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Candidate
Name
Centre
Number
Candidate
Number
2
GCE A level
334/01
CHEMISTRY CH4
P.M. THURSDAY, 21 January 2010
1 hour 40 minutes
FOR EXAMINER’S
USE ONLY
ADDITIONAL MATERIALS
Section Question
1
In addition to this examination paper, you will need:
• a calculator;
• an 8 page answer book;
• a Data Sheet which contains a Periodic Table supplied by WJEC.
Refer to it for any relative atomic masses you require.
A
INSTRUCTIONS TO CANDIDATES
B
Write your name, centre number and candidate number in the spaces
at the top of this page.
Mark
2
3
4
5
TOTAL MARK
Section A Answer all questions in the spaces provided.
Section B Answer both questions in Section B in a separate answer book which should then be placed
inside this question-and-answer book.
Candidates are advised to allocate their time appropriately between Section A (35 marks) and Section
B (40 marks).
INFORMATION FOR CANDIDATES
The number of marks is given in brackets at the end of each question or part-question.
The maximum mark for this paper is 75.
Your answers must be relevant and must make full use of the information given to be awarded full
marks for a question.
You are reminded that marking will take into account the Quality of Written Communication in all
written answers.
VP*(W10-334-01)
2
Examiner
only
SECTION A
Answer all the questions in the spaces provided.
1.
(a)
Naphtha, a mixture of hydrocarbons obtained from petroleum, can be oxidised under
suitable conditions. This gives a number of liquid products, including methanoic, ethanoic
and propanoic acids, together with propanone.
The compounds are separated from each other by fractional distillation.
(i)
Explain the meaning of the term fractional distillation.
[1]
....................................................................................................................................................................................................................
....................................................................................................................................................................................................................
(ii)
A sample of the propanone fraction is thought to contain a small quantity of
methanoic acid.
Some of this fraction is added to water and an acid-base indicator shows that the
mixture is acidic.
State the name of a suitable reagent that would confirm the presence of an acid in the
mixture and state what would be observed when this reagent was added.
[2]
Reagent
..............................................................................................................................................................................
Observation
.....................................................................................................................................................................
......................................................................................................................................................................................................
(b)
Ethanoic acid is the major product from the oxidation of naphtha described in (a).
Some of the ethanoic acid is reacted with chlorine, in a free-radical reaction, to produce
chloroethanoic acid.
CH3COOH + Cl2
CH2ClCOOH + HCl
State what is meant by the term free radical.
[1]
....................................................................................................................................................................................................................
....................................................................................................................................................................................................................
(c)
Aminoethanoic acid is produced from chloroethanoic acid in a reaction with ammonia.
(i)
In this reaction ammonia reacts as a nucleophile.
State what is meant by the term nucleophile.
[1]
....................................................................................................................................................................................................................
....................................................................................................................................................................................................................
(ii)
(334-01)
Give the formula of a nucleophile other than ammonia.
........................................................
[1]
3
Examiner
only
(d)
Aminoethanoic acid (glycine), CH2(NH2)COOH, exists largely as a zwitterion.
Give the graphic (full structural) formula for the zwitterion form of aminoethanoic acid. [1]
(e)
The formula below shows one of the two dipeptides formed from the reaction between
aminoethanoic acid and aminopropanoic acid.
HOOC
CH3 H
O
H
C
C
C
H
N
NH2
H
Draw the structural formula for the other dipeptide formed from these two amino acids. [1]
(334-01)
Turn over.
4
(f)
(i)
Examiner
only
An amide, Compound Z, can be represented by the formula shown below.
O
R
C
NH2
(R is an alkyl group)
Analysis of Compound Z showed that it contained 16.1% of nitrogen by mass.
Use this information to show that R could be a CH3CH2CH2— group.
(ii)
[2]
Give the graphic (full structural) formula of any isomer of CH3CH2CH2CONH2
(Compound Z), which is also an amide.
[1]
Total [11]
(334-01)
5
2.
(a)
Examiner
only
Propanal and propanone are isomers of molecular formula C3H6O.
(i)
The table below shows some of the reagents with which propanal and propanone
may be tested.
Complete the table, giving the expected observation(s).
If there is no observable reaction, write no reaction.
Tollens’ reagent
[Ag+ / NH3(aq)]
2,4-dinitrophenylhydrazine
[3]
acidified potassium
dichromate
propanal
propanone
(ii)
The mass spectra of both propanal and propanone show a molecular ion peak, M+,
at 58.
However, the mass spectrum of propanal shows a peak at m/z 29.
Give the formula of an ion responsible for this peak at m/z 29 and explain why
propanone is unlikely to give a peak at this value.
[2]
....................................................................................................................................................................................................................
....................................................................................................................................................................................................................
(b)
1,2-Diphenylethanone is a yellow solid.
(i)
O
O
C
C
State the general name of a group present in 1,2-diphenylethanone that is responsible
for the yellow colour.
[1]
....................................................................................................................................................................................................................
(ii)
Explain why this compound is yellow in white light.
[1]
....................................................................................................................................................................................................................
....................................................................................................................................................................................................................
(334-01)
Turn over.
6
(c)
Examiner
only
The wavelengths (λmax) at which two indicators absorb visible light are shown in the table.
Indicator
λmax / nm
methyl red
410
phenol red
423
State which of these two indicators absorbs light at a higher frequency, giving a reason for
your answer.
[2]
....................................................................................................................................................................................................................................
....................................................................................................................................................................................................................................
(d)
Methyl red is an azo dye.
Study the sequence below, which illustrates the formation of another azo dye, and answer
the questions that follow.
NH2
N2+Cl–
benzenediazonium chloride
phenylamine
an aqueous solution of
naphthalene-2-ol
red azo dye
(i)
State the reagent used in acidic solution, to produce benzenediazonium chloride
from phenylamine.
[1]
....................................................................................................................................................................................................................
(ii)
State a suitable temperature for the reaction described in (i).
(iii)
State, approximately, the pH of the aqueous solution of naphthalene-2-ol.
.............................................
.............................
[1]
[1]
Total [12]
(334-01)
7
3.
Examiner
only
Pheromones are substances released by insects and other animals to convey ‘messages’ to other
individuals.
(a)
4-Methylheptan-3-ol is a pheromone produced by the female of the beetle species
responsible for spreading Dutch elm disease.
H
(i)
H
H
H
H
H
H
H
C
C
C
C
C
C
C
H
H
H
CH3 OH H
H
H
Explain what is meant by a chiral centre.
[1]
....................................................................................................................................................................................................................
....................................................................................................................................................................................................................
(ii)
Identify any chiral centre in 4-methylheptan-3-ol by using an asterisk(*) in the
formula above.
[1]
(iii)
4-Methylheptan-3-ol can be oxidised to the ketone, 4-methylheptan-3-one.
H
CH3
CH2
CH2
C
C
CH2
CH3
CH3 O
Explain briefly, in terms of intermolecular bonding, why the boiling temperature of
4-methylheptan-3-ol is higher than the boiling temperature of 4-methylheptan-3-one.
A detailed description of the types of intermolecular bonding is not required.
[2]
....................................................................................................................................................................................................................
....................................................................................................................................................................................................................
....................................................................................................................................................................................................................
....................................................................................................................................................................................................................
(334-01)
Turn over.
8
(iv)
I
Examiner
only
One method of preparing an alkene is to eliminate water from a primary
alcohol (a dehydration reaction).
State the reagent that reacts with an alcohol in this reaction to produce an
alkene.
[1]
......................................................................................................................................................................................................
II
When 4-methylheptan-3-ol is dehydrated in a similar way, one product is
4-methylhept-2-ene.
CH3
CH2
CH2
CH
CH
CH
CH3
CH3
State, giving a reason, whether 4-methylhept-2-ene exists as geometric
(cis/trans) isomers.
[2]
......................................................................................................................................................................................................
......................................................................................................................................................................................................
(334-01)
9
(b)
Examiner
only
Compound G is a pheromone produced by the honey bee.
O
CH3
C
(CH2)5
CH
CH
COOH
Compound G
(i)
Give the shortened structural formula of the compound produced when Compound
G reacts with hydrogen gas in the presence of a nickel catalyst.
[1]
O
(ii)
A test for the presence of the CH3
group in a compound such as
C
R
Compound G is to react the compound with a mixture of aqueous sodium
hydroxide/iodine or aqueous potassium iodide and sodium chlorate(I).
State what is seen during this reaction and name the product that confirms the
presence of the above group.
Observation
Name
(iii)
...........................................................................................................................................................
.........................................................................................................................................................................
[1]
[1]
Both ketones and carboxylic acids can be completely reduced using lithium
tetrahydridoaluminate(III) (lithium aluminium hydride), LiAlH4.
Complete the structure below, showing all the bonds present, for the final organic
product when Compound G is reduced in this way.
[2]
(CH2)5
CH
CH
Total [12]
Total Section A [35]
(334-01)
Turn over.
10
SECTION B
Answer both questions in the separate answer book provided.
4.
(a)
The nitration of methylbenzene gives 1-methyl-2-nitrobenzene as the main product.
CH3
CH3
NO2
The mechanism for this reaction is similar to the nitration of benzene.
(i)
Give the mechanism for the nitration of methylbenzene to give
1-methyl-2-nitrobenzene.
In your answer you should
• state the starting reagents other than methylbenzene,
• show the mechanism starting with the nitronium ion (nitryl cation), NO2+, and
methylbenzene,
• state the type of mechanism occurring.
[4]
(ii)
I
Under certain conditions 1-methyl-2-nitrobenzene will rearrange to give its
isomer 2-aminobenzenecarboxylic acid.
CH3
COOH
NO2
NH2
Use the Data Sheet to describe how the characteristic peaks in the infrared
spectrum of 2-aminobenzenecarboxylic acid would differ from those of
1-methyl-2-nitrobenzene.
In your answer you should clearly identify the bonds present and the
frequencies corresponding to them.
[3]
II
(334-01)
2-Aminobenzenecarboxylic acid, unusually for an aromatic compound, is very
soluble in water. One reason for this solubility is its ability to hydrogen bond
with water molecules.
Describe how this compound forms hydrogen bonds with water, illustrating
your answer with a diagram.
[3]
11
(b)
(i)
Kevlar is a polyamide that is used in bullet-proof vests.
Its structure can be represented as follows.
H
H
O
O
N
N
C
C
n
Give the graphical (full structural) formulae of the two reactants used to make
Kevlar.
[2]
(ii)
(c)
4-Aminobenzenecarboxylic acid can be polymerised to give a polyamide.
Give the graphical (full structural) formula of a section of this condensation polymer
and state how it differs from the structure of Kevlar.
[2]
The local anaesthetic benzocaine is the ethyl ester of 4-aminobenzenecarboxylic acid.
O
H2N
C
O
CH2
CH3
Esters such as benzocaine can be made in the same way as esters of simple carboxylic
acids.
(i)
Write the equation for the preparation of benzocaine starting from
4-aminobenzenecarboxylic acid.
[2]
(ii)
Describe how the impure benzocaine can be recrystallised from ethanol to give pure
dry crystals that melt at 91°C.
(iii)
Your method should mention any essential safety methods that are needed.
[3]
Explain why benzocaine can act as a base.
[1]
Total [20]
(334-01)
Turn over.
12
5.
(a)
2-Ethanoyloxybenzenecarboxylic acid (aspirin) is an ester of ethanoic acid.
O
O
C
CH3
COOH
Aspirin
(i)
Aspirin can be made in the laboratory by reacting
2-hydroxybenzenecarboxylic acid and ethanoyl chloride.
O
OH
O
ethanoyl chloride
CH3
COOH
(ii)
(b)
C
COOH
I
The mixture obtained from this reaction is added to water to remove excess
ethanoyl chloride.
Give the equation for the reaction of ethanoyl chloride with water.
[2]
II
Before purification the crude aspirin contained some unreacted
2-hydroxybenzenecarboxylic acid.
Describe a chemical test to show that a solution of this impure aspirin
contained 2-hydroxybenzenecarboxylic acid.
[2]
III
In an experiment 0.0500 mol of 2-hydroxybenzenecarboxylic acid gave 5.85 g
of pure aspirin.
Calculate the percentage yield of pure aspirin.
[4]
Describe, in outline, how aspirin is made in industry, starting from phenol.
[4]
Some antiseptics used in the home contain chlorinated phenols such as
2,6-dichloro-4-methylphenol.
CH3
Cl
Cl
OH
The reaction of this compound with hot aqueous sodium hydroxide shows, as with
chlorobenzene, that it is difficult to remove the chlorine in this way, by hydrolysis.
Explain why this is relatively difficult to achieve when compared to the alkaline hydrolysis
of 1-chlorobutane.
In your answer you should refer to the hydrolysis reaction of both compounds.
(334-01)
[3]
13
(c)
1-Chlorobutane can be made by the following reaction.
CH3CH2CH2CH3 + Cl2
CH3CH2CH2CH2Cl + HCl
The mechanism for this reaction, free-radical substitution, is similar to the reaction of
methane with chlorine.
The mass spectrum of the product shows the presence of an impurity having a relative
molecular mass of 114.
Give a molecular formula for this impurity and suggest how it could be formed during this
reaction.
[2]
(d)
(i)
Give the graphic (full structural) formula of the two branched-chain isomers of
1-chlorobutane.
[2]
(ii)
Only one of the two branched-chain isomers of 1-chlorobutane in (i) will give an
NMR spectrum showing only a single unsplit peak.
State and explain which one of these isomers will give this NMR spectrum.
[1]
Total [20]
Total Section B [40]
(334-01)
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