
CH3CH2CH2NH2
B.
CH3CH2CH2CH2NH2
C.
CH3CH2NH2
D.
CH3CH2CH2CH3
(Total 1 mark)
P a g e | 71
IB Chemistry - Topic 10 and 20 Guide
21.
Existence of isomers leads to diversity of organic compounds.
(a)
Describe what is meant by the term stereoisomers.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
(b)
1,3-dichlorocyclobutane exists as geometrical isomers, a form of stereoisomers.
(i)
Draw and name the two geometrical isomers of 1,3-dichlorocyclobutane.
...........................................................................................................................
(2)
(ii)
Identify the isomer with the higher boiling point and explain your reasoning.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(3)
(Total 7 marks)
P a g e | 72
IB Chemistry - Topic 10 and 20 Guide
22.
Halogenoalkanes undergo two major types of reaction leading to the formation of different
organic compounds.
(i)
1-bromopropane can be converted to 1-butylamine (butan-1-amine) in two stages.
Draw the structural formulas of 1-bromopropane and 1-butylamine (butan-1-amine).
(1)
(ii)
Deduce a reaction pathway for the two-stage conversion of 1-bromopropane to 1butylamine (butan-1-amine). Your answer should include an equation for each stage of
the reaction and the reaction conditions for the second stage.
(4)
(Total 5 marks)
23.
(i)
Describe the elimination of HBr from bromoethane. Your answer should include the
reagents, conditions and equation for the reaction.
(3)
(ii)
Explain the mechanism for the elimination of HBr from bromoethane.
(5)
(Total 8 marks)
24.
By which reactants and type of reaction can ethylamine (aminoethane) be produced?
Reactants
Type of reaction
A.
CH3Br + NH3
Nucleophilic substitution
B.
CH3CH2Br + NH3
Reduction
C.
CH3CN + H2
Nucleophilic substitution
D.
CH3CN + H2
Reduction
(Total 1 mark)
P a g e | 73
IB Chemistry - Topic 10 and 20 Guide
25.
Which compound is an amide?
A.
CH3COOCH3
B.
CH3CONH2
C.
CH3NH2
D.
CH2(NH2)COOH
(Total 1 mark)
26.
Which process can produce a polyester?
A.
Addition polymerization of a dicarboxylic acid
B.
Condensation polymerization of a diol and a dicarboxylic acid
C.
Addition polymerization of a diol and dicarboxylic acid
D.
Condensation polymerization of a dicarboxylic acid
(Total 1 mark)
27.
Which statement about stereoisomers is correct?
A.
1,2-dichloroethane has two geometrical isomers.
B.
1,2-dichloroethane has two optical isomers.
C.
1,2-dichloroethene has two geometrical isomers.
D.
1,2-dichloroethene has two optical isomers.
(Total 1 mark)
28.
(a)
There are four structural isomers with the molecular formula C4H9Br. One of these
structural isomers exists as two optical isomers. Draw diagrams to represent the threedimensional structures of the two optical isomers.
(2)
P a g e | 74
IB Chemistry - Topic 10 and 20 Guide
(b)
All the isomers can by hydrolysed with aqueous sodium hydroxide solution. When the
reaction of one of these isomers, X, was investigated the following kinetic data were
obtained.
Experiment
Initial [X] /
mol dm–3
Initial [OH–] /
mol dm–3
Initial rate of reaction /
mol dm–3 min–1
1
2.0 × 10–2
2.0 × 10–2
4.0 × 10–3
2
2.0 × 10–2
4.0 × 10–2
4.0 × 10–3
3
4.0 × 10–2
4.0 × 10–2
8.0 × 10–3
(i)
Deduce the rate expression for the reaction.
(3)
(ii)
Determine the value of the rate constant for the reaction and state its units.
(2)
(iii)
State the name of isomer X and explain your choice.
(2)
(iv)
State equations for the steps that take place in the mechanism of this reaction and
state which of the steps is slow and which is fast.
(2)
(Total 11 marks)
29.
Identify the functional group present in HCOCH2CH3.
A.
Ester
B.
Ketone
C.
Aldehyde
D.
Alcohol
(Total 1 mark)
P a g e | 75
IB Chemistry - Topic 10 and 20 Guide
30.
What is the IUPAC name for HCOOCH2CH2CH3?
A.
Butanoic acid
B.
Butanal
C.
Methyl propanoate
D.
Propyl methanoate
(Total 1 mark)
31.
Which statements about substitution reactions are correct?
I.
The reaction between sodium hydroxide and 1-chloropentane predominantly
follows an SN2 mechanism.
II.
The reaction between sodium hydroxide and 2-chloro-2-methylbutane
predominantly follows an SN2 mechanism.
III.
The reaction of sodium hydroxide with 1-chloropentane occurs at a slower rate
than with 1-bromopentane.
A.
I and II only
B.
I and III only
C.
II and III only
D.
I, II and III
(Total 1 mark)
32.
What is the organic product of the reaction between methylamine and ethanoic acid?
A.
CH3COONH4
B.
CH3NHCOCH3
C.
CH3COCH2NH2
D.
CH3CH2CONH2
(Total 1 mark)
P a g e | 76
IB Chemistry - Topic 10 and 20 Guide
33.
Which compound can exist as stereoisomers?
A.
CH3CH2CHO
B.
CH3CH2COCH3
C.
CH3CH(CH3)2
D.
CH3CH2CHOHCH3
(Total 1 mark)
34.
(a)
But-1-ene and 1-aminobutane (1-butylamine) can both be prepared from 1-bromobutane.
(i)
State the equation (using structural formulas) and the necessary reagents and
conditions for the preparation of but-1-ene from 1-bromobutane.
(3)
(ii)
Identify the type of reaction and explain the mechanism for the preparation of but1-ene from 1-bromobutane using curly arrows to represent the movement of
electron pairs.
(3)
(iii)
State the equation (using structural formulas) for the preparation of 1-aminobutane
from 1-bromobutane. State the necessary reagents and conditions of the reaction.
(3)
(iv)
Explain the mechanism for the preparation of 1-aminobutane from 1-bromobutane
using curly arrows to represent the movement of electron pairs.
(4)
P a g e | 77
IB Chemistry - Topic 10 and 20 Guide
(b)
2-bromobutane and 2-bromo-2-methylpropane are two isomers of 1-bromobutane.
(i)
Draw the structures of the two mirror images of the isomer that can exhibit optical
isomerism.
(2)
(ii)
Describe how the two optical isomers can be distinguished practically using planepolarized light.
(2)
(iii)
Explain why the mechanism of the reaction will be different if 1-bromobutane is
replaced by 2-bromo-2-methylpropane to form 2-amino-2-methylpropane in the
reaction in part (a)(iv).
(3)
(Total 20 marks)
35.
One form of nylon has the repeating unit:
(i)
Identify the circled functional group.
(1)
(ii)
Deduce the structures of the two monomers used to make this form of nylon.
(2)
P a g e | 78
IB Chemistry - Topic 10 and 20 Guide
(iii)
Nylon is a condensation polymer. Another condensation polymer can be formed by
reacting ethane-1,2-diol with benzene-1,4-dicarboxylic acid.
Deduce the equation for this reaction using n moles of each reactant.
(2)
(Total 5 marks)
36.
What is the organic product of the reaction between CH3CH2NH2 and CH3CH2COOH?
A.
CH3CH2NHCOCH2CH3
B.
CH3CH2CH2NHCOCH3
C.
CH3CH2NHCOCH3
D.
CH3NHCOCH3
(Total 1 mark)
37.
What is the IUPAC name of the compound CH3CH2COOCH2CH3?
A.
Ethyl ethanoate
B.
Propyl ethanoate
C.
Ethyl propanoate
D.
Pentyl propanoate
(Total 1 mark)
P a g e | 79
IB Chemistry - Topic 10 and 20 Guide
38.
Which statement is correct about the enantiomers of a chiral compound?
A.
Their physical properties are different.
B.
All their chemical reactions are identical.
C.
A racemic mixture will rotate the plane of polarized light.
D.
They will rotate the plane of polarized light in opposite directions.
(Total 1 mark)
39.
Deduce a two-step synthesis for each of the following conversions. For each step, state the
structural formulas of all reactants and products and state the conditions used in the reactions.
(i)
Ethanol to ethyl ethanoate.
(2)
(ii)
Propene to propanone.
(2)
(Total 4 marks)
40.
The reagents used in an elimination reaction are shown below.
Explain the mechanism of this reaction using curly arrows to represent the movement of
electron pairs.
(Total 3 marks)
P a g e | 80
IB Chemistry - Topic 10 and 20 Guide
41.
(i)
Describe geometrical isomerism.
(1)
(ii)
Draw the geometrical isomers of but-2-ene.
(2)
(iii)
Draw the two enantiomers of butan-2-ol.
(2)
(Total 5 marks)
42.
Which reaction occurs via a free-radical mechanism?
A.
C2H6 + Br2 → C2H5Br + HBr
B.
C2H4 + Br2 → C2H4Br2
C.
C4H9I + OH– → C4H9OH + I–
D.
(CH3)3CI + H2O → (CH3)3COH + HI
(Total 1 mark)
43.
Which compound could rotate the plane of polarization of polarized light?
A.
(CH3)2CHCH2Cl
B.
CH3CH2CH2CH2Cl
C.
CH3CH2CHClCH3
D.
(CH3)3CCl
(Total 1 mark)
P a g e | 81
IB Chemistry - Topic 10 and 20 Guide
44.
What is the name of the ester formed when CH3CH2COOH and CH3OH react together?
A.
Ethyl methanoate
B.
Methyl ethanoate
C.
Propyl methanoate
D.
Methyl propanoate
(Total 1 mark)
45.
Which formula represents a polyamide?
A.
( CH2–CHCl ) n
B.
( NH–(CH2)6–NH–CO–(CH3)4–CO ) n
C.
( CF2–CF2 ) n
D.
( O–(CH2)2–O–CO–
–CO ) n
(Total 1 mark)
46.
The compound C4H7Cl can exhibit stereoisomerism.
(i)
Draw the structural formulas of the two geometrical isomers of 1-chloro-but-2-ene.
(2)
(ii)
Explain why 1-chloro-but-2-ene shows geometrical isomerism.
(1)
(iii)
Draw the structural formula of one isomer of C4H7Cl that shows optical isomerism and
identify the chiral carbon atom with an asterisk (*).
(2)
(Total 5 marks)
P a g e | 82
IB Chemistry - Topic 10 and 20 Guide
47.
The compound but-2-ene-1,4-dioic acid forms two geometrical isomers which have different
physical and chemical properties.
(i)
Explain the difference in the melting points of the two isomers.
(3)
(ii)
Outline how the two isomers behave differently when gently heated.
(1)
(Total 4 marks)
48.
The reaction between bromoethane, CH3CH2Br, and potassium cyanide is an example of a
nucleophilic substitution reaction.
(i)
State whether this reaction is SN1 or SN2.
(1)
(ii)
Explain the mechanism of the reaction using curly arrows to represent the movement of
electron pairs.
(4)
(iii)
The organic product obtained in part (ii) can be reduced to form an amine.
State an equation for the reaction, naming the catalyst involved.
(2)
(Total 7 marks)
49.
Bromoethane reacts with potassium hydroxide to undergo mainly a substitution reaction or an
elimination reaction depending on the reaction conditions used.
(i)
State an equation and the reaction conditions used to control the products formed in each
case.
(4)
(ii)
Explain the mechanism of the elimination reaction using curly arrows to represent the
movement of electron pairs.
(4)
P a g e | 83
IB Chemistry - Topic 10 and 20 Guide
(iii)
Under certain conditions, the major product obtained in the elimination reaction can
undergo polymerization. Identify the type of polymerization this major product undergoes.
(1)
(Total 9 marks)
50.
What is the product of the following reaction?
Ni
CH3CH2CH2CN + H2 
A.
CH3CH2CH2NH2
B.
CH3CH2CH2CH3
C.
CH3CH2CH2CH2CH3
D.
CH3CH2CH2CH2NH2
(Total 1 mark)
51.
What is the correct IUPAC name for the following compound?
CH 3 CHCH 2 CH 2 CN
CH 3
A.
4-methylbutanenitrile
B.
4-methylpentanenitrile
C.
2-methylbutanenitrile
D.
2-methylpentanenitrile
(Total 1 mark)
P a g e | 84
IB Chemistry - Topic 10 and 20 Guide
52.
What is the organic product of the reaction between ethanol and ethanoic acid in the presence of
sulfuric acid?
A.
CH3CHO
B.
CH3COOCH3
C.
CH3CH2COOCH3
D.
CH3COOCH2CH3
(Total 1 mark)
53.
Which compound can exist as optical isomers?
A.
H2NCH2COOH
B.
H3CCONH2
C.
H3CCHBrI
D.
HCOOCH3
(Total 1 mark)
54.
The molecular formula, C3H4Cl2 represents several isomeric compounds. Some isomers are
cyclic and some are unsaturated.
(a)
Draw the structures of two cyclic compounds that are structural isomers and state the
names of both isomers.
(2)
P a g e | 85
IB Chemistry - Topic 10 and 20 Guide
(b)
Two of the non-cyclic compounds have geometrical isomers. Draw the structures of these
compounds and their geometrical isomers.
(2)
(Total 4 marks)
55.
The compound, 2-bromobutane, CH3CHBrCH2CH3, can react with sodium hydroxide to form
compounds F, G and H.
Compound F, C4H10O, exists as a pair of optical isomers. Compounds G and H, C4H8, are
structural isomers, and compound H exists as a pair of geometrical isomers.
(i)
Draw the structures of the two optical isomers of F.
(2)
(ii)
Outline the use of a polarimeter in distinguishing between the optical isomers.
(2)
(iii)
Draw diagrams to show the shapes of the two geometrical isomers of H.
(2)
(iv)
Draw the mechanism, using curly arrows to represent the movement of electron pairs, to
show the formation of G.
(3)
(Total 9 marks)
56.
A compound, J, has the molecular formula C2H4O2 and is obtained from a reaction between
methanoic acid and methanol. Write an equation for this reaction and state the name of
compound J.
(Total 3 marks)
P a g e | 86
IB Chemistry - Topic 10 and 20 Guide
Topic 10 SL Mark Scheme Past exam paper questions:
1.
C
[1]
2.
B
[1]
3.
C
[1]
4.
B
[1]
5.
(a)
(b)
boiling points increase (from the first member to the fifth member);
increasing size of molecule/area of contact/number of electrons (from
the first to the fifth member);
strength of intermolecular/van der Waals’/London/dispersion forces
increase / more energy required to break the intermolecular bonds
(from first member to fifth member);
same general formula;
successive members differ by CH2;
same functional group / similar/same chemical properties;
gradual change in physical properties;
Accept specific physical property such as melting point, boiling
point only once.
3
2 max
[5]
P a g e | 87
IB Chemistry - Topic 10 and 20 Guide
6.
A:
B:
C:
1,2-dichloroethane;
D:
Accept condensed formulas.
Penalize missing hydrogens only once.
5
[5]
7.
add bromine water/bromine;
pentane no change/stays brown and pent-1-ene decolourizes bromine
water/bromine;
OR
add acidified KMnO4;
pentane no change/stays purple and pent-1-ene decolourizes acidified KMnO4;
Accept any correct colour change.
Do not accept “clear” instead of “colourless”.
2 max
[2]
P a g e | 88
IB Chemistry - Topic 10 and 20 Guide
8.
E: primary and F: secondary;
G: primary;
G / E: only one alkyl group/2 H atoms attached to the carbon atom
attached to the Cl / only one carbon atom attached to the carbon atom
attached to the Cl;
F: two alkyl groups/1 H atom attached to the carbon atom attached to
the Cl / two carbon atoms attached to the carbon atom attached to the Cl;
4
[4]
9.
Initiation:
UV/ hf / hv / heat
 2Cl•;
Cl2    
Reference to UV/hf/hν/heat must be included.
Propagation:
Cl• + CH4 → CH3• + HCl;
CH3• + Cl2 → CH3Cl + Cl•;
Termination:
Cl• + Cl• → Cl2 / CH3• + Cl• → CH3Cl / CH3• + CH3• → C2H6;
Allow representation of radical without • (e.g. Cl, CH3) if consistent
throughout mechanism.
If representation of radical (i.e. •) is inconsistent, penalize once only.
4
[4]
P a g e | 89
IB Chemistry - Topic 10 and 20 Guide
10.
Accept condensed formulas.
Award [1 max] if A and D are other way round (and nothing else correct).
Award [2 max] if A and D are other way round but one substitution product
B or E is correct based on initial choice of A and D.
Award [3 max] if A and D are other way round but both substitution
products B and E are correct based on initial choice of A and D.
M2 (for B) and M5 (for E) may also be scored for substitution product
if primary chloroalkane used.
Penalize missing hydrogens once only.
5
[5]
P a g e | 90
IB Chemistry - Topic 10 and 20 Guide
11.
(i)
curly arrow going from lone pair/negative charge on O in HO– to C;
Do not allow curly arrow originating on H in HO–.
curly arrow showing Cl leaving;
Accept curly arrow either going from bond between C and Cl to Cl in
2-chloro-3-methylbutane or in the transition state.
representation of transition state showing negative charge, square
brackets and partial bonds;
Do not penalize if HO and Cl are not at 180° to each other.
Do not award M3 if OH ---- C bond is represented.
formation of organic product 3-methylbutan-2-ol and Cl–;
(ii)
OH– has a negative charge/higher electron density;
greater attraction to the carbon atom (with the partial positive
charge) / OWTTE;
Do not allow just greater attraction.
4
2
[6]
12.
B
[1]
13.
D
[1]
14.
D
[1]
15.
C
[1]
P a g e | 91
IB Chemistry - Topic 10 and 20 Guide
P a g e | 92
IB Chemistry - Topic 10 and 20 Guide
16.
(i)
(ii)
(iii)
addition of bromine/bromine water;
the bromine colour remains with propane and propene
decolourizes the bromine / solution changes from brown to colourless;
Do not accept “clear” instead of “colourless”.
addition (polymerization);
( CH(CH3)–CH2 ) / –CH(CH3)CH2–;
Continuation bonds necessary for mark, displayed formula or
condensed structural formula can be given.
Accept if more than one repeating unit is shown.
hydrogenation (of vegetable oils) / manufacture of margarine /
manufacture of ethanol / addition of water;
Accept manufacture of alcohol.
Do not accept hydrogenation of alkenes.
2
2
1
[6]
17.
1
O2 → 3CO2 + 4H2O / 2C3H8O + 9O2 → 6CO2 + 8H2O
2
Award [1] for correct products and reactants and [1] for correct
balancing.
Ignore state symbols.
(i)
C3H8O + 4
2
(ii)
acidic solution / H+ / sulfuric acid;
warm / heat / reflux;
(the solution changes) from orange to green;
3
(iii)
CH3CH2CHO and propanal;
CH3CH2COOH and propanoic acid;
CH3COCH3 and propanone/acetone;
Award [1] for 2 or 3 correct names or structures, award [2] for
4 or 5 correct names or structures.
propan-1-ol gives propanal and propanoic acid and propan-2-ol
gives propanone;
propan-1-ol has two H atoms bonded to the C containing the
–OH whereas propan-2-ol only has one / propan-1-ol is a primary
alcohol and propan-2-ol is a secondary alcohol;
5
[10]
18.
B
P a g e | 93
IB Chemistry - Topic 10 and 20 Guide
[1]
19.
(a)
correct isomer 3D structure;
correct name;
correct enantiomer 3D structure;
If compound incorrectly named award [2 max] for two correct 3D
enantiomers, and [1 max] for a correct structure of an enantiomer not
shown in 3D.
If non-optically active isomers given (e.g. 2-bromo-2-methyl-butane)
award [1 max] if name and 3D structure are correct.
Accept condensed form for alkyl chain throughout.
P a g e | 94
3
IB Chemistry - Topic 10 and 20 Guide
(b)
(i)
curly arrow going from lone pair/negative charge on O in
HO– to C bonded to Br;
Do not allow curly arrow originating on H in HO– (e.g. originating
on negative charge on H, i.e. lone pair/negative charge must be on O).
curly arrow from C–Br bond to form Br– (this can also be
shown in transition state);
transition state showing overall negative charge;
Accept condensed formulas as long as curly arrows can
still be shown, e.g.
3
If wrong formula used for halogenoalkane, e.g. 1-bromobutane
award [2 max].
P a g e | 95
IB Chemistry - Topic 10 and 20 Guide
(ii)
curly arrow from C–Br bond to form Br–;
correct structure of tertiary carbocation;
curly arrow going from lone pair/negative charge on O
in HO– to C+;
If non-bonding pair not shown then arrow must originate from
negative sign on O or the minus sign.
Only penalize arrow from H once in (b).
If wrong formula is used for 2-bromo-2-methylbutane
award [2 max].
(iii)
(iv)
(v)
3
the C bonded to the Br in 1-bromopentane is also bonded
to two H atoms so can accommodate five groups around it
in the transition state / OWTTE;
the C bonded to the Br in 2-bromo-2-methylbutane has
three other (bulky) groups bonded to it so cannot
accommodate five groups around it in the transition state /
OWTTE;
2-bromo-2-methylbutane forms a tertiary carbocation
which is stabilized by the positive inductive effect of the
three alkyl groups / OWTTE;
1-bromopentane would form a primary carbocation (if it
went by SN2) which is much less stable as there is only
one alkyl group exerting a positive inductive effect / OWTTE;
3 max
the boiling point of 1-bromopentane is higher than the
boiling point of 2-bromo-2-methylbutane;
2-bromo-2-methylbutane is more spherical in shape / less
surface area in contact between molecules of 2-bromo2-methylbutane than between molecules of 1-bromopentane /
OWTTE;
hence weaker intermolecular forces of attraction/van der
Waals’ forces of attraction between molecules of 2-bromo2-methylbutane / OWTTE;
3
esterification / condensation;
CH3–CO–O–(CH2)4CH3 / CH3COO(CH2)4CH3 /
CH3COOCH2CH2CH2CH2CH3 /
2
Accept CH3–CO–O–C5H11
P a g e | 96
IB Chemistry - Topic 10 and 20 Guide
(c)
elimination;
neither can exist as geometrical isomers as they contain the
same two groups/atoms on one of the double bonded carbon
atoms / OWTTE;
4
[21]
20.
D
[1]
21.
B
[1]
22.
B
[1]
23.
A
[1]
24.
(i)
Accept lines, dots or crosses for electron pairs.
Lone pairs required on chlorine.
(approximately)120°;
Accept any bond angle in the range 113–120°.
P a g e | 97
2
IB Chemistry - Topic 10 and 20 Guide
(ii)
(iii)
Brackets not required for mark.
Allow correct condensed structural formula.
Continuation bonds from each carbon are required.
Cl atoms can be above or below carbon spine or alternating
above and below.
1
plastics are cheap/versatile/a large industry / plastics have
many uses / OWTTE;
plastics are not biodegradeable / plastics take up large amounts of space in
landfill / pollution caused by burning of plastics / OWTTE;
Do not accept plastics cause litter.
Allow plastics don’t decompose quickly / OWTTE.
2
[5]
25.
(i)
Step 1:
CH2CHCl + H2 → CH3CH2Cl;
Step 2:
CH3CH2Cl + OH– → CH3CH2OH + Cl–;
Allow NaOH or NaCl etc. instead of OH– and Cl–.
Allow abbreviated formulas C2H3Cl, C2H5Cl, C2H5OH.
(ii)
H2SO4/H+/acidified and Cr2O72–/(potassium/sodium) dichromate;
Accept suitable oxidizing agents (e.g. KMnO4 etc.) but only with acid.
Ignore missing or incorrect oxidation states in reagents.
(heat under) reflux;
Second mark can be scored even if reagent is incorrect.
P a g e | 98
2
2
IB Chemistry - Topic 10 and 20 Guide
(iii)
CH3COOH(aq) + H2O(l)
CH3COO–(aq) + H3O+(aq)
OR
CH3COOH(l) + H2O(l)
CH3COO–(aq) + H3O+ (aq)
OR
CH3COOH(aq)
CH3COO–(aq) + H+(aq)
correct equation;
state symbols and
;
BL acid is CH3COOH and cb is CH3COO– / BL acid is H3O+ and cb is H2O;
3
[7]
26.
same general formula;
same functional group;
successive members differ by CH2;
Allow methylene for CH2.
similar chemical properties;
gradually changing physical properties;
2 max
[2]
27.
(a)
P a g e | 99
(i)
A: butan-1-ol;
B: butan-2-ol;
C: (2-)methylpropan-2-ol;
D: (2-)methylpropan-1-ol;
Accept answers in the form of 1-butanol and 2-methyl-2-propanol etc.
Penalize incorrect punctuation, e.g. commas for hyphens, only once.
4
(ii)
C/(2-)methylpropan-2-ol;
1
(iii)
A/butan-1-ol;
1
(iv)
B/butan-2-ol;
1
IB Chemistry - Topic 10 and 20 Guide
(v)
1
(b)
(i)
SN2;
1
(ii)
curly arrow going from lone pair/negative charge on O in OH– to C;
Do not allow curly arrow originating on H in OH–.
curly arrow showing Br leaving;
Accept curly arrow either going from bond between C and Br to Br in
1-bromobutane or in the transition state.
representation of transition state showing negative charge, square
brackets and partial bonds;
Do not penalize if HO and Br are not at 180° to each other.
Do not award third mark if OH----C bond is represented.
3
[12]
28.
LDPE: free radical mechanism;
HLPE: use of a Ziegler-Natta catalyst / ionic mechanism / coordination
polymerization;
2
[2]
P a g e | 100
IB Chemistry - Topic 10 and 20 Guide
29.
B
[1]
30.
A
[1]
31.
B
[1]
32.
(i)
(ii)
colour change from yellow/orange/rust colour/red/brown to colourless;
No mark for change to clear, or for decolourized with no reference
to original colour.
1
Chloroethene:
No mark if the lone pairs missing on Cl.
Accept lines, dots or crosses for e– pairs.
Poly(chloroethene):
;
n and square brackets are not required.
Continuation bonds must be shown.
(iii)
2
(hydration of ethene for the manufacture of) ethanol/ C2H4 + H2O → C2H5OH;
(synthesis of) CH3COOH /ethanoic/acetic acid;
(synthesis of) ethylene glycol/1,2-ethanediol/ethane-1,2-diol;
(synthesis of) drugs/pesticides;
(hydrogenation of unsaturated oils in the manufacture of) margarine;
Accept other commercial applications.
2 max
[5]
P a g e | 101
IB Chemistry - Topic 10 and 20 Guide
P a g e | 102
IB Chemistry - Topic 10 and 20 Guide
33.
(i)
Penalize missing H atoms once only.
(ii)
2
CH3CH=CHCH3 + H2O → CH3CH(OH)CH2CH3;
concentrated sulphuric acid/ H2SO4 and heat/steam / phosphoric acid/H3PO4
(catalyst) and heat/steam;
3CH3CH(OH)CH2CH3 + Cr2O72– + 8H+ → 3CH3COCH2CH3 + 2Cr3+ + 7H2O;
Accept CH3CH(OH)CH2CH3 + [O] → CH3COCH2CH3 + H2O .
Accept C2H5 as CH2CH3.
dichromate(VI) (ion)/Cr2O72– and acidic/H+;
Accept MnO4– in place of Cr2O72– in third and fourth marks.
heat/reflux;
5
[7]
34.
(i)
CH3CH2CH2OH, propan-1-ol/1-propanol;
CH3CH(OH)CH , propan-2-ol/2-propanol;
Need both formula and name for mark.
Accept either condensed or full structural formulas.
CH3CH2CH2OH: primary and CH3CH(OH)CH3: secondary;
(ii)
3
CH3CH2CHO;
CH3CH2COOH;
CH3COCH3;
Accept either condensed or full structural formulas.
from propan-1-ol: CH3CH2CHO(propanal) obtained by distillation (as
product is formed);
propan-1-ol gives CH3CH2COOH (propanoic acid) by (heating under) reflux;
Award [1] if CH3CH2CHO and CH3CH2COOH identified but conditions
not given/incorrect.
propan-2-ol gives CH3COCH3 by heat / reflux;
5 max
[8]
P a g e | 103
IB Chemistry - Topic 10 and 20 Guide
35.
A
[1]
36.
B
[1]
37.
A
[1]
38.
C
[1]
39.
B
[1]
40.
(a)
(b)
methylpropene;
Accept 2-methylpropene.
1
(i)
brown/orange/yellow to colourless / bromine is decolorized;
1
(ii)
1,2-dibromo-2-methylpropane / 1,2-dibromomethylpropane / 1-bromo-2methylpropan-2-ol / 1-bromomethylpropan-2-ol;
Do not penalize missing commas, hyphens or added spaces.
Award [1] if structure and correct name are given for 2-bromo-2methylpropan-1-ol.
P a g e | 104
2
IB Chemistry - Topic 10 and 20 Guide
[4]
P a g e | 105
IB Chemistry - Topic 10 and 20 Guide
41.
(i)
(ii)
synthesis of materials not naturally available/plastics;
chemically unreactive materials produced;
wide range of uses/physical properties / versatile;
cheap;
large industry;
uses a limited natural resource;
Award [2] for any two.
2 max
addition;
1
Must show continuation bonds.
Ignore bracket around the 6 carbons.
Must have 6 carbons joined to each other along chain.
1
(iii)
(iv)
monomers are smaller molecules / have smaller surface area than polymers;
Accept monomers have lower molecular mass.
with weaker intermolecular/Van der Waals’/London/dispersion forces;
Accept opposite argument for polymers.
2
[6]
42.
chloroethane;
(electrophilic) addition;
Do not accept free radical/nucleophilic addition.
2
[2]
43.
(a)
(b)
P a g e | 106
81.7
18 .3
= 6.80 and nH =
= 18.1;
12.01
1.01
ratio of 1: 2.67 /1: 2.7;
C3H8;
No penalty for using 12 and 1.
3
C3H8;
1
nC =
IB Chemistry - Topic 10 and 20 Guide
(c)
(i)
(ii)
Br2 /bromine;
UV/ultraviolet light;
Accept hf/hv/sunlight.
2
Cr2O72– /MnO4– and acidified/ H+ /H3O+;
Accept names.
heat / reflux;
(d)
2
Initiation:
Br2 → 2Br•;
Propagation:
Br• + RCH3 → HBr + RCH2•;
RCH2• + Br2 → RCH2Br + Br•;
Termination: [1 max]
Br• + Br• → Br2;
RCH2• + Br• → RCH2Br;
RCH2• + RCH2• → RCH2CH2R;
Award [1] for any termination step.
Accept radical with or without • throughout.
Do not penalize the use of an incorrect alkane in the mechanism.
(e)
P a g e | 107
(i)
substitution and nucleophilic and bimolecular/two species in
rate-determining step;
Allow second order in place of bimolecular.
4 max
1
IB Chemistry - Topic 10 and 20 Guide
(ii)
curly arrow going from lone pair/negative charge on O in OH– to C;
Do not allow curly arrow originating on H in OH–
curly arrow showing Br leaving;
Accept curly arrow either going from bond between C and Br to Br in
bromoethane or in the transition state.
representation of transition state showing negative charge, square
brackets and partial bonds;
Do not penalize if HO and Br are not at 180° to each other.
Do not award M3 if OH ---- C bond is represented unless already
penalized in M1.
Do not penalize the use of an incorrect alkyl chain in the mechanism.
3
[16]
44.
(i)
(ii)
CH3OCH2CH;
CH3CHOHCH;
Allow more detailed structural formulas.
2
CH3CHOHCH3 has higher boiling point due to hydrogen bonding;
CH3OCH2CH3 has lower boiling point due to Van der Waals’/London/
dispersion/dipole-dipole forces;
hydrogen bonds in CH3CHOHCH are stronger;
Allow ecf if wrong structures suggested.
2 max
[4]
45.
A
[1]
46.
C
[1]
P a g e | 108
IB Chemistry - Topic 10 and 20 Guide
P a g e | 109
IB Chemistry - Topic 10 and 20 Guide
47.
C
[1]
48.
A
[1]
49.
(i)
(ii)
(iii)
butane < propanal < propan-1-ol;
butane has van der Waals’/London/dispersion forces;
propanal has dipole-dipole attractive forces;
propan-1-ol has hydrogen bonding;
imf marks are independent of the order.
Treat references to bond breaking as contradictions if the imfs are correct.
4
butane is least soluble;
it cannot form hydrogen bonds/attractive forces with water molecules;
2
propanal and propanoic acid;
3
(iv)
1
(v)
secondary (alcohol);
propanone / acetone;
2
[12]
P a g e | 110
IB Chemistry - Topic 10 and 20 Guide
P a g e | 111
IB Chemistry - Topic 10 and 20 Guide
50.
(i)
(ii)
hydrogen bromide / hydrobromic acid;
Do not accept HBr, as name is asked for.
1
sodium hydroxide / hydroxide ions (name required);
dilute and aqueous / dilute and warm / aqueous and warm;
2
(iii)
curly arrow from OH– to C atom;
Accept from lone pair or minus sign or O. Do not award marking point if
arrow originates from the H of OH–.
curly arrow from bond between C and Br to bromine atom on bromoethane
or the transition state;
transition state including negative charge and partial bonds;
(iv)
3
hydration of ethene / steam + ethene;
Allow equation
(ethanol used as) solvent/fuel/antiseptic/intermediate to form
other compounds;
2
[8]
51.
D
[1]
52.
C
[1]
53.
A
[1]
P a g e | 112
IB Chemistry - Topic 10 and 20 Guide
54.
C
[1]
55.
(i)
(ii)
(iii)
(iv)
(v)
(vi)
P a g e | 113
energy required to break (1 mol of) a bond in a gaseous molecule/state;
Accept energy released when (1 mol of) a bond is formed in a gaseous
molecule/state / enthalpy change when (1 mol of) bonds are made or
broken in the gaseous molecule/state.
average values obtained from a number of similar bonds/
compounds / OWTTE;
2
Bonds broken
(1)(C–C) + (1)(O–H) + (5)(C–H) + (1)(C–O) + (3)(O=O)
= (1)(347) + (1)(464) + (5)(413) + (1)(358) + (3)(498) = 4728(kJ);
Bonds formed
(2 × 2)(C=O) + (3 × 2)(O–H)
= (4)(746) + (6)(464) = 5768 (kJ);
∆H = 4728 – 5768 = –1040 kJ mol–1 / –1040 kJ;
Units needed for last mark.
Award [3] for final correct answer.
Award [2] for +1040 kJ.
3
Mr(C2H5OH) = 46.08 / 46.1 and Mr(C8H18) = 114.26/114.3;
1 g ethanol produces 22.57 kJ and 1 g octane produces 47.88 kJ;
Accept values ranges of 22.5–23 and 47.8–48 kJ respectively.
No penalty for use of Mr = 46 and Mr = 114.
2
A: CH3CHO;
B: CH3COOH/CH3CO2H;
Accept either full or condensed structural formulas but not the
names or molecular formulas.
A: distillation;
B: reflux;
4
ethanol/CH3CH2OH;
hydrogen bonding (in ethanol);
Award second point only if the first is obtained.
2
(concentrated) H3PO4 /(concentrated) phosphoric acid / H2SO4/sulfuric acid;
dyes / drugs / cosmetics / solvent / (used to make) esters / (used in)
IB Chemistry - Topic 10 and 20 Guide
esterification/disinfectant;
2
[16]
56.
(i)
P a g e | 114
(2-)methylbutane / (2,2-)dimethylpropane;
1
IB Chemistry - Topic 10 and 20 Guide
(ii)
curly arrow going from O/lone pair of OH–(but not H) to the C attached to Br;
leaving of Br;
transition state representation with both Br and OH attached to C–1;
correct products CH3(CH2)4OH and Br–;
Charge must be shown for TS.
C–OH and C–Br bonds in TS must be represented by dashed lines.
4
[5]
57.
B
[1]
58.
A: CH3CHO;
B: CH3COOH/CH3CO2H;
Accept either full or condensed structural formulas but not the names
or molecular formulas.
A: distillation;
B: reflux;
4
[4]
59.
(concentrated) H2PO4/(concentrated) phosphoric acid / H2SO4/sulfuric acid;
dyes / drugs / cosmetics / solvent / (used to make) esters / (used in)
esterification / disinfectant;
2
[2]
P a g e | 115
IB Chemistry - Topic 10 and 20 Guide
P a g e | 116
IB Chemistry - Topic 10 and 20 Guide
60.
C
[1]
61.
A
[1]
62.
D
[1]
63.
C
[1]
64.
(a)
(i)
Isomer
Boiling point
A
B
C
36 °C
28 °C
10 °C
Award [1] if correct boiling points are assigned to 3 isomers.
(ii)
P a g e | 117
increase in branching / more side chains / more spherical shape /
reduced surface contact / less closely packed;
weaker intermolecular force/van der Waals’/London/dispersion forces;
Accept the opposite arguments
3
B: 2-methylbutane/methylbutane;
C: 2,2-dimethyl propane/dimethyl propane;
Do not penalize missing commas, hyphens or added spaces.
Do not accept 2-dimethylpropane, or 2,2-methylpropane.
2
IB Chemistry - Topic 10 and 20 Guide
(b)
C5H12;
Accept any two of the following explanations.
C5H11OH has greater molar mass / produces less grams of CO2 and
H2O per gram of the compound / suitable calculations to show this;
C5H11OH contains an O atom which contributes nothing to the energy
released / partially oxidized / OWTTE;
analogous compounds such as butane and butan-1-ol show a lower
value for the alcohol per mole in the data book / OWTTE;
the total bond strength in the pentanol molecule is higher than the total
bond strength in pentane;
the total amount of energy produced in bond formation of the products
per mole is the same;
fewer moles of pentanol in 1 g;
pentanol requires more energy to break intermolecular forces/
hydrogen bonding / OWTTE;
3 max
[8]
65.
(i)
C4H9Cl + KOH → C4H9OH + KCl;
1
(ii)
(substitution)
nucleophilic;
unimolecular / OWTTE;
2
1-chlorobutane:
SN2;
2-chloro-2-methylpropane:
SN1;
2
(iii)
P a g e | 118
IB Chemistry - Topic 10 and 20 Guide
(iv)
SN2 1-chlorobutane–allow ECF from (iii).
curly arrow going from lone pair or negative charge on O in OH– to C;
curly arrow for Cl leaving;
Can be shown in transition state.
formation of the transition state in bracket, with negative charge and dotted
lines to represent bonds;
SN1 2-chloro-2-methylpropane–allow ECF from (iii)
curly arrow showing Cl leaving;
formation of carbocation;
curly arrow from lone pair or negative charge on O in OH– to C+;
6
[11]
P a g e | 119
IB Chemistry - Topic 10 and 20 Guide
66.
(i)
Penalize missing H atoms once only.
Accept correct condensed structural formulas.
4
CH3–CH2–CH2–CHO / (CH3)2CHCHO;
CH3–CH2–CH2–COOH / (CH3)2CHCOOH;
2
(iii)
CH3–CH2–CO–CH3;
1
(iv)
orange to green;
1
(ii)
P a g e | 120
IB Chemistry - Topic 10 and 20 Guide
(v)
1
[9]
67.
B
[1]
68.
C
[1]
69.
A
[1]
70.
B
[1]
71.
A
[1]
72.
(a)
one general formula / same general formula;
differ by CH2;
similar chemical properties;
gradual change in physical properties;
1
Award [1] for any two of the above characteristics.
(b)
P a g e | 121
ethanol lower / ethanoic acid higher;
IB Chemistry - Topic 10 and 20 Guide
due to larger mass of ethanoic acid/stronger van der Waals’/
London/dispersion forces;
due to stronger hydrogen bonding/2 hydrogen bonds per molecule;
2
Accept either answer for second mark.
P a g e | 122
IB Chemistry - Topic 10 and 20 Guide
(c)
2
Allow condensed structural formulas such as
CH3CH2CH2CH2OH.
Award [2] for all three correct isomers, [1] for any two correct
isomers.
[5]
73.
(i)
(Empirical formula =) C8H8O3;
H
H
O
O
H C
C
H
H O
;
H
H
H
2
Allow double bonds on arene in alternate positions, or allow
delocalized representation (of pi electrons).
(ii)
(iii)
the bond at 0.1373 nm is a double bond and the bond at 0.1424 nm is a
single bond;
in CO2(g) both bonds are double bonds and would have a value
around 0.137 nm;
2
Ester;
Arene/benzene ring;
Alcohol;
2
Award [2] for any three correct, award [1] for any two correct.
Do not accept alkane as a type of functional group in this
molecule.
[6]
P a g e | 123
IB Chemistry - Topic 10 and 20 Guide
74.
(i)
(ii)
boiling point increases as the number of carbons increases / OWTTE;
Greater Mr and hence greater van der Waals’/London/dispersion
forces present;
2
hv / UV light
 CH3Cl + HCl;
CH4 + Cl2   
Do not award mark if hv/uv light is not given.
Initiation step:
hv / UV light
 2Cl•;
Cl2   
Do not award mark if hv/uv light is not given.
Penalize once only.
Propagation step:
CH4 + Cl• → CH3• + HCl;
CH3• + Cl2 → CH3Cl + Cl•;
Termination step:
Cl• + Cl•  Cl2 or Cl• + CH3•  CH3Cl or CH3• + CH3• → CH3CH3;
Allow fish-hook half-arrow representations i.e. use of
Penalize use of full curly arrows once only.
Penalize missing dots on radicals once only.
5
.
[7]
75.
(i)
A. = CH3(CH2)7CHO;
B. = CH3(CH2)7COOH/CH3(CH2)7CO2H;
C. = (CH3)3COH;
D. = (CH3)2CO;
E. = BrCH2CH2Br;
5
Allow correct structural formulas.
(ii)
addition;
/-(CH2-CH2)3-/-(CH2)6-;
2
[7]
P a g e | 124
IB Chemistry - Topic 10 and 20 Guide
Topic 10 HL Mark Scheme Past exam paper questions:
1.
D
[1]
dw2. B
[1]
3.
A
[1]
4.
A
[1]
5.
CH3CH2COOH + CH3OH
CH3CH2COOCH3 + H2O
[1] for reactants and [1] for products.
(concentrated) sulfuric acid/H2SO4;
Do not accept just H+ or acid.
methyl propanoate;
4
[4]
6.
(i)
curly arrow going from lone pair/negative charge on O in HO– to C;
Do not allow curly arrow originating on H in HO–.
curly arrow showing Cl leaving;
Accept curly arrow either going from bond between C and Cl to Cl in
P a g e | 125
IB Chemistry - Topic 10 and 20 Guide
2-chloro-3-methylbutane or in the transition state.
representation of transition state showing negative charge, square
brackets and partial bonds;
Do not penalize if HO and Cl are not at 180° to each other.
Do not award M3 if OH ---- C bond is represented.
formation of organic product 3-methylbutan-2-ol and Cl–;
(ii)
OH– has a negative charge/higher electron density;
greater attraction to the carbon atom (with the partial positive
charge) / OWTTE;
Do not allow just greater attraction.
4
2
[6]
7.
CH3CH2CH2CH2Cl + KCN → CH3CH2CH2CH2CN + KCl;
Accept CN– for KCN and Cl– for KCl.
pentanenitrile;
Allow 1-cyanobutane.
CH3CH2CH2CH2CN + 2H2 → CH3CH2CH2CH2CH2NH2;
pentan-1-amine / 1-aminopentane / 1-pentylamine / 1-pentanamine;
Catalyst: nickel/Ni / palladium/Pd / platinum/Pt;
Penalize missing hydrogen once only.
5
[5]
8.
C
[1]
9.
A
[1]
10.
B
[1]
P a g e | 126
IB Chemistry - Topic 10 and 20 Guide
11.
(a)
correct isomer 3D structure;
correct name;
correct enantiomer 3D structure;
If compound incorrectly named award [2 max] for two correct 3D
enantiomers, and [1 max] for a correct structure of an enantiomer not
shown in 3D.
If non-optically active isomers given (e.g. 2-bromo-2-methyl-butane)
award [1 max] if name and 3D structure are correct.
Accept condensed form for alkyl chain throughout.
P a g e | 127
3
IB Chemistry - Topic 10 and 20 Guide
(b)
(i)
curly arrow going from lone pair/negative charge on O in
HO– to C bonded to Br;
Do not allow curly arrow originating on H in HO– (e.g. originating
on negative charge on H, i.e. lone pair/negative charge must be on O).
curly arrow from C–Br bond to form Br– (this can also be
shown in transition state);
transition state showing overall negative charge;
Accept condensed formulas as long as curly arrows can
still be shown, e.g.
3
If wrong formula used for halogenoalkane, e.g. 1-bromobutane
award [2 max].
P a g e | 128
IB Chemistry - Topic 10 and 20 Guide
(ii)
curly arrow from C–Br bond to form Br–;
correct structure of tertiary carbocation;
curly arrow going from lone pair/negative charge on O
in HO– to C+;
If non-bonding pair not shown then arrow must originate from
negative sign on O or the minus sign.
Only penalize arrow from H once in (b).
If wrong formula is used for 2-bromo-2-methylbutane
award [2 max].
(iii)
(iv)
(v)
3
the C bonded to the Br in 1-bromopentane is also bonded
to two H atoms so can accommodate five groups around it
in the transition state / OWTTE;
the C bonded to the Br in 2-bromo-2-methylbutane has
three other (bulky) groups bonded to it so cannot
accommodate five groups around it in the transition state /
OWTTE;
2-bromo-2-methylbutane forms a tertiary carbocation
which is stabilized by the positive inductive effect of the
three alkyl groups / OWTTE;
1-bromopentane would form a primary carbocation (if it
went by SN2) which is much less stable as there is only
one alkyl group exerting a positive inductive effect / OWTTE;
3 max
the boiling point of 1-bromopentane is higher than the
boiling point of 2-bromo-2-methylbutane;
2-bromo-2-methylbutane is more spherical in shape / less
surface area in contact between molecules of 2-bromo2-methylbutane than between molecules of 1-bromopentane /
OWTTE;
hence weaker intermolecular forces of attraction/van der
Waals’ forces of attraction between molecules of 2-bromo2-methylbutane / OWTTE;
3
esterification / condensation;
CH3–CO–O–(CH2)4CH3 / CH3COO(CH2)4CH3 /
CH3COOCH2CH2CH2CH2CH3 /
2
Accept CH3–CO–O–C5H11
P a g e | 129
IB Chemistry - Topic 10 and 20 Guide
(c)
elimination;
neither can exist as geometrical isomers as they contain the
same two groups/atoms on one of the double bonded carbon
atoms / OWTTE;
4
[21]
12.
(i)
nHO–(CH2)5–OH + nHOOC–C6H4–COOH
→ H–[O–(CH2)5–O–CO–C6H4–CO–]n–OH + (2n – 1)H2O
3
Award [1] for correct reactants, [1] for correct polyester and
[1] for balanced water.
Award [3] if correct equation given for one molecule of diol
reacting with one molecule of dicarboxylic acid.
i.e.
HO–(CH2)5–OH + HOOC–C6H4–COOH → HO–(CH2)5–O–CO–C6H4–COOH + H2O
(ii)
formation of polyesters/condensation polymers/synthetic fabrics;
1
[4]
13.
D
[1]
14.
A
[1]
15.
D
[1]
P a g e | 130
IB Chemistry - Topic 10 and 20 Guide
16.
C
[1]
P a g e | 131
IB Chemistry - Topic 10 and 20 Guide
17.
(a)
(b)
A: l-bromobutane;
B: 2-bromobutane;
C: 2-bromo-2-methylpropane;
D: 1-bromo-2-methylpropane;
Penalize incorrect punctuation, e.g. commas for hyphens, only once.
Accept 2-bromomethylpropane and 1-bromomethylpropane for
C and D respectively.
(i)
(ii)
(iii)
4
C/2-bromo-2-methylpropane;
unimolecular nucleophilic substitution;
2
RBr → R+ + Br–;
Allow use of 2-bromo-2-methylpropane instead of RBr.
1
A/1-bromobutane/D/1-bromo-2-methylpropane;
curly arrow going from lone pair/negative charge on O in OH– to C;
Do not allow curly arrow originating on H in OH–.
curly arrow showing Br leaving;
Accept curly arrow either going from bond between C and Br to Br in
1-bromobutane or in the transition state.
representation of transition state showing negative charge, square
brackets and partial bonds;
Do not penalize if HO and Br are not at 180° to each other.
Do not award fourth mark if OH----C bond is represented.
(c)
P a g e | 132
(b)(i) no change as [OH–] does not appear in rate equation/in
the rate determining step;
(b) (iii) rate doubles as the rate is proportional to [OH–] / OH–
appears in the rate-determining/slow step / first order with
respect to OH–;
Award [1] if correctly predicts no rate change for SN1 and
doubling of rate for SN2 of without suitable explanation.
4
2
IB Chemistry - Topic 10 and 20 Guide
P a g e | 133
IB Chemistry - Topic 10 and 20 Guide
(d)
(e)
(f)
P a g e | 134
rate of 1-bromobutane is faster;
C–Br bond is weaker/breaks more easily than C–Cl bond;
2
2-bromobutane/B;
(plane-) polarized light shone through;
enantiomers rotate plane of plane-polarized light to left or right/
opposite directions (by same amount);
Accept “turn” instead of “rotate” but not “bend/reflect”.
physical properties identical (apart from effect on plane-polarized light);
chemical properties are identical (except with other chiral compounds);
Do not accept “similar” in place of “identical”.
5
(i)
1
elimination;
IB Chemistry - Topic 10 and 20 Guide
(ii)
curly arrow going from lone pair/negative charge on O in OH– to H on β-C;
Do not allow curly arrow originating on H in OH–.
Allow C2H5O– instead of OH–.
curly arrow going from CH bond to form C=C bond;
curly arrow showing Br leaving;
Accept the following for first 3 marks.
curly arrow showing Br leaving;
representation of carbocation;
curly arrow going from lone pair/negative charge on O in OH–
to H on C adjacent to C+ and curly arrow going from
CH bond to form C=C bond;
two products formed: but-1-ene / but-2-ene/(cis) but-2-ene/
(trans) but-2-ene;
Award [1] for two correct answers.
4 max
[25]
P a g e | 135
IB Chemistry - Topic 10 and 20 Guide
18.
A
[1]
19.
B
[1]
20.
B
[1]
21.
(a)
compounds with same structural formula;
Do not allow “same molecular or chemical formula without the
same structural formula”.
but different arrangement of atoms in space/spatial arrangement;
(b)
2
(i)
Cis(-1,3-dichlorocyclobutane)
(ii)
Trans(-1,3-dichlorocyclobutane)
Need clear cis/trans structure and name for each mark.
Award [1] for 2 correct structures without names.
2
cis (higher boiling point);
cis (more) polar / trans non-polar/less polar;
cis experiences stronger (permanent) dipole-dipole interaction / trans
experiences no/(much) less dipole-dipole interaction;
Do not accept just strong forces without reference to
dipole-dipole interaction.
3
[7]
P a g e | 136
IB Chemistry - Topic 10 and 20 Guide
P a g e | 137
IB Chemistry - Topic 10 and 20 Guide
22.
(i)
Accept CH3CH2CH2Br.
Penalize missing H atoms.
(ii)
Accept CH3CH2CH2CH2NH2.
1
CH3CH2CH2Br + KCN → CH3CH2CH2CN + KBr;
Accept ionic equation.
CH3CH2CH2CN + 2H2 → CH3CH2CH2CH2NH2;
Equation must be balanced for mark.
Accept LiAlH4 in place of reaction with hydrogen.
For the second equation:
Ni (as catalyst);
heat/150 °C;
4
[5]
23.
(i)
P a g e | 138
hot;
alcoholic OH– /NaOH/KOH;
C2H5Br + C2H5ONa → C2H4 + NaBr + C2H5OH /
C2H5Br + NaOH → C2H4 + NaBr + H2O;
Accept ionic equation with C2H5O– or OH–.
3
IB Chemistry - Topic 10 and 20 Guide
(ii)
OH– reacts with ethanol to form ethoxide ion/C2H5OH + OH– → C2H5O– + H2O;
curly arrow going from lone pair/negative charge on O in C2H5O– /CH3CH2O– to
H on β–C;
Accept arrow origin from OH– but do not allow curly arrow
originating on H in OH–.
Accept OH– in place of C2H5O–(to form H2O).
curly arrow going from CH bond to form C=C bond;
curly arrow showing Br leaving;
structural formula of organic product CH2=CH2;
Award [4 max] for E1 mechanism (unstable primary carbocation)
curly arrow showing Br leaving;
representation of primary carbocation;
curly arrow going from lone pair on O in H2O to H on C
adjacent to C+ and curly arrow going from CH bond to
form C=C bond;
structural formula of organic product CH2=CH2;
5
[8]
24.
D
[1]
25.
B
[1]
26.
B
[1]
P a g e | 139
IB Chemistry - Topic 10 and 20 Guide
27.
C
[1]
28.
(a)
First and second structures should be mirror images.
Tetrahedral arrangement around carbon must be shown.
(b)
(i)
(ii)
(iii)
(iv)
2
order with respect to OH– = 0;
order with respect to X = 1;
rate = k[X];
Award [3] for final correct answer.
3
0.2(0);
min–1;
2
2-bromo-2-methyl-propane;
Do not penalize missing hyphens or added spaces.
Accept 2-bromomethylpropane.
tertiary (structure);
2
C4H9Br → C4H9+ + Br– / in equation with curly arrows and slow;
C4H9+ + OH– → C4H9OH / in equation with curly arrows and fast;
No penalty if primary structure is shown.
No credit for SN2 mechanism, except by ECF.
2
[11]
29.
C
[1]
P a g e | 140
IB Chemistry - Topic 10 and 20 Guide
P a g e | 141
IB Chemistry - Topic 10 and 20 Guide
30.
D
[1]
31.
B
[1]
32.
B
[1]
33.
D
[1]
34.
(a)
P a g e | 142
(i)
CH3CH2CH2Br → CH3CH2CH=CH2 + HBr /
CH3CH2CH2CH2Br + OH– → CH3CH2CH=CH2 + H2O + Br–;
alcoholic NaOH/OH–;
reflux / heat;
Penalize missing Hs once only throughout the question
3
IB Chemistry - Topic 10 and 20 Guide
(ii)
elimination reaction;
Then accept either E1 or E2 mechanism.
E1
curly arrow showing bromine leaving the halogenoalkane;
OH– acting as base on the intermediate carbocation;
E2
curly arrow showing OH– acting as base on H bonded to C;
concerted curly arrows showing Br leaving C–Br;
(iii)
3
CH3CH2CH2CH2Br + NH3 → CH3CH2CH2CH2NH2 + HBr;
ammonia/NH3;
warm / excess ammonia (to prevent secondary amines etc.);
3
(iv)
curly arrow from ammonia (to form transition state);
correct transition state;
curly arrow from bond to Br atom in either the first or second step;
formation of HBr and organic product;
Accept a second molecule of NH3 removing H+ from the transition state
to give NH4+ and Br– as products.
P a g e | 143
4
IB Chemistry - Topic 10 and 20 Guide
(b)
(i)
(ii)
(iii)
Award [1] for correct structure and [1] for correct 3-D
representation of both enantiomers.
2
polarimeter (to measure angle of rotation);
the plane of plane-polarized light rotates in opposite directions
(by the different enantiomers);
2
2-bromo-2-methylpropane is tertiary / 1-bromobutane is primary;
2-bromo-2-methylpropane goes by SN1 / 1-bromobutane by SN2;
intermediate carbocation more stable for tertiary;
no space around tertiary carbon for five groups (in SN2
transition state);
3 max
[20]
35.
(i)
amide / peptide;
1
(ii)
H2N(CH2)6NH2;
HOOC(CH2)8COOH / ClOC(CH2)8COCl;
2
nHOOCC6H4COOH + nHOCH2CH2OH
→ HO--(--OCC6H4COOCH2CH2O--)n–H + (2n – 1)H2O;
Award [1] for correct organic product and [1] for (2n – 1)H2O.
Accept --(--OCC6H4COOCH2CH2O--)n— for the organic product.
2
(iii)
[5]
36.
A
[1]
P a g e | 144
IB Chemistry - Topic 10 and 20 Guide
37.
C
[1]
P a g e | 145
IB Chemistry - Topic 10 and 20 Guide
38.
D
[1]
39.
(i)
CH 3CH 2 OH
K Cr2 O 7
 CH3COOH 

 CH3CH2CH2CH3 + H2O
CH3CH2OH 2 
H+
H2SO4
Structural formulas of reactants and products
CH3CH2OH and CH3COOH/CH3CO2H and CH3CO2CH2CH3 (+ H2O);
Conditions/reagents used
reflux with named suitable acidified oxidizing agent and then heat with
alcohol and sulfuric acid;
Suitable oxidizing agents are potassium dichromate/K2Cr2O7 /
sodium dichromate/Na2Cr2O7 / dichromate/Cr2O72– / potassium
manganate(VII)/potassium permanganate/KMnO4 / permanganate/
manganate (VII)/MnO4–.
Accept H+/H2SO4 instead of sulfuric acid and acidified.
Award [1] for structural formulas of reactants and products and [1] for
the correct conditions/reagents used.
(ii)
2
2 2 7
2

 CH3CH(OH)CH3 
 (CH3)2CO
H2C=CH(CH3) 
H O
H2SO4(conc.)
K Cr O
H+
Structural formulas of reactants and products
H2C=CH(CH3) and CH3CH(OH)CH3 and (CH3)2CO;
Conditions/reagents used
water/H2O and sulfuric acid/H2SO4 / dilute acid medium and heat/reflux
with suitable acidified oxidizing agent;
Suitable oxidising agents are potassium dichromate/K2Cr2O7 / sodium
dichromate/Na2Cr2O7 / dichromate/Cr2O72– / potassium manganate(VII)/
potassium permanganate/KMnO4 / permanganate/manganate (VII)/MnO4–.
Accept H+/H2SO4 instead of acidified.
Note: If primary alcohol is given as product of first step, and everything
else correct, award [1 max].
Accept either full or condensed structural formulas throughout the question.
2
[4]
P a g e | 146
IB Chemistry - Topic 10 and 20 Guide
40.
curly arrow going from O of –OCH2CH3 attacking hydrogen;
Allow the curly arrow to originate from either the lone pair or O of –OCH2CH3 but
not from H of –OCH2CH3.
Do not award first mark if curly arrow originates from O of NaOCH2CH3.
curly arrow going from the C–H bond on the β carbon to the bond joining the
α carbon to the β carbon and curly arrow showing Br acting as leaving group;
formation of (CH3)2C=CH2 and Br–;
Allow formation of NaBr for third marking point, if was used (incorrectly)
in the mechanism. Use of NaOCH2CH3 with curly arrow originating on
O of NaOCH2CH3 is penalized already in the first marking point.
Accept alternative E1 type mechanism
curly arrow showing Br acting as leaving group to form carbocation;
curly arrow going from O of –OCH2CH3 attacking hydrogen;
formation of (CH3)2C=CH2 and Br–;
No marks awarded if a substitution mechanism is given.
3
[3]
41.
(i)
compounds with the same (molecular formula and) structural formula but
different arrangements of atoms in space / OWTTE;
1
(ii)
Allow [1 max] if structures are correct but arrangement of groups in space
does not clearly show the cis/ trans isomerism.
P a g e | 147
IB Chemistry - Topic 10 and 20 Guide
(iii)
Allow [1 max] if the structures are correct but it is not clear that they are
mirror images.
2
[3]
42.
A
[1]
43.
C
[1]
44.
D
[1]
45.
B
[1]
46.
(i)
2
P a g e | 148
IB Chemistry - Topic 10 and 20 Guide
(ii)
P a g e | 149
no rotation possible due to double bond/pi bond;
Accept hindered or restricted rotation.
1
IB Chemistry - Topic 10 and 20 Guide
(iii)
correct structural formula;
chiral carbon atom identified;
2
[5]
47.
(i)
(ii)
trans has the higher melting point;
trans isomer has (predominantly) intermolecular hydrogen bonding;
cis isomer has (predominantly) intramolecular hydrogen bonding;
3
cis isomer readily releases water (vapour forming a cyclic anhydride);
Accept opposite arguments for trans isomer.
1
[4]
48.
(i)
SN2;
1
(ii)
curly arrow going from CN– to C;
curly arrow showing Br leaving;
Curly arrow may be represented on transition state.
(iii)
representation of transition state, showing negative charge and dotted lines;
products;
4
CH3CH2CN + 2H2 → CH3CH2CH2NH2;
Ni / Pt / Pd;
2
[6]
P a g e | 150
IB Chemistry - Topic 10 and 20 Guide
49.
(i)
CH3CH2Br + OH– → CH3CH2OH + Br–;
CH3CH2Br + OH– → CH2=CH2 + H2O + Br–;
Accept KOH and KBr in the balanced equations
dilute KOH compared to concentrated KOH;
aqueous KOH compared to ethanolic KOH;
warm/40–50 °C compared to hot/80-100 °C;
Accept any two reaction conditions.
4 max
(ii)
(iii)
curly arrow from O to H;
curly arrow from C–H to C–C;
curly arrow showing Br leaving;
products CH2=CH2 + Br– + C2H5OH/H2O;
4
addition;
1
[9]
50.
D
[1]
51.
B
[1]
52.
D
[1]
53.
C
[1]
P a g e | 151
IB Chemistry - Topic 10 and 20 Guide
54.
(a)
Cl
Cl
and 1,1 dichlorocyclopropane;
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
(cis- or trans-) 1,2 dichlorocyclopropane;
2
Award point for the correct name corresponding to the related
isomer.
Accept diagrams that do not display 3 dimensional structure.
Award [1 max] for correct structures only, without the
corresponding names.
(b)
Cl
Cl
CH 3
Cl
and
H
Cl
H
CH 2 Cl
Cl
Cl
CH 3
H
and
H
H
H
CH 2 Cl
2
[4]
55.
(i)
OH
OH
C
CH3 CH2
H
CH3
H
CH3
C
CH2 CH 3
2
Award [2] for both tetrahedral structures, or [1] if tetrahedral
structure is not clear.
(ii)
P a g e | 152
plane polarized light;
rotation in opposite/different directions;
2
IB Chemistry - Topic 10 and 20 Guide
(iii)
CH 3
CH 3
C
C
;
H
H
CH 3
H
C
C
;
CH 3
H
2
(iv)
curly arrow showing attack by –OH on end H;
curly arrow showing C–Br bond fission;
curly arrow showing formation of double bond;
H2O and Br– shown as products;
3 max
Award [1] each for any three.
If but-2-ene formed, award [2 max].
[9]
56.
CH3OH + HCOOH  HCOOCH3 + H2O
Award [1] for both reactants and [1] for both products (accept
C2H4O2).
methyl methanoate;
3
[3]
P a g e | 153
IB Chemistry - Topic 10 and 20 Guide