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CHEMISTRY (PAPER 2)
Chemical change ................................................................................................................................................................................. 3
Endothermic and Exothermic Reactions ........................................................................................................................................ 3
Rate of Reactions ............................................................................................................................................................................ 4
Collision Theory .......................................................................................................................................................................... 4
Reaction Rate ............................................................................................................................................................................. 4
Measuring Rate .......................................................................................................................................................................... 4
Boltzmann Distribution of energy .................................................................................................................................................. 5
Equilibrium ..................................................................................................................................................................................... 6
Open and closed systems ........................................................................................................................................................... 6
Reversable Reactions ................................................................................................................................................................. 6
Dynamic Equillibrium ................................................................................................................................................................. 6
Le Chatelier’s Principal ............................................................................................................................................................... 6
Equilibrium Constant (KC) ........................................................................................................................................................... 6
KW ............................................................................................................................................................................................... 7
KA ................................................................................................................................................................................................ 7
Electrochemical Reactions .................................................................................................................................................................. 8
Voltaic or Galvanic ..................................................................................................................................................................... 8
Electrolytic ...................................................................................................................................................................................... 9
Definitions ...................................................................................................................................................................................... 9
Standard Hydrogen Electrode ...................................................................................................................................................... 10
Organic Chemistry ............................................................................................................................................................................. 11
Naming Organic Molecules (IUPAC Names) ................................................................................................................................. 11
Dienes....................................................................................................................................................................................... 12
Alcohols .................................................................................................................................................................................... 13
Aldehydes ................................................................................................................................................................................. 14
Ketones .................................................................................................................................................................................... 14
Carboxylic Acid ......................................................................................................................................................................... 14
Haloalkanes .............................................................................................................................................................................. 14
Esters ........................................................................................................................................................................................ 14
Addition Reactions ....................................................................................................................................................................... 15
Hydrohalogenation .................................................................................................................................................................. 15
Halogenation ............................................................................................................................................................................ 15
Hydration ................................................................................................................................................................................. 15
Hydrogenation ......................................................................................................................................................................... 15
Elimination Reactions ................................................................................................................................................................... 15
Dehydrohalogentaion .............................................................................................................................................................. 15
© Samir Daniels
Chemistry
Page 1
Dehydration ............................................................................................................................................................................. 15
Cracking .................................................................................................................................................................................... 15
Substitution Reactions .................................................................................................................................................................. 15
Interconversion ........................................................................................................................................................................ 15
The Chemical Industry ...................................................................................................................................................................... 16
SASOL ............................................................................................................................................................................................ 16
Hydrocracking .......................................................................................................................................................................... 16
Steam cracking ......................................................................................................................................................................... 16
Fractional distillation ................................................................................................................................................................ 16
The Chloralkali Industry .................................................................................................................................................................... 16
Uses .............................................................................................................................................................................................. 16
The Fertiliser Industry ....................................................................................................................................................................... 17
Manufacturing .............................................................................................................................................................................. 17
Batteries ............................................................................................................................................................................................ 17
Leclanché dry cell ......................................................................................................................................................................... 17
Zinc chloride dry cell ..................................................................................................................................................................... 17
Alkaline dry cell............................................................................................................................................................................. 17
Mercury Battery ........................................................................................................................................................................... 17
Lithium Ion Battery ....................................................................................................................................................................... 17
Lead-acid storage battery ............................................................................................................................................................. 17
Data booklet ..................................................................................................................................................................................... 18
© Samir Daniels
Chemistry
Page 2
CHEMICAL CHANGE
ENDOTHERMIC AND EXOTHERMIC REACTIONS

For an endothermic reaction:
o The temperature of the surroundings decreases because the kinetic energy is being transferred to break
bonds.
o The temperature decreases because it takes in energy.
o Temperature: T ↓
o Bond energy: E ↑
ΔH>0
(Positive)



o Here the graph shows that it takes more energy to break bonds than to make bonds.
For an exothermic reaction:
o Temperature of the surroundings increase because making bonds create energy
o E↓
o T↑
The activated complex is the nature when all bonds between the reactants have been broken, before any bonds of the
products have been created.
The activation energy (𝐸𝐴 ) is the amount of energy required to break all bonds before a chemical reaction can take
place. The reactants need sufficient 𝐸𝐾 to bring upon a chemical reaction.
© Samir Daniels
Chemistry
Page 3
RATE OF REACTIONS
COLLISION THEORY


Particles can only react when they are in contact with one another.
The reaction rate is therefore determined by the number of and frequency of the collisions that is made
REACTION RATE


The reaction rate is the speed at which a reaction takes place
Factors that affect rate of reactions:
O Surface area (of a solid)
 A greater surface area increases the likelihood of a molecule colliding and reacting
 ↑ S.A - ↑reaction rate
O Concentration (of a solution)
 Higher concentration means there are more reactant molecules per unit of volume, which means that
molecules find it easier to collide with the substance
 ↑ Concentration – ↑ reaction rate
O Pressure (of a gas)
 Easier to collide
 ↑ Concentration – ↑ reaction rate
O Temperature
 An increase in temperature means the molecules’ speed increase and will increase the number of
collisions per second
O Addition of a catalyst
 The catalyst holds the molecule into place until another molecule reacts with is.
 Adding a catalyst – ↑ reaction rate
O Nature of reactants

The dotted line shows the increased reaction rate.
MEASURING RATE





Change in temperature
Change in colour
Change in mass of the reaction vessel
Measuring gas volumes
(Pressure gauge)
Turbidity (precipitate formed)
vs. time
© Samir Daniels
Chemistry
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C HANGE IN M ASS
C HANGE IN VOLUME
Measured using a scale
Measure the mass of the reaction vessel.
Measured using a gas syringe or pressure gauge
BOLTZMANN DISTRIBUTION OF ENERGY
The very hot particles (at the end) will escape 1 and the 𝐸𝐾 will decrease because only the cooler (particles with less 𝐸𝐾 will be
left over.
1
Change state
© Samir Daniels
Chemistry
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EQUILIBRIUM
OPEN AND CLOSED SYSTEMS
A system in which both energy and matter can be changed with surrounding is called an open system.
A system in which only energy but not matter can be exchange with the surrounding is called a closed system.
REVERSABLE REACTIONS
𝐴+𝐵 ⇌𝐶+𝐷
In a chemical equilibrium, the concentrations of reactants and
products do not change. But the forward and reverse reactions have
not stopped - they are still going on at the same rate as each other.
DYNAMIC EQUILLIBRIUM
A dynamic equilibrium is a chemical equilibrium between a forward
reaction and the reverse reaction where the rate of the reactions are
equal.
LE CHATELIER’S PRINCIPAL
When the conditions (temperature, concentration or pressure) under a closed system is disturbed, the system acts in
such a way as to oppose the change.
The equilibrium shifts in the direction that opposed it.
→ If the temperature increases, the system will try to get colder
Three possible changes can upset the equilibrium:



Temperature
o Decrease in temperature will favour the exothermic reaction
Concentration
o If the concentration is increased, the equilibrium shifts in the opposite direction
(away from)
Pressure
o A decrease in pressure will favour the reaction which has an increase in volume
EQUILIBRIUM CONSTANT (KC )
For the reaction:
aA + bB ⇌ cC + dD
a → No. of Moles (balancing number)
A → Molecule
KC =
[C]c [D]d
[A]a [B]b
[A] means the concentration of A


Only molecules in the liquid phase
i.e. no solids

No H2O
If KC > 1 then it Favours Product
If KC < 1 then it favours the Reactant
© Samir Daniels
Chemistry
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S OLVING K C P ROBLEMS
1.
2.
Write out full balanced equation
Construct nstart , nreacted , nequilibrium , concentration table`
3.
4.
Fill in all known values
See what the question is asking and solve.
aA
a
No. of moles
nstart
nreact
nequilibrium
Concentration
+bB
b
This goes with the ratio coefficients
C=
⇌ cC
c
nstart − nreact
n
v

If the products (C and D) are higher, i.e. K C > 1, it will favour the products

K C is affected by:
o Temperature
o Pressure (gas)
NH3 used as fertilizers and cleaning products
Production can be sped up by lowering temperature or increasing H 2 or N2


+dD
d
KW
K W measures how easily H2O splits up into H+ and OH- ions
H2 O ⇌ H+ + OH(hydrogen Ion) (Hydroxide Ion)
2H2 O ⇌ H3 O+ + OH-

(Hydronium)

If a chemical releases more H+ ions into a solution,
it is an ACID
1 × 10−3 [H+ ] ≡ pH of 3  Acidic

Adding OH- will shift the equilibrium to
the left, producing less H+ ions
KW > 7  Alkali
K W = [H3 O+ ][OH- ] = [H+ ][OH- ]
= 1 × 10−14
o
∴ [H+ ] = 1 × 107
− log(1 × 107 ) = 7 = pH of H+ in H2 O
KA

Acid Dissociation Constant

All acids donate H+ ions
o Monotropic
o Can only donate one hydrogen
o
o

© Samir Daniels
Chemistry
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Because this area has a big area of
negative charge, the H+ ion does not
dissociate easily, which means it is not a
strong acid.
ELECTROCHEMICAL REACTIONS
VOLTAIC OR GALVANIC

Converts chemical energy into electrical energy


Dipped in an electrolyte
o
Zn|Zn2+ ||Ag+ |Ag
 Anode first
Oxidation is written on the left
o
 Zn → Zn2+ + 2eReduction is on the right
o

o
Ag+ + e- → Ag
Zn + Ag+ + e- → Ag + Zn2+ + 2e-
C ALCULATE E 0 C ELL :
1. Identify two half reactions
2. Write the most positive one above the other
3. Draw


around them
Top is forward reaction (ANODE)
Bottom is reverse reaction (CATHODE)
4. Identify oxidation or reduction
5. Solve
Solid|Aqueous||Aqueous|Solid
© Samir Daniels
Chemistry
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STANDARD CONDITIONS:
1 atm (gasses)
1 M (solutions)
25° C (temp) (298K)
Otherwise 𝑝𝑉 = 𝑛𝑅𝑇
ELECTROLYTIC




Converts electrical energy into chemical potential energy
Electrode reactions sustained by a supply of electrical energy
For the electrode to become positive i.e. if you want the negatively charged ion to be attracted to the electrode, attach
it to the positive terminal
O e- gets sucked away from the electrode attached to the +ve terminal.
O
O

−
𝐴2+
𝑎𝑞 + 2𝑒 → 𝐴𝑠
𝐵(𝑠) →
2+
𝐵(𝑎𝑞)
+ 2𝑒
Reduction
−
Oxidation
Electrorefining
DEFINITIONS
OXIDATION: LOSS OF ELECTRONS happens at the ANODE
REUCTION: GAIN OF ELECTRONS happens at the CATHODE
Mass of cathode ↑
Mass of anode ↓
AN OX
Anode → Oxidation
RED CAT
REDuction → CAThode
OIL RIG
Oxidation if Lost / Reduction if Gain
Oxidant (Oxidising agent) – causes another to be oxidised, which means it gains electrons
Reductant (Recuing agent) – causes another to be reduced, which means is loses electrons.
© Samir Daniels
Chemistry
Page 9
STANDARD HYDROGEN ELECTRODE
H2 O → H+ + OH2H+ + 2e- → H2(g)
OH- + Na+ → NaOH
© Samir Daniels
Chemistry
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ORGANIC CHEMISTRY
The chemistry of carbon
NAMING ORGANIC MOLECULES (IUPAC NAMES)
*Alphabetical Preference
No. of Carbon
1
Name
Meth-
2
Eth-
3
Prop-
4
But-
5
Pent-
6
Hex-
7
Hept-
8
Oct-
9
Non-
10
Dec-
Single Bonds between
Carbon
–ane
Structure
Alkanes 𝐶𝑛 𝐻2𝑛+2
Double bonds
between Carbons
–ene
Triple bonds between
Carbons
–yne
Alkenes 𝐶𝑛 𝐻2𝑛
Alkynes 𝐶𝑛 𝐻2𝑛−2
© Samir Daniels
Chemistry
Page 11
When finding the name of a molecule,
1.
2.
3.
Identify the longest chain of carbons2.
Locate3 any double or triple bonds
Locate any additional substituents4



There’s only one Carbon → MethThere’s 2 chlorines → dichlorIt’s single bonds → -ane
o Dichloromethane

Alkane + O2 → H2O + CO2 Δ H < 0 (exothermic)
DIENES

Conjugated
o Separated by a single bond

o
Cumulated
o Two double bonds to one carbon

o
but-2,3- diene
Isolated
o More than one saturated carbon bonds between two double bonds
o
hex-2,4-diene
but-1,4-diene
Homogolous Series → a group of compounds with the same general formula
2
Gives you the root (meth-, eth- )
Numbered position
4
Something extra (clhoro-)
3
© Samir Daniels
Chemistry
Page 12
Isomers → different structure, but same empirical formula


The longer the chain of Carbon, the higher the fixed points (melting and boiling points)
Stronger inter-molecular forces will have high boiling points (more energy to break bonds)
Functional series → double or triple bonds are functional groups. They are ‘add-ons’ that change the chemistry of a carbon
chain
ALCOHOLS
Suffix



-ol
Methanol
Ethanol
Hex-3,3-diol
T YPES OF ALCOHOLS
Primary Alcohol
Secondary Alcohol
Tertiary Alcohol

The number of carbons surrounded by the hydroxide determines the type of alcohol.
© Samir Daniels
Chemistry
Page 13
ALDEHYDES
Suffix


Methanal
Butanal


Prop-2-one
Hex-2,3-dione


Methanoic acid
Pentanoic acid
-al
KETONES
Suffix
-one
CARBOXYLIC ACID
Suffix:
-ic acid
HALOALKANES
Prefix:
Where X is any halogen (Chlorine, Fluorine,
Bromine, etc)
halo-
chloro-
fluoro-



Flouroethane
2-bromo-1,3-dichloropentane
Tetrachloromethane



Alcohol + carboxylic acid → ester + water
Ethanol + Butanoic acid → butyl ethanoate + water
Methanol + Hexanoic acid → hexyl methanoate
ESTERS
An ester is the product of an alcohol and a
carboxylic acid
Done under acidic conditions

Saturated → alkane bonds, where carbons make one bond only
Unsaturated → carbons have more than one bond
© Samir Daniels
Chemistry
Page 14
ADDITION REACTIONS
Unsaturated compounds undergo addition reactions
HYDROHALOGENATION

HX + alkene
o Hydrochloric acid + but-1-ene → butyl-1-chloride

→
+
HALOGENATION

X2 + alkene
o F2 + But-1-ene → butyl-1,2-difluoride

→
+
HYDRATION

H2O + alkene → Alcohol
o But-1-ene + water → butan-1-ol
o
+
→
HYDROGENATION

H2 + alkene → Alkane
o But-1-ene + Hydrogen gas → butane
o
+
→
ELIMINATION REACTIONS
Saturated compounds undergo elimination reactions

DEHYDROHALOGENTAION


Elimination of HX from a haloalkane
Heat under reflux in a concentrated solution of
NaOH or KOH
SUBSTITUTION REACTIONS
INTERCONVERSION
DEHYDRATION


Elimination of H2O from an alcohol
Heating of alcohol with excess concentration
H2SO4


Tertiary alcohols only
Just add HX to produce a haloalkane

Reactions of bases with haloalkanes (hydrolysis)
produces alcohols

Haloalkanes from alkanes
CRACKING


Or low pressure and temperature with catalyst
Breaking up large hydrocarbon molecules into
smaller and more useful bits
High pressure and temperature without catalyst
© Samir Daniels
Chemistry
Page 15
THE CHEMICAL INDUSTRY
SASOL

Use Coal Gasification to produce liquid fuels
HYDROCRACKING

Hydrocracking is a cracking process that is assisted by the presence of an elevated partial pressure of hydrogen gas. It
produces chemical products such as ethane, LPG, isoparaffins, jet fuel and diesel.
STEAM CRACKING

Steam cracking occurs under very high temperatures. During the process, a liquid or gaseous hydrocarbon is diluted
with steam and then briefly heated in a furnace at a temperature of about 850°. Steam cracking is used to convert
ethane to ethylene. Ethylene is a chemical that is needed to make plastics. Steam cracking is also used to make
propylene, which is an important fuel gas.
FRACTIONAL DISTILLATION

Fractional distillation is the separation of a mixture into its component parts, or fractions. Since air is made up of a
number of gases (with the major component being nitrogen), fractional distillation can be used to separate it into these
different parts
THE CHLORALKALI INDUSTRY


Production of Chlorine and Sodium Hydroxide
Through the electrolysis of sodium chloride (NaCl) – saturated in the form of brine.
USES


Chlorine is used to purify watrer
Cleaning agent
The membrane cell:
© Samir Daniels
Chemistry
Page 16
THE FERTILISER INDUSTRY


A fertiliser is a compound that is given to a plant to promote growth. Fertilisers usually provide the three major plant
nutrients and most are applied via the soil so that the nutrients are absorbed by plants through their roots.
NPK Ratio is the percentage of nitrogen, phosphorous and potassium in the fertiliser
MANUFACTURING



Ammonia → Haber Process
Nitric Acid → Ostwald Process
Sulphuric Acid → Contact process
Pg 195 Everything Science.
BATTERIES
LECLANCHÉ DRY CELL








Zinc-carbon dry cell
The electrolyte consists of an ammonium chloride paste
Electrodes are made of zinc and carbon
Zinc forms the anode
Manganese forms the cathode
Powdered carbon is used in the cathode to improve conductivity and retain moisture
Anode: 𝑍𝑛 → 𝑍𝑛2 + + 2𝑒 −
Cathode: 2𝑁𝐻4+ + 2𝑀𝑛𝑂2 + 2𝑒 − → 𝑀𝑛2 𝑂3 + 2𝑁𝐻3 + 𝐻2 𝑂
ZINC CHLORIDE DRY CELL






Zinc-carbon dry cell
Electrolyte is zinc chloride
Manganese forms the cathode
ALKALINE DRY CELL


MERCURY BATTERY
LITHIUM ION BATTERY

Potassium hydroxide as the electrolyte
Lasts much longer than dry cells

LEAD-ACID STORAGE BATTERY




Small battery used in watches
Zinc anode
Steel cathode
12V used in cars
Contains six cells connected in series
Led anode
Lead oxide cathode
© Samir Daniels
Chemistry
Page 17
Lithium ions move back and forth between
positive and negatie electrodes
Can be recharged
DATA BOOKLET
Standard pressure
Pθ
1,013 x 105 Pa
Molar gas volume at STP
Vm
22,4 dm3∙mol-1
Standard temperature
Tθ
273 K
n
m
M
q=It
c
m
n
or c 
V
MV
Eθcell  Eθcathode  Eθanode
θ
Eθcell  Ereduction
 Eθoxidation
W = Vq
θ
Eθcell  Eθoxidisingagent  Ereducing
agent
© Samir Daniels
Chemistry
Page 18