Q1.
Ethanol is produced commercially by fermentation of aqueous glucose, C6H12O6
State two conditions, other than temperature, which are necessary for fermentation.
Explain why neither a low temperature nor a high temperature is suitable for this reaction.
Give two advantages of this method of production over that by the direct hydration of ethene.
Write an equation for the production of ethanol by fermentation and an equation for the complete
combustion of ethanol.
(Total 8 marks)
Q2.
(a) Gas oil (diesel), kerosine (paraffin), mineral oil (lubricating oil) and petrol (gasoline) are
four of the five fractions obtained by the fractional distillation of crude oil within the
temperature range 40–400 °C.
Identify the missing fraction and state the order in which the five fractions are removed as
the fractionating column is ascended. Give two reasons why the fractions collect at
different levels in the fractionating column.
(4)
(b)
Thermal cracking of large hydrocarbon molecules is used to produce alkenes. State the
type of mechanism involved in this process. Write an equation for the thermal cracking of
C21H44 in which ethene and propene are produced in a 3:2 molar ratio together with one
other product.
(3)
(c)
Write equations, where appropriate, to illustrate your answers to the questions below.
(i)
Explain why it is desirable that none of the sulphur-containing impurities naturally
found in crude oil are present in petroleum fractions.
(ii)
The pollutant gas NO is found in the exhaust gases from petrol engines. Explain why
NO is formed in petrol engines but is not readily formed when petrol burns in the
open air.
(iii)
The pollutant gas CO is also found in the exhaust gases from petrol engines. Explain
how CO and NO are removed from the exhaust gases and why the removal of each
of them is desirable.
(10)
(Total 17 marks)
Page 1 of 184
Q3.
(a) The equation below shows the reaction of 2-bromopropane with an excess of
ammonia.
CH3CHBrCH3 + 2NH3 → CH3CH(NH2)CH3 + NH4Br
Name and outline the mechanism involved.
Name of mechanism ….................................................................................
Mechanism
(5)
(b)
When 2-bromopropane is heated with ethanolic potassium hydroxide, an elimination
reaction occurs. State the role of potassium hydroxide and outline a mechanism for this
reaction.
Role of potassium hydroxide ........................................................................
Mechanism
(5)
(Total 10 marks)
Page 2 of 184
Q4.
Propene reacts with bromine by a mechanism known as electrophilic addition.
(a)
Explain what is meant by the term electrophile and by the term addition.
Electrophile ..................................................................................................
......................................................................................................................
Addition ........................................................................................................
......................................................................................................................
(2)
(b)
Explain why bromine, a non-polar molecule, is able to react with propene.
......................................................................................................................
......................................................................................................................
......................................................................................................................
(2)
(c)
Outline the mechanism for the electrophilic addition of bromine to propene. Give the name
of the product formed.
Mechanism
Name of product ...........................................................................................
(5)
(d)
The polymerisation of propene to form poly(propene) is an important industrial process.
Name the type of polymerisation involved.
......................................................................................................................
(1)
(Total 10 marks)
Page 3 of 184
Q5.
(a) In the manufacture of margarine, unsaturated vegetable oils such as sunflower oil are
hardened.
(i)
State the reagent and conditions used in this process.
Reagent ..............................................................................................
Conditions ...........................................................................................
.............................................................................................................
(ii)
Soft and hard margarines are obtained from the same vegetable oil. How does the
structure and the melting point of a soft margarine differ from that of a hard one?
Difference in structure .........................................................................
.............................................................................................................
Difference in melting point ...................................................................
.............................................................................................................
(5)
(b)
In the presence of reagent X, the alcohol shown below undergoes a reaction to form two
isomeric alkenes.
(i)
Name this alcohol.
.............................................................................................................
(ii)
Give the name of the type of reaction involved in the formation of the two alkenes.
.............................................................................................................
(iii)
Suggest the identity of reagent X.
.............................................................................................................
Page 4 of 184
(iv)
Give the structural formulae of the two isomeric alkenes.
Alkene 1
Alkene 2
(5)
(Total 10 marks)
Q6.
The equation below represents a reaction between methane and chlorine.
CH4(g) + Cl2(g) → CH3Cl(g) + HCl(g)
(a)
State an essential condition required for this reaction to occur. Explain why this condition is
essential.
Condition .....................................................................................................
Explanation ..................................................................................................
(2)
(b)
(i)
State the type of mechanism involved in the above reaction.
.............................................................................................................
(ii)
Name the three types of step involved in this mechanism.
Step 1 .................................................................................................
Step 2 .................................................................................................
Step 3 .................................................................................................
(4)
(c)
In addition to CH3Cl, compounds such as CH2Cl2 and CH3CH2Cl may also be formed when
chlorine reacts with methane.
(i)
Write equations for the two steps in the mechanism by which CH2Cl2 is formed from
CH3Cl
Equation 1 .........................................................................................
Equation 2 ..........................................................................................
Page 5 of 184
(ii)
Write an equation to represent a step in the mechanism in which CH3CH2Cl is
formed.
.............................................................................................................
(3)
(Total 9 marks)
Q7.
Reaction of 2-bromobutane with potassium hydroxide can produce two types of product
depending on the solvent used. In aqueous solution, the formation of an alcohol, E, is more likely
but in ethanolic solution the formation of alkenes is more likely.
(a)
For each type of product, name the type of reaction occurring and state the role of the
potassium hydroxide.
(4)
(b)
Name alcohol E and draw its structural formula. By reference to the structure of the
halogenoalkane, explain why the initial step in the mechanism of the reaction producing the
alcohol occurs.
(5)
(c)
When 2-bromobutane reacts with ethanolic potassium hydroxide, two structurally isomeric
alkenes are produced, one of which shows stereoisomerism.
Outline the mechanism for the formation of one of the structurally isomeric alkenes.
Explain why two structurally isomeric alkenes are formed and draw the structure of the
second structural isomer. Draw the structural formulae of the two stereoisomers.
(8)
(Total 17 marks)
Q8.
Epoxyethane is produced commercially by the oxidation of ethene.
State the reagent and the catalyst required for this process and identify two different types of
hazard associated with the production of epoxyethane. Write an equation for the reaction of
epoxyethane with water in a 1 : 1 mole ratio and give a use for the product obtained. Write an
equation for the reaction of an excess of epoxyethane with ethanol and give a use for the product
obtained.
(Total 8 marks)
Page 6 of 184
Q9.
(a) An alcohol containing carbon, hydrogen and oxygen only has 64.9% carbon and 13.5%
hydrogen by mass. Using these data, show that the empirical formula of the alcohol is
C4H10O
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
(3)
(b)
The structural formulae of two of the four possible alcohols of molecular formula C4H10O
are shown below.
(i)
What type of alcohol is Isomer 1? Suggest a reason why this type of alcohol is not
easily oxidised.
Type of alcohol ...................................................................................
Reason ...............................................................................................
(ii)
Draw the structural formulae of the two remaining alcohols of molecular formula
C4H10O
Isomer 3
Isomer 4
(4)
(c)
Isomer 2 was oxidised by adding it dropwise to acidified potassium dichromate(VI) solution
and immediately distilling off the product. When this product was treated with Fehling’s
solution, a red precipitate was formed.
(i)
State the type of product distilled off during the oxidation by acidified potassium
dichromate(VI) solution.
.............................................................................................................
(ii)
Write an equation for the oxidation by potassium dichromate(VI), showing clearly the
structure of the organic product. Use [O] to represent the oxidising agent.
.............................................................................................................
Page 7 of 184
(iii)
Name and draw a structure for the organic product formed by the reaction with
Fehling’s solution.
Name ..................................................................................................
Structure .............................................................................................
(5)
(d)
State one advantage and one disadvantage of the production of ethanol by the hydration
of ethene compared to the fermentation of glucose.
Advantage ...................................................................................................
Disadvantage ...............................................................................................
(2)
(e)
Outline a mechanism for the dehydration of ethanol to form ethene in the presence of an
acid catalyst.
(4)
(Total 18 marks)
Q10.
The reaction scheme below shows the conversion of compound A, 2-methylbut-1-ene, into
compound B and then into compound C.
(a)
The structure of A is shown below. Circle those carbon atoms which must lie in the same
plane.
(1)
Page 8 of 184
(b)
Outline a mechanism for the reaction in Step 1.
(4)
(c)
State the reagent and condition used in Step 2. Name compound C.
Reagent ......................................................................................................
Condition .....................................................................................................
Name of compound C ..................................................................................
(3)
(d)
When compound A is converted into compound C, a second alcohol, D, is also formed.
Alcohol D is isomeric with C but is formed as a minor product. Identify alcohol D and
explain why it is formed as the minor product.
Identity of alcohol D ......................................................................................
Explanation …...............................................................................................
......................................................................................................................
......................................................................................................................
(3)
(Total 11 marks)
Q11.
Many hydrocarbon compounds burn readily in air.
(i)
Write an equation to show the complete combustion of C15H32
......................................................................................................................
......................................................................................................................
(ii)
One of the gaseous products of the incomplete combustion of methane in gas fires is
known to be poisonous. Identify this product and write an equation for the reaction in which
it is formed from methane.
Identity of product ........................................................................................
Equation .......................................................................................................
(Total 4 marks)
Page 9 of 184
Q12.
In the presence of ultraviolet light, methane and chlorine react to form a number of chlorinecontaining products, including CH2Cl2 and CHCl3
(i)
Write an equation for the initiation step in the mechanism for this reaction.
......................................................................................................................
(ii)
Write the overall equation for the formation of CHCl3 from CH2Cl2 and Cl2
......................................................................................................................
(iii)
Write equations for the two propagation steps by which CH2Cl2 is converted into CHCl3
Equation 1 ...................................................................................................
Equation 2 ....................................................................................................
(iv)
Suggest what effect increasing the intensity of the ultraviolet light would have on the rate of
the reaction between methane and chlorine. Explain your answer.
Effect on rate ...............................................................................................
Explanation ..................................................................................................
(Total 6 marks)
Q13.
(a) Crude oil is separated into fractions by fractional distillation. Outline how different
fractions are obtained by this process.
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
(3)
Page 10 of 184
(b)
The table below gives details of the supply of, and demand for, some crude oil fractions.
Approximate %
Fractions
(i)
Typical supply
from crude oil
Global
demand
Gases
2
4
Petrol and naphtha
16
27
Kerosine
13
8
Gas oil
19
23
Fuel oil and bitumen
50
38
Use the data given above to explain why catalytic cracking of crude oil fractions is
commercially important.
.............................................................................................................
.............................................................................................................
.............................................................................................................
(ii)
Give the two main types of product obtained by catalytic cracking.
Type 1 .................................................................................................
Type 2 .................................................................................................
(4)
(c)
Name a catalyst used in catalytic cracking. State the type of mechanism involved and
outline the industrial conditions used in the process.
Catalyst .......................................................................................................
Type of mechanism/…................................................................................
Conditions ....................................................................................................
(4)
(Total 11 marks)
Q14.
(a)
(i)
Write an equation for the formation of epoxyethane from ethene, showing the
structure of the product.
Page 11 of 184
(ii)
Explain why the epoxyethane molecule is highly reactive.
.............................................................................................................
(iii)
Give the structure of the product formed by the reaction of one molecule of
epoxyethane with one molecule of water. Give one use for this product.
Structure
Use ..............................................................................................................
(5)
(b)
But-2-ene can exist in two isomeric forms. Give the structures of these two isomers and
name the type of isomerism.
Structure 1
Structure 2
Type of isomerism ................................................................................................
(3)
(Total 8 marks)
Q15.
(a) Ethanol can be manufactured by the direct hydration of ethene and by the
fermentation of sugars.
(i)
State what is meant by the term hydration.
.............................................................................................................
Page 12 of 184
(ii)
Give one advantage and one disadvantage of manufacturing ethanol by fermentation
rather than by hydration.
Do not include energy consumption or cost.
Advantage ...........................................................................................
.............................................................................................................
Disadvantage ......................................................................................
.............................................................................................................
(3)
(b)
Ethanol can be oxidised to an aldehyde and to a carboxylic acid.
(i)
Draw the structure of this aldehyde and of this carboxylic acid.
Structure of aldehyde
(ii)
Structure of carboxylic acid
Give a suitable reagent and reaction conditions for the oxidation of ethanol to form the
carboxylic acid as the major product.
Reagent ..............................................................................................
Conditions ...........................................................................................
.............................................................................................................
(5)
(c)
(i)
Draw the structure of an alcohol containing four carbon atoms which is resistant to
oxidation.
Page 13 of 184
(ii)
Draw the structure of an alcohol containing four carbon atoms which can be oxidised
to a ketone.
(2)
(d)
In the presence of a catalyst, ethanol can be dehydrated to ethene.
(i)
Give a suitable catalyst for use in this reaction.
.............................................................................................................
(ii)
Complete the mechanism for this dehydration reaction.
(5)
(Total 15 marks)
Page 14 of 184
Q16.
(a) Propene reacts with hydrogen bromide by an electrophilic addition mechanism
forming 2-bromopropane as the major product.
The equation for this reaction is shown below.
(i)
Outline the mechanism for this reaction, showing the structure of the intermediate
carbocation formed.
(ii)
Give the structure of the alternative carbocation which could be formed in the
reaction between propene and hydrogen bromide.
(5)
Page 15 of 184
(b)
A substitution reaction occurs when 2-bromopropane reacts with aqueous sodium
hydroxide.
(i)
Draw the structure of the organic product of this reaction and give its name.
Structure
Name ..................................................................................................
(ii)
Name and outline the mechanism for this reaction.
Name of mechanism ...........................................................................
Mechanism
(5)
(c)
Under different conditions, 2-bromopropane reacts with sodium hydroxide to produce
propene.
(i)
Name the mechanism for this reaction.
.............................................................................................................
(ii)
State the role of sodium hydroxide in this reaction.
.............................................................................................................
(2)
(Total 12 marks)
Page 16 of 184
Q17.
The alkanes form an homologous series of hydrocarbons. The first four straight-chain
alkanes are shown below.
(a)
methane
CH4
ethane
CH3CH3
propane
CH3CH2CH3
butane
CH3CH2CH2CH3
(i)
State what is meant by the term hydrocarbon.
.............................................................................................................
.............................................................................................................
(ii)
Give the general formula for the alkanes.
.............................................................................................................
(iii)
Give the molecular formula for hexane, the sixth member of the series.
.............................................................................................................
(3)
(b)
Each homologous series has its own general formula. State two other characteristics of
an homologous series.
......................................................................................................................
......................................................................................................................
......................................................................................................................
(2)
(c)
Branched-chain structural isomers are possible for alkanes which have more than three
carbon atoms.
(i)
State what is meant by the term structural isomers.
.............................................................................................................
.............................................................................................................
.............................................................................................................
Page 17 of 184
(ii)
Name the two isomers of hexane shown below.
Name …................................................................................................
Name ...................................................................................................
(iii)
Give the structures of two other branched-chain isomers of hexane.
Isomer 3
Isomer 4
(6)
(d)
A hydrocarbon, W, contains 92.3% carbon by mass. The relative molecular mass of
W is 78.0
(i)
Calculate the empirical formula of W.
.............................................................................................................
.............................................................................................................
.............................................................................................................
.............................................................................................................
Page 18 of 184
(ii)
Calculate the molecular formula of W.
.............................................................................................................
.............................................................................................................
(4)
(Total 15 marks)
Q18.
Ethene can be converted into a variety of useful products as illustrated below.
(a)
Name and give a use for compound X.
(2)
(b)
Give a reagent for each of Reactions 1, 2, 4 and 5.
(4)
(c)
Outline a mechanism for Reaction 3.
(4)
(d)
Ethanol can be manufactured from ethene as shown in Reaction 1 or by the fermentation
of sugars. Outline the essential conditions and give an equation for the fermentation
reaction. Compare the relative rates and the purity of the product obtained in each case by
these two manufacturing processes.
(5)
(Total 15 marks)
Page 19 of 184
Q19.
(a) One of the isomers in part (a) is resistant to oxidation by acidified potassium
dichromate(VI).
(i)
Identify this isomer.
.............................................................................................................
(ii)
This isomer can be dehydrated. Give a suitable dehydrating agent and write an
equation for this dehydration reaction.
Dehydrating agent................................................................................
Equation ..............................................................................................
(3)
(b)
(i)
Identify the isomer in part (a) which can be oxidised to a ketone. Give the structure of
the ketone formed.
Isomer .................................................................................................
Structure of the ketone
(ii)
Identify one of the isomers in part (a) which can be oxidised to an aldehyde. Give the
structure of the aldehyde formed.
Isomer .................................................................................................
Structure of the aldehyde
(iii)
Give a reagent that can be used in a test to distinguish between a ketone and an
aldehyde. State what you would observe in the test.
Reagent ..............................................................................................
Observation with ketone ......................................................................
.............................................................................................................
Observation with aldehyde ..................................................................
.............................................................................................................
(7)
Page 20 of 184
(c)
Butan-1-ol can be oxidised to form a carboxylic acid. Using [O] to represent the oxidising
agent, write an equation for this reaction and name the product.
Equation ......................................................................................................
Name of product ..........................................................................................
(2)
(Total 12 marks)
Q20.
Four isomers with the formula C4H9OH are given below.
Isomer
Name
CH3CH2CH2CH2OH
butan-1-ol
2-methylpropan-2-ol
(i)
Complete the naming of the isomers in the table above.
(ii)
Name the type of isomerism shown by these four isomers.
......................................................................................................................
(Total 3 marks)
Page 21 of 184
Q21.
(a) Compounds with double bonds between carbon atoms can exhibit geometrical
isomerism.
(i)
Draw structures for the two geometrical isomers of 1,2-dichloroethene.
Isomer 1
(ii)
Isomer 2
What feature of the double bond prevents isomer 1 from changing into isomer 2?
.............................................................................................................
(3)
(b)
When 2-chloropropane reacts with sodium hydroxide, two different reactions occur.
Each reaction produces a different organic product.
(i)
Outline a mechanism for Reaction 1 and state the role of the hydroxide ion in this
reaction.
Mechanism
Role of the hydroxide ion ....................................................................
Page 22 of 184
(ii)
Outline a mechanism for Reaction 2 and state the role of the hydroxide ion in this
reaction.
Mechanism
Role of the hydroxide ion ....................................................................
(7)
(Total 10 marks)
Q22.
When chlorine reacts with trichloromethane, tetrachloromethane, CCl4, is formed.
(a)
(i)
Write the overall equation for this reaction.
.............................................................................................................
(ii)
State one essential condition for this reaction.
.............................................................................................................
(2)
(b)
The mechanism for the chlorination of trichloromethane is free-radical substitution, which
proceeds by a series of steps. Write equations for the steps named below in this
chlorination.
Initiation step
......................................................................................................................
First propagation step
......................................................................................................................
Second propagation step
......................................................................................................................
A termination step
......................................................................................................................
(4)
(Total 6 marks)
Page 23 of 184
Q23.
(a)
Butane, C4H10, is a hydrocarbon which is used as a fuel.
(i)
Explain what is meant by the term hydrocarbon.
.............................................................................................................
.............................................................................................................
(ii)
Explain what is meant by the term fuel.
.............................................................................................................
.............................................................................................................
(iii)
Write an equation for the complete combustion of butane.
.............................................................................................................
(iv)
Write an equation for the incomplete combustion of butane to produce carbon
monoxide and water.
.............................................................................................................
(v)
Under what conditions would you expect incomplete combustion to occur?
.............................................................................................................
(5)
(b)
Three different carbocations are formed by breaking C – C bonds in separate molecules of
butane during catalytic cracking. One of these structures is shown below. Give the
structures of the other two carbocations.
Structure 1
Structure 2
Structure 3
(2)
(c)
Ethane can be cracked in the presence of a catalyst to produce ethene and hydrogen.
(i)
Write an equation for this reaction.
.............................................................................................................
(ii)
Give a suitable catalyst for this reaction.
.............................................................................................................
Page 24 of 184
(iii)
State one reason why cracking is important.
.............................................................................................................
.............................................................................................................
(3)
(Total 10 marks)
Q24.
The three compounds CH3CH2CH2CH2OH, (CH3)3COH and CH3CH2CH2CHO can be
distinguished by use of the following three reagents
1.
2.
3.
(a)
potassium dichromate(VI) acidified with dilute sulphuric acid
Tollens’ reagent
ethanoic acid, together with a small amount of concentrated sulphuric acid.
Identify which of these three organic compounds would reduce acidified potassium
dichromate(VI). Give the structures of the organic products formed. Write a half-equation
for the reduction of dichromate(VI) ions in acidic solution.
(6)
(b)
Identify which one of these three organic compounds would reduce Tollens’ reagent. Give
the structure of the organic product formed. Write a half-equation for the reduction of
Tollens’ reagent.
(3)
(c)
Identify which of these three organic compounds would react with ethanoic acid in the
presence of concentrated sulphuric acid. In each case, give the structure of the organic
product formed.
(4)
(d)
State the number of peaks in the proton n.m.r. spectra of CH3CH2CH2CH2OH and of (CH3)
COH. (Analysis of peak splitting is not required.)
3
(2)
(Total 15 marks)
Q25.
Ethene is an important starting point for the manufacture of plastics and pharmaceutical
chemicals. Most of the ethene used by industry is produced by the thermal cracking of ethane
obtained from North Sea gas (Reaction 1). It is also possible to make ethene either from
chloroethane (Reaction 2) or from ethanol (Reaction 3).
(a)
Give essential conditions and reagents for each of Reactions 2 and 3.
(4)
Page 25 of 184
(b)
Name and outline a mechanism for Reaction 2. Suggest a reason why chloroethane is
not chosen by industry as a starting material to make ethene commercially.
(5)
(c)
Name and outline a mechanism for Reaction 3. Suggest why this route to ethene may
become used more commonly in the future as supplies of North Sea gas begin to run out.
(6)
(Total 15 marks)
Q26.
(a)
Chloromethane can be made by the reaction of chlorine with methane.
(i)
Give one essential condition for this reaction.
.............................................................................................................
(ii)
Name the mechanism for this reaction.
.............................................................................................................
(iii)
Further substitution can occur during this reaction. Identify the main organic product
when a large excess of chlorine is used in this reaction.
.............................................................................................................
(3)
(b)
Ethanenitrile can be made by reacting chloromethane with potassium cyanide.
(i)
Write an equation for this reaction.
.............................................................................................................
(ii)
Name the mechanism for this reaction.
.............................................................................................................
(iii)
Explain, in terms of bond enthalpies, why bromomethane reacts faster than
chloromethane with potassium cyanide.
.............................................................................................................
.............................................................................................................
.............................................................................................................
(3)
(c)
Ethanenitrile can be hydrolysed to a carboxylic acid by heating it under reflux with a dilute
acid. Identify the carboxylic acid formed in this reaction.
......................................................................................................................
(1)
Page 26 of 184
(d)
Chloromethane can react with ammonia to produce a primary amine.
(i)
What feature of the chloromethane molecule makes it susceptible to attack by an
ammonia molecule?
.............................................................................................................
(ii)
Name the amine produced in this reaction.
.............................................................................................................
(iii)
Outline a mechanism for this reaction.
(6)
(Total 13 marks)
Q27.
The burning of fossil fuels can produce atmospheric pollutants.
(a)
The combustion of petrol in an internal combustion engine can lead to the formation of
carbon monoxide, CO, and nitrogen monoxide, NO.
(i)
Write an equation for the incomplete combustion of octane, C8H18, to produce CO
and water only.
.............................................................................................................
(ii)
State one essential condition for the formation of NO in an engine. Write an equation
for the reaction in which NO is formed.
Condition ............................................................................................
Equation ..............................................................................................
(3)
Page 27 of 184
(b)
All new petrol-engined cars must be fitted with a catalytic converter.
(i)
Name one of the metals used as a catalyst in a catalytic converter.
.............................................................................................................
(ii)
Write an equation to show how CO and NO react with each other in a catalytic
converter.
.............................................................................................................
(2)
(c)
State why sulphur dioxide gas is sometimes found in the exhaust gases of petrol-engined
cars. Give one adverse effect of sulphur dioxide on the environment.
Reason for SO2 in exhaust gases .................................................................
......................................................................................................................
Environmental effect of SO2 ..........................................................................
......................................................................................................................
(2)
(Total 7 marks)
Q28.
(a)
Crude oil is composed mainly of alkanes, which are saturated hydrocarbons.
(i)
State what is meant by the term hydrocarbon.
.............................................................................................................
(ii)
State what is meant by the term saturated, as applied to a hydrocarbon.
.............................................................................................................
(2)
Page 28 of 184
(b)
Crude oil can be separated into the fractions listed in the table below.
Name of fraction
Number of carbon atoms
LPG (liquefied petroleum gas)
1–4
Petrol (gasoline)
4 – 12
Naphtha
7 – 14
11 – 15
Gas oil (diesel)
15 – 19
Mineral oil (lubricating oil)
20 – 30
Fuel oil
30 – 40
(i)
Name the process used to obtain these fractions from crude oil.
.............................................................................................................
(ii)
Complete the table by naming the missing fraction.
(2)
(c)
Some of the naphtha fraction is thermally cracked to produce more useful products.
(i)
Give the molecular formula of an alkane with ten carbon atoms.
.............................................................................................................
(ii)
Write an equation to illustrate the thermal cracking of one molecule of tetradecane,
C14H30, in which the products are ethene and propene, in the ratio of 2:1, and one
other product.
.............................................................................................................
(iii)
Name the mechanism involved in thermal cracking.
.............................................................................................................
(4)
(Total 8 marks)
Q29.
Butenedioic acid, HOOCCH=CHCOOH, occurs as two stereoisomers. One of the isomers
readily forms the acid anhydride C4H2O3 when warmed.
(a)
Draw the structures of the two isomers of butenedioic acid and name the type of
isomerism shown.
Use the structures of the two isomeric acids to suggest why only one of them readily
forms an acid anhydride when warmed. Draw the structure of the acid anhydride formed.
(6)
Page 29 of 184
(b)
Identify one electrophile which will react with butenedioic acid and outline a mechanism
for this reaction.
(4)
(c)
Write an equation for a reaction which occurs when butenedioic acid is treated with an
excess of aqueous sodium hydroxide.
(2)
(d)
Describe and explain the appearance of the proton n.m.r. spectrum of butenedioic acid.
(3)
(Total 15 marks)
Q30.
(a)
Bromomethane, CH3Br, can be formed by a reaction between bromine and methane.
The mechanism for this reaction is similar to the mechanism for the chlorination
of methane.
(i)
Name the mechanism for this reaction.
.............................................................................................................
(ii)
Give the name of, and state an essential condition for, the first step in the
mechanism for this reaction.
Name ..................................................................................................
Essential condition ..............................................................................
(iii)
Write an equation for a termination step in the mechanism for this reaction which
gives ethane as a product.
.............................................................................................................
(iv)
Bromomethane can undergo further substitution. Write an overall equation for the
reaction between bromomethane and bromine in which dibromomethane is formed.
.............................................................................................................
(5)
Page 30 of 184
(b)
Bromomethane reacts with the nucleophile ammonia according to the following equation.
CH3Br + 2NH3 → CH3NH2 + NH4Br
(i)
Explain what is meant by the term nucleophile.
.............................................................................................................
.............................................................................................................
(ii)
Name the organic product of this reaction.
.............................................................................................................
(iii)
Outline a mechanism for this reaction.
(6)
(Total 11 marks)
Q31.
(a)
(i)
Give a suitable reagent and state the necessary conditions for the conversion of
propan-2-ol into propanone. Name the type of reaction.
Reagent ..............................................................................................
Conditions ...........................................................................................
Type of reaction ...................................................................................
(ii)
Propanone can be converted back into propan-2-ol. Give a suitable reagent and write
an equation for this reaction.
(Use [H] to represent the reagent in your equation.)
Reagent ...............................................................................................
Equation
.............................................................................................................
(5)
Page 31 of 184
(b)
Propanal is an isomer of propanone.
(i)
Draw the structure of propanal.
(ii)
A chemical test can be used to distinguish between separate samples of propanone
and propanal. Give a suitable reagent for the test and describe what you would
observe with propanone and with propanal.
Test reagent .........................................................................................
Observation with propanone ................................................................
Observation with propanone ................................................................
(4)
(Total 9 marks)
Q32.
Consider the following reaction scheme.
(a)
(i)
Name the mechanism for Reaction 1.
.............................................................................................................
(ii)
Explain why 1-bromopropane is only a minor product in Reaction 1.
.............................................................................................................
.............................................................................................................
.............................................................................................................
(3)
Page 32 of 184
(b)
Give a suitable reagent and state the essential conditions required for Reaction 3.
Reagent ........................................................................................................
Conditions .....................................................................................................
(2)
(c)
The reagent used for Reaction 3 can also be used to convert 2-bromopropane into
propene. State the different conditions needed for this reaction.
......................................................................................................................
(1)
(d)
Reaction 2 proceeds in two stages.
Stage 1
CH3CH=CH2 + H2SO4 → CH3CH(OSO2OH)CH3
Stage 2
CH3CH(OSO2OH)CH3 + H2O → CH3CH(OH)CH3 + H2SO4
(i)
Name the class of alcohols to which propan-2-ol belongs.
.............................................................................................................
(ii)
Outline a mechanism for Stage 1 of Reaction 2, using concentrated sulphuric acid.
(iii)
State the overall role of the sulphuric acid in Reaction 2.
.............................................................................................................
(6)
(Total 12 marks)
Page 33 of 184
Q33.
(a)
Ethanol, C2H5OH, can be made from glucose, C6H12O6
(i)
Write an equation to represent this reaction.
.............................................................................................................
(ii)
Give the name of this process for making ethanol.
.............................................................................................................
(2)
(b)
Ethanol can be used as a fuel in the internal combustion engine of a motor car.
(i)
Write an equation for the complete combustion of ethanol.
.............................................................................................................
(ii)
Identify a pollutant produced when ethanol is burned in a limited supply of air.
.............................................................................................................
(iii)
Nitrogen monoxide, NO, is a pollutant gas produced by motor cars. Write an
equation to represent a reaction occurring in the catalytic converter which decreases
the amount of this pollutant.
.............................................................................................................
(3)
Page 34 of 184
(c)
Ethene can be formed by the dehydration of ethanol using concentrated sulphuric acid.
Name and complete a mechanism for this reaction.
Name of mechanism …................................................................................
Mechanism
(5)
(d)
Epoxyethane is manufactured from ethene. Give a suitable catalyst for this manufacturing
process. Write an equation for the reaction, clearly showing the structure of epoxyethane.
Catalyst ........................................................................................................
Equation
......................................................................................................................
(3)
(Total 13 marks)
Q34.
(a) Addition reactions to both alkenes and carbonyl compounds can result in the
formation of isomeric compounds.
(i)
Choose an alkene with molecular formula C4H8 which reacts with HBr to form
two structural isomers. Give the structures of these two isomers and name the type
of structural isomerism shown.
Outline a mechanism for the formation of the major product.
Page 35 of 184
(ii)
Using HCN and a suitable carbonyl compound with molecular formula C3H6O, outline
a mechanism for an addition reaction in which two isomers are produced.
Give the structures of the two isomers formed and state the type of isomerism
shown.
(14)
(b)
Explain why ethanoyl chloride reacts readily with nucleophiles.
Write an equation for one nucleophilic addition–elimination reaction of ethanoyl chloride.
(A mechanism is not required.)
(4)
(Total 18 marks)
Q35.
Consider the following scheme of reactions for making ethane-1,2-diol from ethene by two
different routes.
(a)
Name compound X and name a mechanism for Reaction 1. Explain why ethene is able
to react with bromine in this reaction, given that bromine molecules are non-polar.
(4)
(b)
Name and outline a mechanism for Reaction 3. Explain why compound Y is susceptible
to attack by hydroxide ions.
(4)
(c)
Identify a reagent and a suitable catalyst for Reaction 4. Name compound Z and explain
why compound Z reacts readily with water in Reaction 5.
(4)
Page 36 of 184
(d)
Give a use for ethane-1,2-diol. For each route from ethene to ethane-1,2-diol, identify one
hazard.
(3)
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
(Total 15 marks)
Page 37 of 184
Q36.
Glucose can be used as a source of ethanol. Ethanol can be burned as a fuel or can be
converted into ethene.
C6H12O6 → CH3CH2OH → H2C=CH2
glucose
(a)
ethanol
ethene
Name the types of reaction illustrated by the two reactions above.
Glucose to ethanol .......................................................................................
Ethanol to ethene .........................................................................................
(2)
(b)
(i)
State what must be added to an aqueous solution of glucose so that ethanol is
formed.
.............................................................................................................
(ii)
Identify a suitable catalyst for the conversion of ethanol into ethene.
.............................................................................................................
(2)
(c)
(i)
State the class of alcohols to which ethanol belongs.
.............................................................................................................
(ii)
Give one advantage of using ethanol as a fuel compared with using a petroleum
fraction.
.............................................................................................................
(2)
(d)
Most of the ethene used by industry is produced when ethane is heated to 900°C in the
absence of air. Write an equation for this reaction.
......................................................................................................................
(1)
(e)
Name the type of polymerisation which occurs when ethene is converted into poly(ethene).
......................................................................................................................
(1)
(Total 8 marks)
Page 38 of 184
Q37.
(a)
Complete the mechanism below by drawing appropriate curly arrows.
(3)
(b)
Draw and name the geometrical isomers of pent-2-ene.
Isomer 1
Name ............................…....................
Isomer 2
Name .............…...........................
(2)
(c)
Pent-1-ene reacts with hydrogen bromide to produce 2-bromopentane as the major
product.
(i)
Outline the mechanism for this reaction.
(ii)
Identify the minor product formed in this reaction.
.............................................................................................................
Page 39 of 184
(iii)
Explain why 2-bromopentane is the major product of this reaction.
.............................................................................................................
.............................................................................................................
.............................................................................................................
(7)
(Total 12 marks)
Q38.
Consider the following reaction schemes involving two alcohols, A and B, which are
position isomers of each other.
CH3CH2CH2CH2OH → CH3CH2CH2CHO → CH3CH2CH2COOH
A
butanal
butanoic acid
CH3CH2CH(OH)CH3 → CH3CH2COCH3
B
(a)
C
State what is meant by the term position isomers.
......................................................................................................................
......................................................................................................................
......................................................................................................................
(2)
(b)
Name compound A and compound C.
Compound A ...............................................................................................
Compound C ................................................................................................
(2)
(c)
Each of the reactions shown in the schemes above is of the same type and uses the
same combination of reagents.
(i)
State the type of reaction.
.............................................................................................................
(ii)
Identify a suitable combination of reagents.
.............................................................................................................
(iii)
State how you would ensure that compound A is converted into butanoic acid
rather than into butanal.
.............................................................................................................
.............................................................................................................
Page 40 of 184
(iv)
Draw the structure of an isomer of compound A which does not react with this
combination of reagents.
(v)
Draw the structure of the carboxylic acid formed by the reaction of methanol with
this combination of reagents.
(6)
(d)
(i)
State a reagent which could be used to distinguish between butanal and
compound C.
.............................................................................................................
(ii)
Draw the structure of another aldehyde which is an isomer of butanal.
(2)
(Total 12 marks)
Q39.
The mechanism for the reaction of methane with fluorine is a free-radical substitution
similar to the chlorination of methane.
(a)
Outline the following steps in the mechanism for the reaction of methane with fluorine to
form fluoromethane, CH3F
Initiation step
......................................................................................................................
First propagation step
......................................................................................................................
Page 41 of 184
Second propagation step
......................................................................................................................
A termination step
......................................................................................................................
(4)
(b)
Write an overall equation for the reaction of fluorine with fluoromethane to form
tetrafluoromethane.
......................................................................................................................
(1)
(Total 5 marks)
Q40.
(a)
(i)
Name the process used to separate petroleum into fractions.
.............................................................................................................
(ii)
Give the molecular formula for an alkane with nine carbon atoms.
.............................................................................................................
.......................................................................…...............................
(iii)
Write an equation for the complete combustion of the alkane C11H24
.............................................................................................................
(iv)
Write an equation for the incomplete combustion of C11H24 to produce carbon
and water only.
.............................................................................................................
(4)
(b)
Alkenes can be produced by cracking the naphtha fraction obtained from petroleum.
(i)
Write an equation for the thermal cracking of one molecule of C10 H22 to give
one molecule of propene and one molecule of an alkane only.
.............................................................................................................
(ii)
Draw the structure of the chain isomer of but-1-ene.
(2)
Page 42 of 184
(c)
The alkanes and the alkenes are examples of homologous series of compounds.
One feature of an homologous series is the gradual change in physical properties
as the relative molecular mass increases. State two other general features of an
homologous series of compounds.
Feature 1 ......................................................................................................
......................................................................................................................
Feature 2 ......................................................................................................
......................................................................................................................
(2)
(Total 8 marks)
Q41.
Some alcohols can be oxidised to form aldehydes, which can then be oxidised further to
form carboxylic acids.
Some alcohols can be oxidised to form ketones, which resist further oxidation.
Other alcohols are resistant to oxidation.
(a)
Draw the structures of the two straight-chain isomeric alcohols with molecular formula,
C4H10O
(2)
(b)
Draw the structures of the oxidation products obtained when the two alcohols from part (a)
are oxidised separately by acidified potassium dichromate(VI). Write equations for any
reactions which occur, using [O] to represent the oxidising agent.
(6)
(c)
Draw the structure and give the name of the alcohol with molecular formula C4H10O which
is resistant to oxidation by acidified potassium dichromate(VI).
(2)
(Total 10 marks)
Q42.
Chlorination of ethane follows a free-radical substitution mechanism. This mechanism is
similar to that which occurs when methane is chlorinated. The overall equation for the reaction of
ethane to form chloroethane is given below.
C2H6 + Cl2
C2H5Cl + HCl
State the conditions and outline a mechanism for this reaction. Show how butane can be formed
in this reaction.
(Total 5 marks)
Page 43 of 184
Q43.
Many naturally-occurring organic compounds can be converted into other useful products.
(a)
Glucose, C6H12O6, can be fermented to make ethanol, which can then be dehydrated to
make the unsaturated compound, ethane.
(i)
Write an equation for the fermentation of glucose to form ethanol.
.............................................................................................................
(ii)
Identify a catalyst for the dehydration of ethanol to form ethene. Write an equation for
this reaction.
Catalyst ...............................................................................................
Equation ..............................................................................................
(3)
(b)
Vegetable oils, which contain unsaturated compounds, are used to make margarine.
Identify a catalyst and a reagent for converting a vegetable oil into margarine.
Catalyst .......................................................................................................
Reagent .......................................................................................................
(2)
(c)
Oleic acid can be obtained from vegetable oils. Oleic acid is an example of an unsaturated
compound.
CH3(CH2)7CH=CH(CH2)7COOH
oleic acid
(i)
Deduce the molecular formula and the empirical formula of oleic acid.
Molecular formula ...............................................................................
Empirical formula ................................................................................
(ii)
State what is meant by the term unsaturated.
.............................................................................................................
(iii)
Identify a reagent for a simple chemical test to show that oleic acid is unsaturated.
State what you would observe when oleic acid reacts with this reagent.
Reagent …...........................................................................................
Observation with oleic acid ……...........................................................
.............................................................................................................
(5)
(Total 10 marks)
Page 44 of 184
Q44.
Consider the following reaction in which an alkene is formed from a haloalkane.
(a)
Name the haloalkane used in this reaction.
......................................................................................................................
(1)
(b)
Name and outline a mechanism for this reaction.
Name of mechanism ....................................................................................
Mechanism
(4)
(c)
Another alkene, which is a structural isomer of but-2-ene, is also formed during this
reaction.
(i)
State what is meant by the term structural isomers.
.............................................................................................................
.............................................................................................................
Page 45 of 184
(ii)
Draw the structure of this other alkene.
(2)
(Total 7 marks)
Q45.
Consider the following scheme of reactions.
(a)
In Reaction 1, ethene undergoes electrophilic addition with hydrogen bromide.
(i)
State what is meant by the term electrophile.
.............................................................................................................
.............................................................................................................
Page 46 of 184
(ii)
Outline a mechanism for this reaction.
(5)
(b)
Epoxyethane is formed from ethene in Reaction 3.
(i)
Identify a reagent and a catalyst for this reaction.
Reagent ..............................................................................................
Catalyst ...............................................................................................
(ii)
Draw the structure of epoxyethane.
(iii)
Identify a reagent which will react with epoxyethane to form ethane-1,2-diol in
Reaction 4.
.............................................................................................................
(4)
Page 47 of 184
(c)
In Reactions 2 and 5, bromoethane undergoes nucleophilic substitution.
(i)
Identify a reagent for Reaction 2. Name the organic product, P.
Reagent for Reaction 2 ......................................................................
Name of product P ..............................................................................
(ii)
Identify a reagent for Reaction 5. Name the organic product, Q.
Reagent for Reaction 5 ......................................................................
Name of product Q ..............................................................................
(iii)
Outline a mechanism for Reaction 5.
(8)
(Total 17 marks)
Q46.
Petroleum is separated into fractions by fractional distillation.
The petrol fraction (C4 to C12) is burned in internal combustion engines and the naphtha
fraction (C7 to C14) is cracked.
(a)
Petroleum is separated into fractions when it is heated and the vapour mixture is passed
into a fractionating column.
(i)
Explain what is meant by the term fraction as applied to fractional distillation.
.............................................................................................................
.............................................................................................................
(ii)
State a property of the molecules in petroleum which allows the mixture to be
separated into fractions.
.............................................................................................................
.............................................................................................................
Page 48 of 184
(iii)
Describe the temperature gradient in the column.
.............................................................................................................
.............................................................................................................
(3)
(b)
The fractions from petroleum contain alkane hydrocarbons.
(i)
Write an equation for the incomplete combustion of the alkane C8H18 to produce
carbon monoxide and water only.
.............................................................................................................
(ii)
One isomer of C8H18 is 2,2,3-trimethylpentane. Draw the structure of this isomer.
(2)
(c)
State one economic reason for the cracking of petroleum fractions.
......................................................................................................................
(1)
(d)
(i)
Give the type of reactive intermediate formed during catalytic cracking.
.............................................................................................................
(ii)
Identify a catalyst used in catalytic cracking.
.............................................................................................................
(2)
(e)
(i)
Give the type of reactive intermediate formed during thermal cracking.
State how this reactive intermediate is formed.
Reactive intermediate ..........................................................................
How intermediate is formed .................................................................
.............................................................................................................
Page 49 of 184
(ii)
Identify the different type of hydrocarbon produced in a high percentage by the
thermal cracking of alkanes.
.............................................................................................................
(3)
(Total 11 marks)
Q47.
Glucose, C6H12O6, can be converted into ethanol. Ethanol can be used as a fuel or can be
converted into ethene by acid-catalysed dehydration. Most of the ethene used by industry is
formed by the thermal cracking of alkanes.
(a)
State four essential conditions for the conversion of glucose into ethanol. Name the
process and give an equation for the reaction which takes place. Write an equation for the
complete combustion of ethanol.
(7)
(b)
Explain what is meant by the term dehydration. Identify a catalyst which could be used in
the acid-catalysed dehydration of ethanol. Write an equation for the reaction which takes
place.
(3)
(c)
State what is meant by the term cracking. Describe what happens during the thermal
cracking of alkanes and name the type of reactive intermediate. Give an essential condition
for this process. Write an equation for the thermal cracking of butane to give ethene as
one of the products.
(5)
(Total 15 marks)
Q48.
(a) Name and outline a mechanism for the reaction of 2-bromo-2-methylpropane with
ethanolic potassium hydroxide to form the alkene 2-methylpropene, (CH3)2C=CH2
Name of mechanism ....................................................................................
Mechanism
(4)
Page 50 of 184
(b)
Two stereoisomers of but-2-ene are formed when 2-bromobutane reacts with ethanolic
potassium hydroxide.
(i)
Explain what is meant by the term stereoisomers.
.............................................................................................................
.............................................................................................................
(ii)
Draw the structures and give the names of the two stereoisomers of
but-2-ene.
Stereoisomer 1
Stereoisomer 2
Name ................................................. Name ................................................
(iii)
Name this type of stereoisomerism.
.............................................................................................................
(5)
(c)
When 2-bromo-2-methylpropane reacts with aqueous potassium hydroxide,
2-methylpropan-2-ol is formed as shown by the following equation.
State the role of the hydroxide ions in this reaction.
......................................................................................................................
(1)
(d)
Write an equation for the reaction that occurs when CH3CH2CH2CH2Br reacts with an
excess of ammonia. Name the organic product of this reaction.
Equation ......................................................................................................
Name of product ..........................................................................................
(3)
(Total 13 marks)
Page 51 of 184
Q49.
The table below gives some of the names and structures of isomers having the molecular
formula C4H9Br
Structure
Name
CH3CH2CH2CH2Br
2-bromo - 2-methypropane
1-bromo - 2-methypropane
2-methypropane
Complete the table.
(Total 2 marks)
Q50.
(a)
Dichloromethane, CH2Cl2, is one of the products formed when chloromethane, CH3Cl,
reacts with chlorine.
(i)
Name the type of mechanism involved in this reaction and write an equation for each
of the steps named below.
Name of type of mechanism ..............................................................
Initiation step
.............................................................................................................
First propagation step
.............................................................................................................
Second propagation step
.............................................................................................................
(ii)
Write an overall equation for the formation of dichloromethane from chloromethane.
.............................................................................................................
(5)
Page 52 of 184
(b)
A compound contains 10.1% carbon and 89.9% chlorine by mass. Calculate the molecular
formula of this compound, given that its relative molecular mass (M r) is 237.0
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
(3)
(c)
Suggest the formulae of two bromine-containing organic compounds formed when
dibromomethane, CH2Br2, reacts with bromine.
Compound 1 ................................................................................................
Compound 2 ................................................................................................
(2)
(Total 10 marks)
Q51.
Consider the following reaction scheme, which leads to the formation of two compounds
V and W.
(a)
Give a suitable catalyst for Reaction 1 and name compound V.
Catalyst .......................................................................................................
Name of compound V ..................................................................................
(2)
Page 53 of 184
(b)
Name and outline a mechanism for Reaction 2.
Name of mechanism ....................................................................................
Mechanism
(5)
(c)
In Reaction 4, compound W is distilled from the reaction mixture.
(i)
Name compound W and draw its structure.
Name ..................................................................................................
Structure
(ii)
Name the type of reaction shown by Reaction 4.
.............................................................................................................
(3)
(Total 10 marks)
Q52.
The fractions obtained from petroleum contain saturated hydrocarbons that belong to the
homologous series of alkanes.
(a)
Any homologous series can be represented by a general formula.
(i)
State two other characteristics of homologous series.
Characteristic 1 ...................................................................................
.............................................................................................................
Characteristic 2 ...................................................................................
.............................................................................................................
(ii)
Name the process which is used to obtain the fractions from petroleum.
.............................................................................................................
Page 54 of 184
(iii)
State what is meant by the term saturated, as applied to hydrocarbons.
.............................................................................................................
.............................................................................................................
(4)
(b)
Decane has the molecular formula C10H22
(i)
State what is meant by the term molecular formula.
.............................................................................................................
.............................................................................................................
(ii)
Give the molecular formula of the alkane which contains 14 carbon atoms.
.............................................................................................................
(iii)
Write an equation for the incomplete combustion of decane, C10H22, to produce
carbon and water only.
.............................................................................................................
(3)
(c)
When petrol is burned in an internal combustion engine, some nitrogen monoxide, NO,
is formed. This pollutant is removed from the exhaust gases by means of a reaction in a
catalytic converter.
(i)
Write an equation for the reaction between nitrogen and oxygen to form nitrogen
monoxide.
.............................................................................................................
(ii)
Identify a catalyst used in a catalytic converter.
.............................................................................................................
(iii)
Write an equation to show how nitrogen monoxide is removed from the exhaust
gases as they pass through a catalytic converter.
.............................................................................................................
(3)
(Total 10 marks)
Page 55 of 184
Q53.
There are seven isomeric carbonyl compounds with the molecular formula C5H10O.
The structures and names of some of these isomers are given below.
Structure
Name
pentanal
2-methybutanal
2, 2-dimethypropanal
pentan-2-one
(a)
(i)
Complete the table.
(ii)
Two other isomeric carbonyl compounds with the molecular formula C5H10O are not
shown in the table. One is an aldehyde and one is a ketone. Draw the structure of
each.
isomeric aldehyde
isomeric ketone
(4)
(b)
Pentanal, CH3CH2CH2CH2CHO, can be oxidised to a carboxylic acid.
(i)
Write an equation for this reaction. Use [O] to represent the oxidising agent.
.............................................................................................................
Page 56 of 184
(ii)
Name the carboxylic acid formed in this reaction.
.............................................................................................................
(2)
(c)
Pentanal can be formed by the oxidation of an alcohol.
(i)
Identify this alcohol.
.............................................................................................................
(ii)
State the class to which this alcohol belongs.
.............................................................................................................
(2)
(Total 8 marks)
Q54.
The reaction of bromine with ethane is similar to that of chlorine with ethane. Three steps in
the bromination of ethane are shown below.
(a)
(i)
2Br•
Step 1
Br2
Step 2
Br• + CH3CH3
CH3CH2• + HBr
Step 3
CH3CH2• + Br2
CH3CH2Br + Br•
Name this type of mechanism.
.............................................................................................................
(ii)
Suggest an essential condition for this reaction.
.............................................................................................................
(iii)
Steps 2 and 3 are of the same type. Name this type of step.
.............................................................................................................
(iv)
In this mechanism, another type of step occurs in which free-radicals combine.
Name this type of step. Write an equation to illustrate this step.
Type of step .......................................................................................
Equation..............................................................................................
(5)
(b)
Further substitution in the reaction of bromine with ethane produces a mixture of liquid
organic compounds.
(i)
Name a technique which could be used to separate the different compounds in this
mixture.
.............................................................................................................
Page 57 of 184
(ii)
Write an equation for the reaction between bromine and ethane which produces
hexabromoethane, C2Br6, by this substitution reaction.
.............................................................................................................
(2)
(c)
The compound 1,2-dibromo-1,1,2,2-tetrafluoroethane is used in some fire extinguishers.
Draw the structure of this compound.
(1)
(d)
Halothane is used as an anaesthetic and has the following structure.
(i)
Give the systematic name of halothane.
.............................................................................................................
(ii)
Calculate the M r of halothane.
.............................................................................................................
(iii)
Calculate the percentage by mass of fluorine in halothane.
.............................................................................................................
(3)
(Total 11 marks)
Q55.
(a)
Bromoethane, CH3CH2Br, reacts with sodium hydroxide in an elimination reaction to
form ethene.
(i)
Outline a mechanism for this elimination reaction.
Page 58 of 184
(ii)
Suggest one reason why this method for making ethene is not used in industry.
.............................................................................................................
.............................................................................................................
(4)
(b)
Ethene is used to make epoxyethane.
(i)
State why epoxyethane is very reactive.
.............................................................................................................
.............................................................................................................
(ii)
Identify the product formed when one molecule of epoxyethane reacts with one
molecule of water. Give a use for this product.
Product...............................................................................................
Use .....................................................................................................
(3)
(Total 7 marks)
Q56.
(a) In industry, ethanol is made from ethene in an acid-catalysed reaction. Name the type
of reaction. Write an equation and identify a suitable catalyst for this reaction.
Type of reaction...........................................................................................
Equation.......................................................................................................
Catalyst ........................................................................................................
(3)
(b)
Ethanol burns completely in a plentiful supply of air, but incomplete combustion occurs if
the air supply is limited.
(i)
Identify a solid pollutant produced by burning ethanol in a limited supply of air.
.............................................................................................................
(ii)
Write an equation for the incomplete combustion of ethanol to produce the solid
pollutant that you have identified in part (b)(i).
.............................................................................................................
(2)
(Total 5 marks)
Page 59 of 184
Q57.
(a) Alcohols can be classed as primary, secondary or tertiary. Draw possible structures
for a primary, a secondary and a tertiary alcohol which have the molecular formula C4H8O.
Which of the structures you have drawn cannot be oxidised by potassium dichromate in
acid solution?
(4)
(b)
Explain what is meant by the fingerprint region of an infra-red spectrum. State how it is
used to confirm the identity of organic molecules such as the primary, secondary and
tertiary alcohols of molecular formula C4H8O.
(2)
(c)
Each of the parts below concerns a different pair of isomers. Deduce one possible
structural formula for each of the species A to F. Use, where appropriate, the table of infrared absorption data given on the data sheet.
(i)
A and B have the molecular formula C3H8O. A has a broad absorption band at
3300 cm–1 in its infra-red spectrum, but B does not.
(ii)
C and D have the molecular formula C5H10. C has a weak absorption band at
1650 cm–1 in its infra-red spectrum, but D does not.
(iii)
E and F have the molecular formula C3H6O and both have strong absorption bands
at about 1700 cm–1 in their infra-red spectra. E reacts with Tollens’ reagent but F
does not.
(6)
(Total 12 marks)
Q58.
Organic reaction mechanisms help to develop an understanding of how and why reactions
occur.
(a)
Propene reacts with hydrogen bromide by an electrophilic addition mechanism forming 2bromopropane as the major product.
The equation for this reaction is shown below.
(i)
Outline the mechanism for this reaction, showing the structure of the intermediate
carbocation formed.
Page 60 of 184
(ii)
Give the structure of the alternative carbocation which could be formed in the
reaction between propene and hydrogen bromide.
(5)
(b)
A substitution reaction occurs when 2-bromopropane reacts with aqueous sodium
hydroxide.
(i)
Draw the structure of the organic product of this reaction and give its name.
Structure
Name ..................................................................................................
(ii)
Name and outline the mechanism for this reaction.
Name of mechanism ...........................................................................
Mechanism
(5)
(c)
Under different conditions, 2-bromopropane reacts with sodium hydroxide to produce
propene.
(i)
Name the mechanism for this reaction
.............................................................................................................
(ii)
State the role of sodium hydroxide in this reaction
.............................................................................................................
(2)
(Total 12 marks)
Page 61 of 184
Q59.
(a)
Hexane (C6H14) is a hydrocarbon which is a component of LPG (liquid petroleum gas),
used as a fuel for heating. When burning fuels in boilers it is important to ensure complete
combustion.
(i)
Give two reasons why boilers are designed to ensure complete combustion.
Reason 1 ............................................................................................
.............................................................................................................
Reason 2 ............................................................................................
.............................................................................................................
(ii)
Write an equation for the incomplete combustion of hexane.
.............................................................................................................
(iii)
Suggest how an engineer or a chemist could demonstrate that the combustion of
hexane in a faulty boiler was incomplete.
.............................................................................................................
(5)
(b)
Branched chain alkanes are often preferred as fuels. Draw the structure of two branched
chain isomers of hexane and name the first isomer.
Isomer 1
Isomer 2
Name of isomer 1 ........................................................................................
(3)
(c)
Hexane can be cracked in the presence of a catalyst to produce another hydrocarbon, Z,
and methane.
(i)
Draw a possible structure for Z.
Page 62 of 184
(ii)
Give a suitable catalyst for this reaction.
.............................................................................................................
(iii)
Suggest why the product Z has more commercial value than hexane.
.............................................................................................................
.............................................................................................................
(3)
(d)
The overall equation for the production of dichloromethane from methane and chlorine is
shown below.
CH4 + 2Cl2 → CH2Cl2 + 2HCl
(i)
Calculate the % atom economy for the formation of CH2Cl2 in this reaction.
.............................................................................................................
.............................................................................................................
.............................................................................................................
(ii)
Give one reason why this atom economy of less than 100% is an important
consideration for the commercial success of this process and predict how a
chemical company would maximise profits from this process.
.............................................................................................................
.............................................................................................................
.............................................................................................................
(3)
(Total 14 marks)
Page 63 of 184
Q60.
Petrol contains saturated hydrocarbons. Some of the molecules in petrol have the
molecular formula C8H18 and are referred to as octanes. These octanes can be obtained from
crude oil by fractional distillation and by cracking suitable heavier fractions.
Petrol burns completely in a plentiful supply of air but can undergo incomplete combustion in a
car engine.
(a)
State the meaning of both the words saturated and hydrocarbon as applied to the term
saturated hydrocarbon.
Name the homologous series to which C8H18 belongs.
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
(3)
(b)
Outline the essential features of the fractional distillation of crude oil that enable the crude
oil to be separated into fractions.
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
(4)
Page 64 of 184
(c)
C8H18 is obtained by the catalytic cracking of suitable heavy fractions.
State what is meant by the term cracking and name the catalyst used in catalytic cracking.
Write an equation to show how one molecule of C14H30 is cracked to form one molecule of
C8H18 and one molecule of another hydrocarbon.
Explain why oil companies need to crack ‘suitable heavy fractions’.
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
(4)
(d)
Write an equation for the incomplete combustion of C8H18 to form carbon monoxide and
water only.
A catalytic converter is used to remove carbon monoxide from the exhaust gases in a car.
Identify a catalyst used in the catalytic converter.
Write an equation to show how carbon monoxide is removed in a catalytic converter.
State why the water produced in the exhaust gases may contribute to global warming.
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
(4)
Page 65 of 184
(e)
When some petrol was accidentally contaminated in 2007, the sensors in the affected
cars caused a decrease in the supply of petrol to the engine.
Suggest the effect that the contaminated fuel would have on the performance of the cars.
State how the oil company might have recognised the problem before the petrol was sold.
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
(2)
(f)
The molecular formula C8H18 represents several structural isomers.
State what is meant by the term structural isomers.
Name the following structural isomer of C8H18
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
(3)
(Total 20 marks)
Page 66 of 184
Q61.
One of the first substances used as an anaesthetic in medicine was chloroform
(trichloromethane, CHCl3). By 1950, halothane was in common use but by 1990 this had been
replaced by more acceptable anaesthetics such as desflurane.
CF3CHBrCl
CF3CHFOCHF2
halothane
desflurane
One reason for replacing halothane was that it is an organic compound that contains chlorine.
Chlorine-containing organic compounds are thought to cause damage to the ozone layer in the
upper atmosphere.
(a)
Name and outline a mechanism for the reaction of chlorine with methane to form
chloromethane (CH3Cl).
Write an overall equation for the reaction of chlorine with methane to form
trichloromethane (CHCl3).
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
(5)
Page 67 of 184
(b)
Explain how chlorine atoms are formed from chlorine-containing organic compounds in the
upper atmosphere.
Explain, with the aid of equations, how chlorine atoms act as a catalyst in the
decomposition of ozone into oxygen.
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
(6)
(c)
Use the formulae of the two anaesthetics, halothane and desflurane, to help to explain why
desflurane is considered to be a more environmentally acceptable anaesthetic than
halothane.
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
(2)
(Total 13 marks)
Page 68 of 184
Q62.
Nucleophiles react with bromoethane in substitution reactions. This type of reaction is
illustrated in the following scheme.
(a)
State what is meant by the term nucleophile.
......................................................................................................................
(1)
(b)
Outline a mechanism for the reaction of potassium cyanide with bromoethane
(Reaction 1).
(2)
(c)
Explain why an excess of ammonia is needed in Reaction 2 to produce a high yield of
ethylamine.
......................................................................................................................
......................................................................................................................
(1)
Page 69 of 184
(d)
When potassium hydroxide reacts with bromoethane, ethene can also be formed.
Name and outline a mechanism for this reaction.
Name of mechanism ....................................................................................
Mechanism
(4)
(Total 8 marks)
Q63.
The reaction of bromine with an alkene is used in a test to show that the alkene is
unsaturated.
(a)
State what is meant by the term unsaturated as applied to an alkene.
......................................................................................................................
(1)
(b)
Name and outline a mechanism for the reaction of bromine with but-2-ene.
Name of mechanism ....................................................................................
Mechanism
(5)
(c)
But-2-ene can exist as a pair of stereoisomers.
(i)
State what is meant by the term stereoisomers.
.............................................................................................................
.............................................................................................................
.............................................................................................................
(2)
Page 70 of 184
(ii)
Draw the structure of (E)-but-2-ene.
.............................................................................................................
(1)
(Total 9 marks)
Q64.
Hexane is a member of the homologous series of alkanes.
(a)
State two characteristics of a homologous series.
Characteristic 1 ............................................................................................
......................................................................................................................
Characteristic 2 …….....................................................................................
......................................................................................................................
(2)
(b)
(i)
Hexane can be converted into 2,2-dichlorohexane.
Draw the displayed formula of 2,2-dichlorohexane and deduce its empirical formula.
Displayed formula
Empirical formula ................................................................................
.............................................................................................................
(2)
(ii)
Explain why 2,2-dichloro-3-methylpentane is a structural isomer of 2,2dichlorohexane.
.............................................................................................................
.............................................................................................................
(2)
Page 71 of 184
(c)
A reaction of hexane with chlorine is shown by the equation below.
C6H14 + 2Cl2 → C6H12Cl2 + 2HCl
Calculate the percentage atom economy for the formation of C6H12Cl2 in this reaction.
......................................................................................................................
......................................................................................................................
......................................................................................................................
(2)
(d)
The boiling points of some straight-chain alkanes are shown below.
Alkane
C4H10
C5H12
C6H14
Boiling point / °C
– 0.5
36.3
68.7
(i)
Explain the trend in these boiling points.
.............................................................................................................
.............................................................................................................
.............................................................................................................
(2)
(ii)
Name a process which can be used to separate C5H12 from C6H14
.............................................................................................................
(1)
(Total 11 marks)
Q65.
(a)
Two organic compounds with similar relative molecular masses are shown below.
Ethanol
(i)
Propane
State the type of bond present between the C and H atoms in both of these
molecules. Explain how this type of bond is formed.
Type of bond .......................................................................................
Explanation .........................................................................................
(2)
Page 72 of 184
(ii)
State the strongest type of intermolecular force present in each compound.
Liquid ethanol ......................................................................................
Liquid propane ….................................................................................
(2)
(b)
Ethanol dissolves in water. Draw a diagram to show how one molecule of ethanol interacts
with one molecule of water in the solution. Include partial charges and all lone pairs. The
ethanol molecule has been drawn for you.
(3)
(c)
Ethanol was the fuel used in the first mass-produced car, the Model T Ford.
(i)
Write an equation which shows how ethanol burns completely in air to form carbon
dioxide and water as the only products.
.............................................................................................................
(1)
(ii)
Suggest one environmental problem caused by incomplete combustion of ethanol in
a car engine.
.............................................................................................................
.............................................................................................................
(1)
(iii)
Suggest one economic problem for the car user caused by incomplete combustion
of ethanol in the car engine.
.............................................................................................................
.............................................................................................................
(1)
Page 73 of 184
(d)
Propane is also used as a fuel, although sometimes it can be contaminated with sulfurcontaining impurities. When this propane burns, these impurities form sulfur dioxide.
(i)
State how the sulfur dioxide can be removed from the waste gases produced when
this propane is burned on a large scale in industry. Suggest a reason why the
method you have stated may not be 100% efficient.
How removed .....................................................................................
.............................................................................................................
Reason for less than 100% efficiency .................................................
.............................................................................................................
(2)
(ii)
Although propane has a boiling point of –42 °C, it is usually supplied as a liquid for
use in camping stoves. Suggest why it is supplied as a liquid.
.............................................................................................................
.............................................................................................................
(1)
(Total 13 marks)
Q66.
Two isomeric ketones are shown below.
(a)
Name and outline a mechanism for the reaction of compound Q with HCN and name the
product formed.
Name of mechanism ……............................................................................
Mechanism
Name of product ..........................................................................................
(6)
Page 74 of 184
(b)
Some students were asked to suggest methods to distinguish between isomers Q and R.
One student suggested testing the optical activity of the products formed when Q and R
were reacted separately with HCN.
By considering the optical activity of these products formed from Q and R, explain why this
method would not distinguish between Q and R.
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
(3)
(c)
Other students suggested using mass spectrometry and the fragmentation patterns of the
molecular ions of the two isomers to distinguish between them.
They predicted that only one of the isomers would have a major peak at m/z = 57 in its
mass spectrum so that this method would distinguish between Q and R.
(i)
Identify the isomer that has a major peak at m/z = 57 in its mass spectrum.
.............................................................................................................
(1)
(ii)
Write an equation for the fragmentation of the molecular ion of this isomer to form the
species that produces the peak at m/z = 57.
.............................................................................................................
(2)
(iii)
Predict the m/z value of a major peak in the mass spectrum of the other isomer.
.............................................................................................................
(1)
(Total 13 marks)
Page 75 of 184
Q67.
There are four isomeric alcohols with the molecular formula C4H10O
(a)
Two of these are butan-l-ol (CH3CH2CH2CH2OH) and butan-2-ol.
The other two isomers are alcohol X and alcohol Y.
Draw the displayed formula for butan-2-ol.
Alcohol X does not react with acidified potassium dichromate(VI) solution.
Give the structure of alcohol X.
Name the fourth isomer, alcohol Y.
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
(3)
Page 76 of 184
(b)
The infrared spectrum of one of these isomeric alcohols is given below.
Identify one feature of the infrared spectrum which supports the fact that this is an alcohol.
You may find it helpful to refer to Table 1 on the Data Sheet.
Explain how infrared spectroscopy can be used to identify this isomeric alcohol.
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
(3)
(c)
British scientists have used bacteria to ferment glucose and produce the biofuel
butan-1-ol.
Write an equation for the fermentation of glucose (C6H12O6) to form butan-1-ol, carbon
dioxide and water only.
State one condition necessary to ensure the complete combustion of a fuel in air.
Write an equation for the complete combustion of butan-1-ol and state why it can be
described as a biofuel.
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
(4)
Page 77 of 184
(d)
Butan-1-ol reacts with acidified potassium dichromate(VI) solution to produce two organic
compounds.
State the class of alcohols to which butan-1-ol belongs.
Draw the displayed formula for both of the organic products.
State the type of reaction that occurs and the change in colour of the potassium
dichromate(VI) solution.
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
(5)
(Total 15 marks)
Q68.
(a)
Consider the following reaction.
(i)
Name and outline a mechanism for this reaction.
Name of mechanism ..........................................................................
Mechanism
(3)
(ii)
Name the haloalkane in this reaction.
.............................................................................................................
(1)
Page 78 of 184
(iii)
Identify the characteristic of the haloalkane molecule that enables it to undergo this
type of reaction.
.............................................................................................................
(1)
(b)
An alternative reaction can occur between this haloalkane and potassium hydroxide as
shown by the following equation.
Name and outline a mechanism for this reaction.
Name of mechanism ....................................................................................
Mechanism
(4)
(c)
Give one condition needed to favour the reaction shown in part (b) rather than that shown
in part (a).
......................................................................................................................
(1)
(d)
Alkenes can be polymerised to produce poly(alkenes).
(i)
State the type of polymerisation that alkenes undergo.
.............................................................................................................
(1)
(ii)
Name the alkene that gives a polymer with the repeating unit shown below.
Name of alkene ...................................................................................
(1)
(Total 12 marks)
Page 79 of 184
Q69.
Consider the following scheme of reactions.
(a)
State the type of structural isomerism shown by propanal and propanone.
......................................................................................................................
(1)
(b)
A chemical test can be used to distinguish between separate samples of propanal and
propanone.
Identify a suitable reagent for the test.
State what you would observe with propanal and with propanone.
Test reagent ................................................................................................
Observation with propanal ...........................................................................
Observation with propanone ........................................................................
(3)
(c)
State the structural feature of propanal and propanone which can be identified from their
infrared spectra by absorptions at approximately 1720 cm–1.
You may find it helpful to refer to Table 1 on the Data Sheet.
......................................................................................................................
(1)
(d)
The reaction of chlorine with propane is similar to the reaction of chlorine with methane.
(i)
Name the type of mechanism in the reaction of chlorine with methane.
.............................................................................................................
(1)
Page 80 of 184
(ii)
Write an equation for each of the following steps in the mechanism for the reaction of
chlorine with propane to form l-chloropropane (CH3CH2CH2Cl).
Initiation step
.............................................................................................................
First propagation step
.............................................................................................................
Second propagation step
.............................................................................................................
A termination step to form a molecule with the empirical formula C3H7
.............................................................................................................
(4)
(e)
High resolution mass spectrometry of a sample of propane indicated that it was
contaminated with traces of carbon dioxide.
Use the data in the table to show how precise M r values can be used to prove that the
sample contains both of these gases.
Atom
Precise relative atomic mass
12
C
12.00000
1
H
1.00794
16
O
15.99491
......................................................................................................................
......................................................................................................................
......................................................................................................................
(2)
(Total 12 marks)
Page 81 of 184
Q70.
Alkanes are saturated hydrocarbons which can be obtained from crude oil.
Pentane is an example of an alkane. A molecule of pentane contains five carbon atoms.
(a)
(i)
State the meaning of the term saturated and of the term hydrocarbon as applied to
alkanes.
Saturated ............................................................................................
.............................................................................................................
Hydrocarbon .......................................................................................
.............................................................................................................
(2)
(ii)
Give the general formula for the alkanes.
.............................................................................................................
(1)
(b)
Pentane burns completely in oxygen.
(i)
Write an equation for this reaction.
.............................................................................................................
(1)
(ii)
State how the products of this reaction may affect the environment.
.............................................................................................................
.............................................................................................................
(1)
(c)
Give the name of a solid pollutant which may form when pentane burns incompletely in air.
......................................................................................................................
(1)
(d)
One molecule of C9H20 can be cracked to form one molecule of pentane and one other
product.
(i)
Write an equation for this cracking reaction.
.............................................................................................................
(1)
(ii)
Suggest a type of compound that can be manufactured from the other product of this
cracking reaction.
.............................................................................................................
.............................................................................................................
(1)
Page 82 of 184
(iii)
State why a high temperature is needed for cracking reactions to occur.
.............................................................................................................
.............................................................................................................
(1)
(e)
Pentane can react to form the following haloalkane Q.
(i)
Name Q.
.............................................................................................................
(1)
(ii)
State the type of structural isomerism shown by Q and the haloalkane shown below.
.............................................................................................................
(1)
(Total 11 marks)
Page 83 of 184
Q71.
Glucose, produced during photosynthesis in green plants, is a renewable source from
which ethanol can be made. Ethanol is a liquid fuel used as a substitute for petrol.
The processes involved can be summarised as follows.
Process 1
Photosynthesis in green plants
6CO2 + 6H2O → C6H12O6 + 6O2
Process 2
Fermentation of glucose to form ethanol
Process 3
Complete combustion of ethanol
CH3CH2OH + 3O2 → 2CO2 + 3H2O
(a)
State three essential conditions for the fermentation of aqueous glucose in Process 2.
Write an equation for the reaction that takes place during this fermentation.
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
(4)
(b)
It has been claimed that there is no net carbon (greenhouse gas) emission to the
atmosphere when ethanol made by Process 2 is used as a fuel.
State the term that is used to describe fuels of this type.
Use the equations for Processes 1, 2 and 3 to show why it can be claimed that there is no
net emission of carbon-containing greenhouse gases.
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
(3)
Page 84 of 184
(c)
Use the information from the equation for Process 3 above and the mean bond enthalpies
from the table below to calculate a value for the enthalpy change for this process.
Mean bond
enthalpy / kJ mol–1
C–H
C–C
C–O
O–H
C=O
O=O
+412
+348
+360
+463
+743
+496
Give one reason why the value calculated from mean bond enthalpies is different from the
value given in a data book.
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
(4)
(d)
A student carried out a simple laboratory experiment to measure the enthalpy change for
Process 3. The student showed that the temperature of 200 g of water increased by 8.0 °
C when 0.46 g of pure ethanol was burned in air and the heat produced was used to warm
the water.
Use these results to calculate the value, in kJ mol–1, obtained by the student for this
enthalpy change. (The specific heat capacity of water is 4.18 J K–1 g–1)
Give one reason, other than heat loss, why the value obtained from the student’s results is
less exothermic than a data book value.
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
(4)
(Total 15 marks)
Page 85 of 184
Q72.
Chlorine is a useful industrial chemical.
(a)
Chlorine gas is used in the manufacture of chlorine-containing organic compounds.
(i)
Write equations for the following steps in the mechanism for the reaction of chlorine
with ethane to form chloroethane (CH3CH2Cl).
Initiation step
.............................................................................................................
First propagation step
.............................................................................................................
Second propagation step
.............................................................................................................
A termination step producing butane.
.............................................................................................................
(4)
(ii)
Give one essential condition and name the type of mechanism in this reaction of
chlorine with ethane.
Essential condition .............................................................................
Type of mechanism ............................................................................
(2)
(b)
Chlorine reacts with cold water.
(i)
Write an equation for this reaction.
.............................................................................................................
(1)
(ii)
Give one large-scale application of the use of chlorine in water. Explain why it is used
in this application even though chlorine is very toxic. Do not include cost.
Example of application….....................................................................
Explanation of use ..............................................................................
(2)
(iii)
Two different chlorine-containing compounds are formed when chlorine reacts with
cold, dilute sodium hydroxide solution. One of these compounds is sodium chloride.
Name the other chlorine-containing compound formed.
.............................................................................................................
(1)
(c)
Chlorine is used in the extraction of bromine from seawater.
(i)
Write the simplest ionic equation for the reaction of chlorine with bromide ions.
.............................................................................................................
(1)
Page 86 of 184
(ii)
Explain why bromine has a higher boiling point than chlorine.
.............................................................................................................
.............................................................................................................
.............................................................................................................
(2)
(Total 13 marks)
Q73.
The alkene (Z)-3-methylpent-2-ene reacts with hydrogen bromide as shown below.
(a)
(i)
Name the major product P.
.............................................................................................................
(1)
(ii)
Name the mechanism for these reactions.
.............................................................................................................
(1)
(iii)
Draw the displayed formula for the minor product Q and state the type of structural
isomerism shown by P and Q.
Displayed formula for Q
Type of structural isomerism ..............................................................
(2)
Page 87 of 184
(iv)
Draw the structure of the (E)-stereoisomer of 3-methylpent-2-ene.
(1)
(b)
The infrared spectra of two compounds R and S are shown below. R and S have the
molecular formula C6H12 and are structural isomers of 3-methylpent-2-ene. R is an
unsaturated hydrocarbon and S is a saturated hydrocarbon.
Spectrum 1
Spectrum 2
(i)
Identify the infrared Spectrum 1 or 2 that represents compound R.
Use information from the infrared spectra to give one reason for your answer.
You may find it helpful to refer to Table 1 on the Data Sheet.
R is represented by Spectrum ................
Reason ...............................................................................................
.............................................................................................................
(2)
Page 88 of 184
(ii)
State the type of structural isomerism shown by R and S.
.............................................................................................................
(1)
(iii)
Name one possible compound which could be S.
.............................................................................................................
(1)
(Total 9 marks)
Q74.
Sulfuric acid is an important chemical in many industrial and laboratory reactions.
Consider the following three reactions involving sulfuric acid.
Reaction 1
Mg(OH)2 + H2SO4 → MgSO4 + 2H2O
Reaction 2
The reaction of solid sodium bromide with concentrated
sulfuric acid
Reaction 3
H2C=CH2 + H2O
(a)
CH3CH2OH
Give a use for magnesium hydroxide in medicine.
......................................................................................................................
(1)
(b)
Sulfuric acid behaves as an oxidising agent in Reaction 2.
(i)
In terms of electrons, state the meaning of the term oxidising agent.
.............................................................................................................
(1)
(ii)
Give the formula of the oxidation product that is formed from sodium bromide in
Reaction 2.
.............................................................................................................
(1)
(iii)
Deduce the half-equation for the reduction of H2SO4 to SO2 in Reaction 2.
.............................................................................................................
(1)
Page 89 of 184
(c)
The formation of ethanol in Reaction 3 uses concentrated sulfuric acid and proceeds in
two stages according to the following equations.
Stage 1
H2C=CH2 + H2SO4 → CH3CH2OSO2OH
Stage 2
CH3CH2OSO2OH + H2O → CH3CH2OH + H2SO4
(i)
State the overall role of sulfuric acid in Reaction 3.
.............................................................................................................
(1)
(ii)
Outline a mechanism for Stage 1 of this reaction.
(4)
(iii)
State the class of alcohols to which ethanol belongs.
.............................................................................................................
(1)
(iv)
Draw the displayed formula of the carboxylic acid formed when ethanol is oxidised by
an excess of acidified potassium dichromate(VI) solution.
(1)
(Total 11 marks)
Page 90 of 184
Q75.
Sulfuric acid is an important chemical in many industrial and laboratory reactions.
Consider the following three reactions involving sulfuric acid.
Reaction 1
Mg(OH)2 + H2SO4 → MgSO4 + 2H2O
Reaction 2
The reaction of solid sodium bromide with concentrated
sulfuric acid
Reaction 3
H2C=CH2 + H2O
(a)
CH3CH2OH
Give a use for magnesium hydroxide in medicine.
......................................................................................................................
(1)
(b)
Sulfuric acid behaves as an oxidising agent in Reaction 2.
(i)
In terms of electrons, state the meaning of the term oxidising agent.
.............................................................................................................
(1)
(ii)
Give the formula of the oxidation product that is formed from sodium bromide in
Reaction 2.
.............................................................................................................
(1)
(iii)
Deduce the half-equation for the reduction of H2SO4 to SO2 in Reaction 2.
.............................................................................................................
(1)
(c)
The formation of ethanol in Reaction 3 uses concentrated sulfuric acid and proceeds in
two stages according to the following equations.
Stage 1
H2C=CH2 + H2SO4 → CH3CH2OSO2OH
Stage 2
CH3CH2OSO2OH + H2O → CH3CH2OH + H2SO4
(i)
State the overall role of sulfuric acid in Reaction 3.
.............................................................................................................
(1)
Page 91 of 184
(ii)
Outline a mechanism for Stage 1 of this reaction.
(4)
(iii)
State the class of alcohols to which ethanol belongs.
.............................................................................................................
(1)
(iv)
Draw the displayed formula of the carboxylic acid formed when ethanol is oxidised by
an excess of acidified potassium dichromate(VI) solution.
(1)
(Total 11 marks)
Page 92 of 184
M1.
Condition = two from yeast (anywhere in question)
Air excluded or sterile / clean (2)
Ignore references to pressure / temperature / aqueous / dark / high
alcohol conc
Temperature too low inactivates / deactivates enzymes or reaction too slow (1)
Temperature too high destroys or denatures yeast / enzymes (1)
Not kills enzymes; not deactivates here
Advantage 1 = sugar / glucose / carbohydrate is renewable resource / source (1)
Advantage 2 = production uses low level technology / cheap equipment (1)
Ignore references to energy
Do not allow contra-arguments about ethene
C6H12O6 → 2CH3CH2OH + 2CO2 balanced (1)
C2H5OH +3O2 → 2CO2 +3H2O balanced (1)
Allow C2H6O but penalise C2H5HO once
[8]
M2.
(a) Missing fraction = naphtha (allow naphtha from list if not quoted
separately) (1) Order = mineral oil (lubricating oil), gas oil (diesel),
kerosene (paraffin),
naphtha, petrol (gasoline) (1)
Mark order consequential on M1 (if no missing fraction
given, M2 = 0) Accept correct reversed order
Negative temperature gradient on the column
or temperature of column decreases upwards (1)
Larger molecules or heavier fractions condense at higher
temperatures or lower down the column or reference to
different boiling points
(ignore mp) (1)
4
(b)
Type of mechanism = (free) radical / homolytic
fission - used in complete sentence/phrase (1)
C21H44 → 3 C2H4 + 2 C3H6 + C9H20 correct alkenes (1)
Accept CH2CH2 & CH2CHCH3 all correct (1)
3
(c)
(i)
Sulphur (containing impurities) burn to form or forms SO2 or
oxides of sulphur (if oxide identified, must be correct) (1)
OR equation: e.g. S + O2 → SO2 or H2S + 1½O2 → SO2 + H2O
Leading to acid rain (must have specified oxides of S or burning)
or toxic product or respiratory problems (1)
Page 93 of 184
(ii)
NO formed by reaction between N2 and O2 from the air (1)
OR N2 +O2 → 2NO
High combustion temperature or spark in engine (1)
provides EA or sufficient heat / energy to break N N (1)
(iii)
Need to remove NO as forms acid rain or toxic product or causes
respiratory problems (1)
2NO + O2 → 2NO2 (1)
4NO2 + O2 + 2H2O → 4HNO3 (1)
Need to remove CO as it is poisonous (1)
Catalytic converter (1)
uses Pt / Rh / Pd / Ir (wrong answer cancels a correct one) (1)
Provides active sites / reduces EA (1)
Forms N2 + CO2 (1)
2NO + 2CO → N2 + 2CO2 (correct equation worth last 2 marks) (1)
Max 10
[17]
M3.
(a) Name of mechanism: nucleophilic substitution (1)
Mechanism:
Marks SN1 using same points
M2 requires
5
Page 94 of 184
(b)
Role of potassium hydroxide: Base (1)
Mechanism:
5
[10]
(a) Electrophile: e– pair / lone pair acceptor or e– deficient species or e–
seeking species (1)
For ‘species’ accept atom, molecule, ion
NOT ‘+’ ion
NOT ‘attracted to ‘-’ charge’
M4.
Addition: reaction which increases number of substituents or
convert double bond to single bond or where two molecules
form one molecule (1)
2
(b)
(High) e– dense or e– rich C=C or e– rich π bond or 4 e– between the C’s (1)
NOT just ‘C=C’
causes induced dipole in Br2 (1)
Ignore refs to ‘temporary’
can score M2 from δ+ / δ– on Br2 in (c) unless a contradicting error
in (b)
2
Page 95 of 184
(c)
Mechanism:
If incorrect alkene, lose M3 (wrong cation)
Mark M4 conseq on M3
Name of product: 1,2-dibromopropane (1)
5
(d)
addition (1)
Not additional
1
[10]
M5.
(a)
(i)
Reagent: Hydrogen of H2 (1)
Conditions: Ni (catalyst) (Ignore Pt) (1)
100 – 200 °C or heat (1)
Not ‘high temp’ or ‘warm’
M1 = 0, M2 = 1 then M3 = 0 max
or M1 = M2 = 0 then M3 = 0
M3 tied to M1. Only award M3 if M1 earned
(ii)
Difference in structure: soft margarine less hydrogenated or
has more C=C bonds or is more unsaturated than hard
margarine (1)
Difference in melting point: soft has lower melting point (1)
Must be comparison
5
(b)
(i)
3-methylbutan-2-ol (1)
No alternatives
(ii)
elimination or dehydration (1)
(iii)
(c) H2SO4 or (c) H3PO4 – name or correct formula (1)
Page 96 of 184
(iv)
Double bond must be shown
Accept any correct unambiguous structures
if but- 1-ene and but-2-ene offered, allow M2
5
[10]
M6.
(a) Condition: U.V. light or sunlight or 450°C or high temp (1)
Explanation: U.V. light etc. provides energy to break(Cl-Cl) bond (1)
Do not accept reference to Ea or wrong bond or ‘to make Cl
radicals’
2
(b)
(i)
(Free) radical substitution (1)
(ii)
Step 1: initiation (1)
Step 2: propagation (1)
Step 3: termination (1)
Any order
Don’t be too harsh on spelling
4
(c)
(i)
Equation 1: CH3 + Cl• → CH2Cl• + HCl (1)
Equation 2: CH2Cl• + Cl2 → CH2Cl2 + Cl• (1)
or CH2Cl• + Cl• → CH2Cl2
Mark equ independently
any order
(ii)
CH2Cl• + CH3• → CH3CH2Cl (1)
or CH3CH2• + Cl2 → CH3CH2Cl + Cl•
or CH3CH2• + Cl•→ CH3CH2Cl
Equ must have CH3CH2Cl as product
Accept C2H5Cl
Penalise absence of • once only
3
[9]
Page 97 of 184
M7.
(a)
Alcohol: Reaction = Substitution (/ hydrolysis) (1)
Ignore reference to nucleophilic, but electrophilic give zero
Alcohol: Role = nucleophile (/ lone pair donor) (1)
Alkene: reaction = elimination (1)
Ignore ref to nucleophilic or electrophilic
Alkene: base (/ proton acceptor) (1)
If no indication of order in (a) assume as in question.
If order is wrong can still score 'role' mark.
4
(b)
Alcohol: Role = butan-2-ol (1)
Not 2-hydroxybutane or but-2-ol
Appropriate structure for CH3CH(OH) CH2CH3 (1)
Brackets not essential
SN2 version
–
bond is polar
SN1 version
C–Br bond is polar (1)
Lone pair of OH–
C–Br bond breaks (1)
Attacks the Cδ+
forming carbocation / carbonium ion (1)
M1 can be scored from a diagram, M2 and M3 from written
explanation only
5
(c)
If but-2-ene not given here it may be obtained from cis / trans
isomer
H lost from different carbon atoms (1)
H removes from C1 and C3 to give two isomers (1)
Draws clear Cis and trans isomers for but-2-ene
Can score these marks from a diagram
8
[17]
Page 98 of 184
M8.
Oxygen or air (1) Can score from the equation
Silver catalyst (1)
Linked to process: e.g. Consequence of leaks etc. (1)
Hazard 1 = flammable or explosive (1)
Hazard 2: = toxic or causes respiratory failure or neurological effects (1)
(CH2CH2)O +H2O → HOCH2CH2OH (1) Not (CH2CH2)2O, CH2CH2O,
C2H4O, but only penalise once
Uses include antifreeze or polyester formation / terylene (1), Not plastics,
polymers, surfactants
n(CH2CH2)O + CH3CH2OH → CH3CH2O(CH2CH2O)nH (1)
Uses include brake fluids or plasticisers (1) OR surfactant or detergent
CH3CH2(OCH2CH2)nOH and H(CH2CH2O)n+1OH are OK in
last equation
[8]
M9.
(a)
% O = 21.6 % (1)
If % O not calculated only M2 available
C
H
= 5.41
= 13.5
Ratio: 4 : 10: 1
(
O
(1)
= 1.35
C4H10O) (1)
If arithmetic error in any result lose M3
If percentage composition calculation done zero
3
(b)
(i)
Type of alcohol: Tertiary (1)
Reason: No hydrogen atom on central carbon (1)
(ii)
Penalise missing bonds / incorrect bonds once per paper
4
(c)
(i)
Aldehyde (1)
Ignore named aldehydes or their structures,
penalise wrong named compound
Page 99 of 184
(ii)
CH3CH2CH2CH2OH + [O] → CH3CH2CH2CHO + H2O (1)
Balanced (1)
C4H10O is OK as a reactant
[O] can be over arrow
C3H7CHO not accepted for product, but C2H5CH2CHO is OK
If use C3 or C5 compounds no marks in (ii) C.E of wrong alcohol
(iii)
Name Butanoic acid (1)
Structure: CH3CH2CH2COOH (1)
mark conseq. or as stated
5
(d)
Advantage: Fast reaction OR pure product OR continuous process
OR cheap on manpower OR high yield, 100% alcohol (1)
Disadvantage: High technology OR ethene from non renewable source
OR expensive equipment not just costly (1)
Not answers based on fermentation
2
(e)
4
[18]
(a)
M10.
May circle 4 C’s separately
1
Page 100 of 184
(b)
Ignore δ+ and δ- unless wrong
4
(c)
Reagent: H2O or water OR steam, Or dilute sulphuric acid (1)
Condition: heat, or warm, or boil or reflux [50-100°C] (1)
Name of compound C: 2-methylbutan-2-ol (1)
Allow 2-methylbutane-2-ol
Penalise hydroxy-2-methylbutane and 2-methylbut-2-ol once only
in the paper
3
(d)
Identity of alcohol D: 2-methylbutan-1-ol (1),
OR its structure, could describe
structure
Explanation: C formed via t-carbocation; D via p-carbocation, (1)
tertiary more stable than primary (1)
If have wrong carbocation can still score stability mark
3
[11]
M11.
(i)
C15H32 + 23 O2 → 15 CO2 +16 H2O
Products (1)
Balance (1)
If wrong reactant C.E
(ii)
Identity of product: CO or carbon monoxide (1)
Equation: CH4 +
O2 → CO +2 H2O (1)
Any balanced equation using CH4, producing CO
could also make C + CO2
[4]
Page 101 of 184
M12.
Penalise missing • once only
(i)
Cl2 → 2 Cl• (1)
(ii)
CH2Cl2 + Cl2 → CHCl3 +HCl (1)
(iii)
CH2Cl2 + Cl• → CHCl2• +HCl (1)
CHCl2• +Cl2 → CHCl3 + Cl• (1)
Can reverse order
(iv)
Effect on rate: increases (1) If decrease given C.E zero marks
Explanation: more Cl• radicals formed (1)
More Cl atoms, more Cl—Cl or Cl2 bonds broken, more Cl2 have
EA, increased rate of Cl• production
[6]
M13.
(a) Crude oil is heated to vaporise it / oil vaporised (1)
(Vapour passed into fractionating) tower / column (1)
Top of tower cooler than bottom
or negative temperature gradient (1)
fractions separated by b.p
OR condensed at different temperatures OR levels
OR low boiling fractions at the top
OR at the top small molecules or light components (1)
max 3
(b)
(i)
Identify shortfall in supply - e.g. petrol / small molecules (1)
Higher value products OR more useful products (1)
OR cracking produces more of material (problem solving)
(ii)
Motor fuels
Aromatic hydrocarbons
Branched alkanes / hydrocarbons
Cycloalkanes
Any two (2)
Ignore specific fractions, alkanes, shorter alkanes, penalise
alkenes, and hydrogen
4
(c)
Catalyst: Zeolite / aluminosilicate (1)
Type of mechanism: Carbocation / heterolytic fission (1)
Conditions: High temp OR around 450 °C [300 – 600] °C NOT heat / warm (1)
Slight pressure [> 1 atm 10 atm OR 1 megaPa, 1000 kPa] (1)
NOT high pressure
4
[11]
Page 102 of 184
(a)
M14.
(i)
H C=CH + ½O →
2
2
2
(OR 2×)
Product (1) M1
Correct balanced equation (1) M2
OR C2H4
OR CH2=CH2
OR CH2CH2
NOT [O]
For M2, allow credit when C2H4O OR CH2CH2O are used
(ii)
strained (ring) (1)
NOT weak bonds
NOT unstable
Credit "stressed"
(iii)
Structure:
(1)
Use: antifreeze (1)
or production of Terylene
or feedstock for polyester or PET
NOT plasticiser
NOT solvent
NOT de-icer
NOT alcohol
5
(b)
Credit 1 mark for a correct formula for but-2-ene
Credit 1 mark for any pair of cis / trans isomers
Geometric(al)
Or cis-trans
Or diastereoisomerism
NOT stereoisomerism
3
[8]
M15.
(a)
(i)
addition of water / steam (1)
Ignore “to the reaction”
Page 103 of 184
(ii)
Advantage:
low technology
renewable feedstock / resource
allowed for use in drinks, perfumes
considered to be green (1)
any one
NOT “infinite” or “non-finite” resource
Disadvantage:
slow
low yield
significant land use
has to be distilled
labour intensive
any one
Ignore yeast
NOT (unqualified) batch production
NOT impure product
3
(b)
(i)
Structure of aldehyde
Structure of carboxylic acid
(1)
(1)
NOT CH3CHO
NOT CH3COOH
Penalise incorrect R group once
(ii)
Reagent: sodium (/ potassium) dichromate (VI)
(VI not essential) (1) M1
Conditions: acidified or sulphuric acid (1) Can be with reagent M2
(heat under reflux) (1) M3
Or correct formula for M1 and M2
M2 depends on M1 (but M2 correct from Cr2O72–, K2Cr2O72– etc
M3 mark independent
Credit KMnO4 for M1
Ignore T and P for M2
5
(c)
(i)
(ii)
(1)
(1)
2
(d)
(i)
Al2O3 or H2SO4 or H3PO4 (1)
Name or formula
Page 104 of 184
(ii)
For M1 the + can be on O or H if -OH2 used
For M2 the arrow must go to the + or to oxygen
Synchronous loss without carbocation loses carbocation
structure mark; can still score ¾ i.e. penalise M3
5
[15]
M16.
(a)
(i)
If wrong carbocation, lose structure mark
If wrong alkene, lose structure mark
Can still score ¾ i.e. penalise M3
Penalise M2 if
polarity included incorrectly
no bond between H and Br
bond is shown as
or
(ii)
credit secondary carbocation here if primary carbocation has been
used in (i)
Ignore attack on this carbocation by
5
Page 105 of 184
(b)
(i)
Structure:
No credit for propan-1-ol even when named correctly
Credit propane-2-ol
Name: propan-2-ol (1)
Not 2-hydroxypropane
(ii)
Name of mechanism: nucleophilic substitution (1) (both words)
(NOT SN1 orSN2)
Mechanism:
penalise incorrect polarity on C-Br (M1)
Credit the arrows even if incorrect haloalkane
If SN1, both marks possible
5
(c)
(i)
elimination (1)
Ignore nucleophylic elimination
Penalise electrophilic elimination
(ii)
base (1)
OR proton acceptor
NOT nucleophile (base)
2
[12]
M17.
(a)
(i)
Molecule/compound/consists/composed/made up of hydrogen and
carbon only (1)
(ii)
CnH2n+2 (1)
(iii)
C6H14 only (1)
Do not credit structures alone or in addition.
3
Page 106 of 184
(b)
Chemically similar / react in same way / same chemistry
Differ by CH2
gradation in physical properties OR specified trend e.g. b.p.
same functional group
Any 2, 2 marks 1 + 1
Not same molecular formula
2
(c)
(i)
Same molecular formula (1)
NOT same Mr
different structural formula / structures (1)
(or atoms arranged in different way)
NOT different spatial arrangements
Only credit M2 if M1 correct
(ii)
2-methylpentane (1)
2,2-dimethylbutane (1)
(iii)
OR correct condensed / structural formula
Penalise “sticks” once
Penalise absence of vertical bonds once
penalise badly drawn bonds once (vertical between H atoms)
6
(d)
(i)
M1 % by mass of H = 7.7(0)% (1)
M2
mol H = 7.70 / 1 = 7.70
mol C = 92.3 / 12 = 7.69 (1)
M3 (ratio 1:1
) CH
Credit variations for M2 e.g. 78 ×
and
=6
=6
Correct answer = 3 marks
(ii)
(CH has empirical mass of 13 and
=6
) C6H6 (1)
Correct answer 1 mark
4
[15]
Page 107 of 184
M18.
(a) ethan(e)-1,2-diol OR 1,2-ethan(e)diol (1)
antifreeze (1) OR production of Terylene / polyester
feedstock for polyester / PET
NOT surfactant NOT plasticizer NOT solvent NOT de-icer
2
(b)
Reaction 1
H2O or steam (1)
Reaction 2
O2 (1) NOT air
Ignore reaction 3
Reaction 4
H2O (1)
Reaction 5
NH3 (1)
For Reaction 4; credit dil H2SO4 OR H2SO4(aq) OR HCl (aq) but
NOT steam and NOT NaOH(aq)
4
(c)
Penalise M2 incorrect δ+ / δ–
Penalise δ– on alkene (M1)
Penalise dots on bonds once
Penalise M4 (structure) for use of wrong alkene
Penalise M1 for use of Br2
4
(d)
Water OR aqueous solution OR (aq) in equation (1)
M1
Yeast OR enzyme/zymase OR T 45°C
but T not below 20°C and allow warm
N.B. yeast and T=60°
con
Ignore pH
Ignore anaerobic / oxygen
Ignore time
Ignore pressure
M2
C6H12O6 → 2C2H5OH (or CH3CH2OH) + 2CO2
Allow C12H22O11 if balanced equation
M4 OR M5 needs the use of good English and correct chemistry
to gain credit
M3
Page 108 of 184
M4:
The rate of fermentation is slower (1)
OR The rate of hydration is faster
QoL OR (The rate of) fermentation is slow and
(the rate of) hydration is fast
reference correctly to time rather than rate gains credit
M5:
OR
OR
OR
OR
The product of fermentation is less pure or lower purity
The product of hydration is more pure or higher purity
The product of fermentation is impure and that of
hydration is pure
Specific reference to 10–15% versus 90–100%
correct reference to higher or lower yield
5
[15]
M19.
(a)
(i)
2-methylpropan-2-ol (1) OR the second one
(ii)
Dehydrating agent:
(1)
Equation:
Allow C4H9OH in equation provided RHS is correct
if b(i) is blank, b(ii) equation must be full for credit
i.e. NOT C4H9OH
Mark consequential on b(i)
3
(b)
(i)
Isomer: butan-2-ol OR the fourth one
[look at name in table]
wrong isomer = CE
Structure of the ketone:
(ii)
Isomer: butan-1-ol OR the first one
OR 2-methylpropan-1-ol OR the third one
[look at name in table]
Wrong isomer = CE
Structure of the aldehyde:
Either
Page 109 of 184
(iii)
Reagent
M1
Tollen’s
(AgNO3/NH3)
Fehling’s
Observation with ketone
M2
Stays colourless
no change
stays blue
no change
Observation with aldehyde
M3
Silver mirror
black ppt
red solid
orange/red
brown/ red
ppt/solid
Other include(*)
K2Cr2O7 / H2SO4
KMnO4/H2SO4
Schiff’s
Benedict’s
Wrong reagent R
No reagent = CE
Penalise AgNO3 [Ag(NH3)2] but allow M2 and M3 sequentially.
(*)
K2Cr2O7 / H2SO4 acidified
KMnO4/H2SO4 acidified
Benedict’s
Fehling’s
;
ketone
aldehyde
orange
no change
green
purple
no change
colourless
(v. Pale pink)
Schiff’s colouless → pink with CHO
violet
7
(c)
Equation: CH3CH2CH2CH2OH (or C4H9OH) + 2[O] → CH3CH2CH2COOH
(or C3H7COOH) + H2O (1)
Name of product: butanoic acid (1)
Accept butaneoic acid
2
[12]
Page 110 of 184
M20.
(i)
Isomer
Name
CH3CH2CH2CH2OH
butan-1-ol
2-methylpropan-2-ol
(2-)methyl propan-1-ol (1)
NOT prop-1-ol
butan-2-ol (1)
OR 2-butanol
NOT but-2-ol
NOT hydroxy
No RE
Allow e in the names
2
(ii)
Structural (1)
OR chain and position(al)
3
[3]
M21.
(a)
(i)
(ii)
restricted rotation OR no rotation OR cannot rotate (1)
3
Page 111 of 184
(b)
(i)
Mechanism:
M1 and M2 independent
Curly arrows must be from a bond or a lone pair
Do not penalise sticks
Penalise M1 if
precedes (penalise this once)
Penalise incorrect δ+ δ– for M2
Penalise + on C atom for M2
Only allow M1 for incorrect haloalkane
Role of the hydroxide ion: nucleophile (1)
electron pair donor
lone pair donor
NOT nucleophilic substitution
Page 112 of 184
(ii)
Mechanism:
Only allow M1 and M2 for incorrect haloalkane unless RE on (i)
+ charge on H on molecule, penalise M1
M3 independent
M2 must be to correct C–C
M1 must be correct H atom
Credit M1 and M2 via carbocation mechanism
No marks after any attack of C
by OH–
Role of the hydroxide ion: base (1)
proton acceptor
accepts H+
7
[10]
M22.
CHCl3 + Cl2 → CCl4 + HCl (1)
(a)
(i)
(ii)
UV light / sunlight OR high T OR T ≥ 500°C (1)
maxT = 1000°C
NOT heat / light
Ignore pressure
2
Page 113 of 184
(b)
Initial step: Cl2 → 2Cl· (1)
Condition could be on first equation arrow
First propagation step: CHCl3 + Cl· →
+ Cl2 → CCl4 + Cl· (1)
Second propagation step:
A termination step:
OR 2
+ HCl (1)
+ Cl· → CCl4 (1)
→ C2Cl6
Not 2Cl·→ Cl2
Ignore additional termination steps
4
[6]
M23.
(a)
(i)
A molecule/compound/it consists/it is composed/it is made up of
hydrogen/H and carbon/C only (1)
QoL
(ii)
release (heat) energy (when burned) (1)
OR provides a (useable form of) energy
OR is a source of energy
Accept heat energy
NOT is energy / is heat
NOT burns exothermically
(iii)
C4H10 + 6½O2 → 4CO2 + 5H2O (1)
OR 2C4H10 + 13 O2 → 8CO2 + 10H2O
ignore state symbols
(iv)
C4H10 + 4½O2 → 4CO + 5H2O (1)
OR 2C4H10 + 9O2 → 8CO + 10H2O
ignore state symbols
(iii) and (iv) if not C4H10 = CE
(v)
Limited or reduced supply of air / oxygen (1)
OR low temperature OR poor mixing
OR insufficient oxygen / air OR shortage of O2
NOT no oxygen / lack of oxygen / not in excess
5
Page 114 of 184
(b)
Structure 1
Structure 2
Structure 3
allow credit for positive charge around C atom
no alternative carbocations allowed
2
(c)
(i)
C2H6 / CH3CH3 → CH2=CH2 / H2C=CH2 / C2H4 + H2 / CH2CH2
NOT CH2.CH2
(ii)
Al2O3 OR Zeoli(y)te OR aluminosilicate (1)
NOT bauxite
ignore SiO2
NOT Aluminium Silicate
NOT porous pot
NOT SiO2 alone
(iii)
More useful / needed fuels / products OR implied
OR more valuable products
OR qualified demand exeeds supply
OR to produce motor fuels OR petrol OR cycloalkanes OR
aromatic hydrocarbons OR balanced alkanes OR smaller
molecules OR alkenes
3
[10]
M24.
(a)
K2Cr2O7/H2SO4 reuced by
CH3CH2CH2CH2OH (1)
oxidised to
CH3(CH2)2CHO (1)
and
CH3(CH2)2COOH (1)
CH3CH2CH2CHO (1)
oxidised to
Equation:
CH3(CH2)2COOH (1)
Cr2O72– + 14H+ + 6e– → 2Cr3+ + 7H2O (1)
Note: Deduct one if all three compounds given as reducing agents.
6
Page 115 of 184
(b)
Tollens’ reduced by
CH3CH2CH2CHO (1)
oxidised to
Equation
CH3(CH2)2COOH (1)
[Ag(NH3)2]+ + e– → Ag + 2NH3 (1)
3
(c)
CH3CH2CH2CH2OH (1)
Product CH3CH2CH2CH2OOCCH3 (1)
(CH3)3COH
Product (CH3)3COOCCH3 (1)
4
(d)
CH3CH2CH2OH has five peaks (1)
(CH3)3COH has two peaks (1)
2
[15]
M25.
(a)
Reaction 2: NaOH OR KOH (1) M1
ignore heat
alcohol (ic) OR ethanol (ic)(1) M2
Condition mark linked to correct reagent but award M2 if OH– or
base or alkali mentioned
Reaction 3: concentrated H2SO4 OR H3PO4 M1 (1) heat (1) M2
OR 150°C - 200°C
Condition mark linked to correct reagent but award M2 if H2SO4 or
H3PO4, but not concentrated
Penalise reagent and condition if dilute H2SO4 / H3PO4
4
Page 116 of 184
(b)
Mechanism:
Award M3
independently
M1 and M2 must be to / from correct places
E1 mechanism possible in which M2
Name: of mechanism = elimination (1)
NOT dehydrohalogenation
Ignore “base” OR “nucleophilic” before elimination
Reason: Reaction 2 has (very) low yield (1)
5
QoL OR chloroethane has to be made (from ethane)
OR chloroethane is expensive
OR chloroethane is not redily available
(c)
Mechanism:
Name of mechanism = elimination (1)
NOT dehydration alone
Reason: Ethanol could come from (fermentation of) renewable
QoL sugars / glucose / carbohydrates / sources (1)
6
[15]
Page 117 of 184
M26.
(a)
(i)
UV light OR sunlight OR T
NOT high T
(ii)
(free) radical substitution (1)
(iii)
CCl4 (1) OR named
450°C (1)
3
(b)
(i)
CH3Cl + KCN → CH3CN + KCl (1)
CN–
Cl–
(ii)
nucleophilic substitution (1)
(iii)
C–Br bond is weaker (than C–Cl bond)
OR C–Br bond enthalpy is less than C–Cl (1)
Ignore electronegativity
3
(c)
CH3COOH OR ethanoic acid (1)
1
(d)
(i)
OR C–Cl is polar (1) OR C atom is electron deficient / δ+
(ii)
methylamine (1) only
(iii)
SN1 scores full marks
6
[13]
M27.
(a)
(i)
C8H18 + 8½O2 → 8CO + 9H2O (1)
OR double this equation
(ii)
Condition: Spark OR high T OR T = 2500 – 4000 °C (1)
Equation: N2 + O2 → 2NO (1)
OR half this equation
3
Page 118 of 184
(b)
(i)
platinum OR rhodium OR palladium (1)
(ii)
2CO + 2NO → N2 + 2CO2 (1)
OR half this equation
2
(c)
Reason for SO2 in exhaust gases: fraction / petrol / fuels contain sulphur
or sulphur-containing impurities (which burn to give SO2) (1)
Environmental effect SO2: acid rain OR a specific effect (1)
NOT greenhouse effect
NOT damages ozone layer
2
[7]
M28.
(a)
(i)
A molecule / compound / Consists / composed of hydrogen
and carbon only (1)
or clearly implied
(ii)
only single bonds (or clearly implied) (1)
OR has no double bond
NOT has maximum number of hydrogen atoms
2
(b)
(i)
Fractional distillation OR fraction (1)
(ii)
Name of fraction
Number of carbon atoms
LPG (liquefied petroleum gas)
1–4
Petrol (gasoline)
4 – 12
Naphtha
7 – 14
Kerosine or Kerosene or Paraffin (1)
(Ignore uses)
11 – 15
Gas oil (diesel)
15 – 19
Mineral oil (lubricating oil)
20 – 30
Fuel oil
30 – 40
2
Page 119 of 184
(c)
(i)
C10H22 only (1)
NOT CH3CH2CH2CH2CH2CH2CH2CH2CH2CH3
(ii)
C14H30 → 2C2H4 + C3H6 + C7H16
OR C14H30 → 4C2H4 + 2C3H6 + H2
(1) alkene formula (1) balanced
(iii)
(free) radical OR homolysis OR homolytic fission (1)
NOT radical substitution
NOT thermal decomposition
4
[8]
M29.
(a)
1
1
NB
The bonds shown in the structure must be correct
Isomerism: Geometric or cis-trans
If written answer is correct, ignore incorrect labelling of structures.
If no written answer, allow correctly labelled structures.
1
Both COOH groups must be on the same side/ close together/ cis
1
No rotation about C=C axis
1
Structure
1
Page 120 of 184
(b)
Br2 / HBr / H2SO4 / H+ / Br+ / NO2+ (Mark M1)
NB If electrophile H+ / Br+ / NO2+ allow M1, M2 and M4
If the acid is incorrect, M2 and M3 can still be scored
Allow M4 consequentially if repeat error from part (a)
4
(c)
e.g. 2NaOH + HO2CCHCHCO2H → NaO2CCHCHCO2Na + 2H2O
Both H replaced
1
Balanced for atoms and charges
1
NB Allow ionic equations and
2NaOH + C4H4O4 → C4H2O4Na2+ 2H2O
Allow one if structure incorrect but molecular formula
correct
Allow one for a correct equation showing one H replaced
(d)
M1
Two peaks
1
M2
No splitting or singlets
1
M3
(Two) non-equivalent protons or two proton environments
1
M4
No adjacent protons
1
M5
Same area under the two peaks or same relative intensity
1
NB Doublet could score M1 and M3 or M5 (Max 2)
More than two peaks CE = 0
Apply the “list principle” to incorrect answers if more
than 3 given
Max 3
[15]
Page 121 of 184
M30.
(a)
(i)
(Free) radical substitution
(Both words needed)
1
(ii)
M1 initiation ONLY
1
M2 ultra-violet light OR sunlight OR 1000°C
T
450 °C
(Ignore reference to temperature if included with uv light)
(Penalise “high temperature” for M2)
1
(iii)
→ C2H6
(OR CH3CH3 as alternative to C2H6)
1
(iv)
CH3Br + Br2 → CH2Br2 + HBr
1
(b)
(i)
Electron pair donor
OR species with an electron pair able to form a covalent bond.
1
(ii)
Methylamine
(Credit “aminomethane”)
1
(iii)
1
M1 arrow to show breakage of C – Br bond
1
M2 arrow from lone pair on N of NH3 to form bond with C
1
M4 arrow from bond of N – H to N atom of CH3
3
(Ignore partial charges on haloalkane but penalise if incorrect)
(Accept
for M3)
(Full credit for carbocation mechanism; M1 for C – Br bond
breakage and M2 for lone pair attack on carbocation)
(Second mole of ammonia not essential to mechanism for full
credit)
1
[11]
Page 122 of 184
M31.
(a)
(i)
Potassium (OR sodium) dichromate(VI) OR correct formula
OR potassium manganate(VII)
(Oxidation state not needed, but must be correct if included)
(Penalise errors in the formula or oxidation state, but mark
conditions)
1
Acidified OR H2SO4 / HCl (NOT with KMnO4) / H3PO4 / HNO3
(Ignore heat or reflux)
(Credit “acidified” as part of reagent)
1
Oxidation or redox
1
(ii)
NaBH4 OR LiAlH4 OR H2/Ni
1
CH3COCH3 + 2[H] → CH3CH(OH)CH3
(Credit H2 in the equation if H2 has been chosen as reagent)
1
(b)
(i)
(Structure must show aldehyde structure)
(Credit C2H5 as alternative to CH3CH2)
Page 123 of 184
(ii)
M1 Tollens’
reagent OR
ammoniacal silver
nitrate
OR AgNO3 + NH3
M2 stays colourless
OR Fehling’s
solution
OR acidified
potassium
dichromate
1
stays blue
stays orange
1
(Provided reagent is correct, credit “no reaction”, “no change”,
“nothing”, “no observation” for M2)
M3 silver mirror /
deposit
OR black / grey
precipitate
red / brown / orange
precipitate / solid
goes green
1
(Credit other correct reagents and observation)
(For M1, penalise AgNO3 alone, penalise Ag(NH3) , penalise
“potassium dichromate”, etc., but, in each case, mark on and credit
correct M2 and M3)
(If totally wrong reagent or no reagent, CE = no marks for M1,M2
or M3)
1
[9]
M32.
(a)
(i)
Electrophilic addition
(Both words required)
1
(ii)
M1 the reaction to form 1-bromopropane goes via the primary
carbocation OR 1o carbocation
OR via
M2 primary carbocations are less stable than secondary carbocations
(Credit converse arguments for M1 and M2 i.e. the reaction to form
2-bromopropane goes via the secondary carbocation , M1, and
secondary carbocations are more stable than primary
carbocations, M2)
(Accept the use of “carbonium ions” as an alternative to
carbocation)
1
Page 124 of 184
(b)
M1 NaOH OR KOH OR correct name
1
M2 aqueous or solution in water (ignore heat, reflux etc.)
(Penalise M1 for hydroxide ion alone, but mark on and credit M2)
(Credit M2 ONLY for H2O as reagent and heat / warm / T=50 to
100oC)
(NaOH(aq) scores M1 and M2 provided it is not contradicted)
(Penalise M2 if NaOH(aq) followed by concentrated or ethanol)
(Penalise M1 and M2 if followed by acid)
1
(c)
Ethanolic OR alcoholic OR CH3CH2OH / CH3OH solvent OR
aqueous ethanol/alcohol
OR higher temperature (must be comparative)
(Ignore heat or heat under reflux)
(Credit part (c) independently from part (b))
(Penalise “ethanoic”)
1
(d)
(i)
Secondary OR 2o
1
(ii)
M1 arrow from double bond to H of H – O bond
M2 arrow from bond to oxygen atom to show H – O bond breakage
M4 arrow from lone pair of electrons to carbon atom of carbocation
(Penalise M1 if arrow goes to H2SO4 or to formal positive charge on
H, but ignore partial charges on sulphuric acid unless wrong)
(Credit M2 for H+ ion)
(For M4, accept negative charge anywhere on the ion)
4
(iii)
Catalyst ONLY
(Ignore homogeneous, heterogeneous)
1
[12]
M33.
(a)
(i)
C6H12O6 → 2C2H5OH + 2CO2
(Or CH3CH2OH)
(Ignore state symbols in the equation)
1
(ii)
Fermentation
1
Page 125 of 184
(b)
(i)
C2H5OH + 3O2 → 2CO2 + 3H2O
(Or C2H6O or CH3CH2OH)
1
(ii)
CO or carbon monoxide or C or carbon ONLY
1
(iii)
2CO + 2NO → 2CO2 + N2
OR 2NO → N2 + O2
OR 2NO + C → N2 + CO2
OR C8H18 + 25NO → 8CO2 + 12½N2 + 9H2O
(In equation 2, allow additional O2 on both sides of the equation)
1
(c)
Elimination
(Penalise additional words such as “electrophilic”)
1
M1 structure of protonated alcohol (allow CH3CH2
)
1
M2 arrow to show breakage of C – O bond on protonated alcohol
1
M3 structure of carbocation (allow
)
1
M4 arrow from correct C – H bond on carbocation
(penalise ‘sticks’ once only for structures M1 and M3)
(synchronous mechanism using correct structure required for M1,
loses M3)
1
Page 126 of 184
(d)
Silver OR silver-based
(NOT silver oxide)
1
1
M2 correct structure for epoxyethane
(Allow CH2=CH2 or C2H4 in the equation)
(Credit the structure of epoxyethane independently)
(Credit M1 provided O2 has been used and the atoms balance, but
the structure is poor e.g. C2H4O or CH2OCH2 but NOT CH3CHO)
1
[13]
M34.
(a)
(i)
An appropriate alkene; CH3CH2CHCH2 or (CH3)2CCH2
1
Isomer 1
1
Isomer 2
1
Position isomerism
1
Mechanism
electrophilic attack and electron shift to Br (Unless H+ used)
1
carbocation
1
reaction with carbocation
[Allow mechanism marks for the alkene CH3CHCHCH3]
[Allow one mark if mechanism for minor product given]
1
Page 127 of 184
(ii)
An appropriate carbonyl; CH3CH2CHO
1
Mechanism nucleophilic attack and electron shift to O
1
anion intermediate
1
reaction with anion
[Allow mechanism marks for the carbonyl (CH3)2CO]
1
Isomer 1
1
Isomer 2
1
Optical isomerism
NB Isomer structures must be tetrahedral
NB Penalise “stick” structures once in part (a)
1
(b)
QoL
Large charge on carbonyl carbon atom due to bonding
to O and Cl
1
Nucleophiles have electron pairs which can be donated
1
Equation Species
1
Balanced
1
[18]
M35.
(a)
M1 X is 1,2-dibromoethane only
1
M2 electrophilic addition
(both words needed)
1
M3 the double bond is a centre of electron density
OR electron-rich
OR nucleophilic
OR a source of an electron pair
OR a pi cloud/bond of electrons
1
M4 a dipole or polarity is induced/created/formed in the
Br-Br bond/molecule award this mark only if the quality of language justifies the award.
1
Page 128 of 184
(b)
nucleophilic substitution
(both words needed)
1
Mechanism M1 curly arrow from lone pair on oxygen of hydroxide
ion to C atom of C-Br
1
Mechanism M2 curly arrow from C-Br bond to side of Br atom
(a possible repeat error here from Question 4a)
(award a maximum of one mark for the wrong haloalkane)
(credit an SNl mechanism in which Ml will be a curly arrow from the
lone pair on oxygen of the hydroxide ion to the correct positive
carbon atom)
1
Y is susceptible to attack by hydroxide ions for one of the following
reasons
o
the C-Br bond is polar
o
the carbon atom is partially positive (or shown as such)
o
the carbon atom is electron deficient
1
(c)
M1 oxygen
(ignore “air”)
1
M2 silver or silver-based
(penalise silver nitrate)
1
M3 Z is epoxyethane
1
M4 epoxyethane
o
has a strained ring structure
o
has a bond angle of 60°
o
has a bond angle significantly less than tetrahedral
(ignore “unstable”, “has strained bonds”, “is stressed”)
1
Page 129 of 184
(d)
Ethane-1,2-diol is used in antifreeze
OR in the manufacture of PET/Terylene/polyester
(penalise “solvent” or “plasticiser”)
1
Hazard in Route via X/Y
o
bromine is toxic or corrosive
o
sodium hydroxide is corrosive or caustic
1
Hazard in Route via epoxyethane
o
risk of explosion in reaction 4
o
epoxyethane is toxic
o
epoxyethane is a respiratory irritant
o
epoxyethane causes neurological damage
1
[15]
M36.
(a)
M1
fermentation
1
M2
dehydration or elimination
1
(b)
(i)
yeast OR zymase OR an enzyme
1
(ii)
concentrated sulphuric or phosphoric acid
(penalise aqueous or dilute as a contradiction)
1
(c)
(i)
primary or 1°
1
(ii)
sugar or glucose or ethanol is renewable
OR ethanol does not contain sulphur-containing impurities
OR ethanol produces less pollution or is less smoky or less CO/C
(the objective is a positive statement about ethanol)
(penalise the idea that ethanol is an infinite source or vague
statements that ethanol has less impurities) (penalise the idea that
ethanol produces no pollution)
1
(d)
C2H6 → C2H4 + H2
1
Page 130 of 184
(e)
Addition
(ignore self or chain as a preface to “addition “)
(penalise additional)
1
[8]
M37.
(a) M1 curly arrow from lone pair on oxygen of hydroxide ion to
H atom on C-H adjacent to C-Br
1
M2 curly arrow from single bond of adjacent C-H
to adjacent single bond C-C
(only credit M2 if M1 is being attempted to correct H atom)
1
M3 curly arrow from C-Br bond to side of Br atom
(credit M3 independently)
1
(b)
Ml credit a correct structure for either geometrical isomer and its
designation as either cis or trans.
OR credit two correct geometrical isomer structures
(ignore the names)
OR credit two correct names for cis pent-2-ene and trans
pent-2-ene (ignore the structures)
1
M2 credit a second mark if all four parts of the required structures and
names are correct.
(credit “linear” structures)
(insist on the alkyl groups being attached clearly by C-C bonds)
1
(c)
(i)
Ml curly arrow from middle of C = C bond to H atom on H-Br
(penalise M1 if partial negative charge or formal positive
charge on H)
(penalise Ml if pent-2-ene is used)
1
M2 curly arrow from H-Br bond to side of Br atom
1
M3 correct structure for correct secondary carbocation
1
M4 curly arrow from lone pair on bromide ion to the positive
carbon of carbocation, ensuring that bromide ion has a
negative charge.
(with the exception of pent-2-ene, if the wrong alkene is used, only
penalise the structure M3)
(penalise the use of two dots in addition to a covalent bond, once
only)
1
(ii)
1-bromopentane
1
Page 131 of 184
(iii)
Ml 2-bromopentane is formed via the secondary (or 2°)
carbocation
1
OR 1-bromopentane is formed via the primary (or 1°)
carbocation
M2 a secondary carbocation is more stable than a primary
carbocation award this mark only if the quality of language justifies
the award.
(the argument must involve clear statements about carbocations)
1
[12]
M38.
(a)
Compounds with the same molecular formula
1
but different structures due to different positions of the
same functional group on the same carbon skeleton/chain
1
(b)
Compound A is butan-1-ol only
1
Compound C is butanone or butan-2-one
(penalise but-1-ol, but allow repeat error for but-2-one)
(credit butane-1-ol)
1
(c)
(i)
oxidation or redox
1
(ii)
K2Cr2O7 or potassium dichromate(VI)
(penalise the dichromate ion or incorrect oxidation state,
but mark on)
1
acidified or H2SO4 (or other identified strong acid)
(penalise H+)
(do not credit the acid unless M1 has been correctly attempted)
1
(iii)
(heat under) reflux
OR use excess oxidising agent
1
(iv)
correctly drawn structure of 2-methylpropan-2-ol
(insist on clearly drawn C-C and C-0 bonds)
1
(v)
correctly drawn structure of methanoic acid
(insist on C-0 and C=O displayed in the formula)
1
Page 132 of 184
(d)
(i)
Tollens’ reagent or this whole reagent specified
(ammoniacal silver nitrate)
OR Fehling’s solution
OR acidified potassium dichromate(VI)
1
(ii)
correctly drawn structure of methylpropanal
(insist on C-H and C=O of aldehyde displayed in the formula)
1
[12]
M39.
(a)
F2 → 2F•
1
CH4 + F• → •CH3 + HF
1
•CH3 + F2 → CH3F + F•
1
•CH3 + F• → CH3F
1
OR 2•CH3 → C2H6
(allow credit on this occasion for 2F•→ F2)
(penalise incorrect symbol Fl, once only)
(penalise absence of radical dot once only)
(b)
CH3F + 3F2 → CF4 + 3HF
1
[5]
M40.
(a)
(i)
fractional distillation or fractionation
1
(ii)
C9H20 only
1
(iii)
C11H24 + 17O2 → 11CO2 + 12H2O
1
(iv)
C11H24 + 6O2 → 11C + 12H2O
1
Page 133 of 184
(b)
(i)
C10H22 → C3H6 + C7H16
1
(ii)
correctly drawn structure of methylpropene
(insist on clearly drawn C-C and C=C bonds)
1
(c)
Any two from
o
chemically similar or chemically the same or react in
the same way
o
same functional group
o
same general formula
o
differ by CH2
(penalise same molecular formula or same empirical formula)
2
[8]
M41.
(a)
M1:
CH3CH2CH2CH2OH;
1
M2:
CH3CH(OH)CH2CH3;
(penalise incorrect alcohols in part (a), but mark consequentially in
part (b) and in part (c), if relevant)
(if three alcohols drawn, award MAX. 1 mark)
1
(b)
M1, M2 and M3: Correct structures for butanal, butanone
and butanoic acid;
(award these structure marks wherever the structures appear, but
insist that the C=O is shown in each structure and additionally, the
C-O in the carboxylic acid
3
Page 134 of 184
M4:
balanced equation for the reaction of butan-1-ol
with [O] to produce butanal and water;
1
M5:
balanced equation for the reaction of butan-1-ol
with [O] to produce butanoic acid and water
OR
balanced equation for the reaction of butanal with [O] to
produce butanoic acid;
1
M6: balanced equation for the reaction of butan-2-ol with [O] to
produce butanone and water;
(Credit condensed structures or molecular formulas in each
equation, provided it is obvious to which reaction the equation
refers) (Insist that whatever formula is used in each equation that it
is a conventional representation of the compound; for example
penalise CH3CH2CH2COH for butanal)
1
(c)
M1:
M2:
Correct structure for 2-methylpropan-2-ol;
2-methylpropan-2-ol
1
OR
methylpropan-2-ol;
(penalise on every occasion in parts (a) and (c), structures for the
alcohols that are presented with the alcohol functional group as CH-O)
1
[10]
M42.
M1:
uv light/sunlight
OR
T = 450 °C to 1000 °C;
(do not credit “high temperature”)
(ignore references to pressure or catalyst)
(penalise M1 if aqueous chlorine OR chlorine water)
(credit M1 if the condition appears over the arrow of the initiation
step)
1
Page 135 of 184
M2:
Cl2 → 2Cl.;
(credit correct half arrows, but penalise (once in the question) the
use of double headed arrows)
1
M3:
C2H6 + Cl. → CH3CH2. + HCl;
(credit CH3CH3 for ethane and C2H5- for the ethyl radical)
1
M4:
CH3CH2. + Cl2 → C2H5Cl + Cl.;
1
M5:
CH3CH2. + CH3CH2. → C4H10;
(penalise the absence of dots once only in this question)
(penalise subsequent ionic reactions as contradictions for each
reaction contradicted)
(if neither M3 nor M4 scored, allow CH3CH2. + Cl. → C2H5Cl for
one mark)
1
[5]
M43.
(a)
(i)
C6H12O6 → 2C2H5OH + 2CO2;
(penalise C2H6O once only in this question)
1
(ii)
Concentrated H2SO4 OR concentrated H3PO4 OR Al2O3;
(penalise aqueous or dilute as a contradiction)
1
C2H5OH → C2H4 + H2O OR C2H5OH → H2C = CH2 + H2O;
(penalise CH2.CH2 and CH2-CH2 and CH2 : CH2 for ethene)
1
(b)
Nickel OR Ni OR platinum OR Pt OR palladium OR Pd;
1
Hydrogen OR H2;
1
Page 136 of 184
(c)
(i)
C18H34O2 Only;
1
C9H17O
Only;
(empirical formula is not consequential on molecular formula)
1
(ii)
(An unsaturated compound) contains (at least) one double bond
OR
Contains C=C;
(must be a positive statement)
1
(iii)
M1: Bromine water
OR
Br2(aq)
OR
Bromine
OR
Br2;
(penalise “bromide water”, but mark on)
1
M1: decolourised or goes colourless
OR
from brown/red/orange/yellow to colourless;
(Must be “colourless” not “clear” for M2)
(chemical error if no reagent or wrong reagent, loses both marks)
(credit KMnO 4 for M1, (purple) to colourless for M2 (if acidified)
OR (purple) to brown/brown precipitate (if alkaline or unspecified)
(No credit for hydrogen or iodine as reagents)
1
[10]
M44.
(a)
2-bromobutane;
1
Page 137 of 184
(b)
Elimination;
(penalise “nucleophilic” OR “electrophilic” before the word
“elimination”)
1
M1: curly arrow from lone pair on oxygen of hydroxide ion to H atom
on correct C-H adjacent to C-Br;
(penalise M1 if KOH shown as covalent with an arrow breaking the
bond)
1
M2: curly arrow from single bond of adjacent C-H to adjacent
single bond C-C;
(only credit M2 if M1 is being attempted to correct H atom)
1
M3: curly arrow from C-Br bond to side of Br atom;
(credit M3 independently unless arrows contradict)
(Credit possible repeat error from 2(c)(iii) for M3)
(If the wrong haloalkane is used OR but-1-ene is produced, award
MAX. 2 marks for the mechanism)
(If E1 mechanism is used, give full credit in which M1 and M2 are
for correct curly arrows on the correct carbocation)
(c)
(i)
(structural) isomers/hydrocarbons/compounds/they have the same
molecular formula, but different structural formulas/different structures; 1
(penalise statements which are not expressed in good English and
which do not refer clearly to structural isomers i.e. plural)
(penalise statements which refer to “different (spatial)
arrangements”)
(credit” different displayed formulas”)
(Q of L mark)
(ii)
Correct structure for but-1-ene;
1
[7]
M45.
(a)
(i)
Electron pair/ lone pair acceptor OR seeking/bonds
with an electron pair
(insist on reference to a pair of electrons)
1
Page 138 of 184
(ii)
M1 curly arrow from middle of C=C bond of the alkene towards/
alongside the H atom of the H-Br;
(penalise arrows which go towards one of the carbon atoms)
(ignore a partial negative charge on the C=C)
1
M2 curly arrow from H-Br bond to side of Br atom;
(penalise M2 if there are formal charges on HBr or if there are
partial charges which are the wrong)
(penalise M2 if the single bond has two dots in addition to the line)
1
M3 correct structure for carbocation;
(penalise M3 if the positive charge is placed on the end of a bond)
(penalise M3 if any alkene other than ethene is used - all other
marks can score)
1
M4 curly arrow from lone pair on bromide ion to the positive carbon
of carbocation, ensuring that bromide ion has a negative charge;
(b)
(i)
M1 Oxygen OR O2;
(do not credit “air” alone, but otherwise ignore)
M2 silver OR Ag OR silver-based
(penalise silver nitrate)
1
(ii)
correct structure for epoxyethane;
(penalise poorly presented C-O bonds)
1
(iii)
water
OR
H2O;
(credit steam OR H2SO4 (aqueous OR dilute) OR NaOH(aq) OR
HCl(aq),
OR H3PO4(aq), but insist that (aq) is included)
(do not credit HCl or H2SO4 (concentrated or without water
present))
1
(c)
(i)
M1: potassium cyanide OR KCN OR sodium Cyanide OR NaCN;
(ignore conditions - dissolved in (aq) or (alc) or KOH(aq) all work)
(penalise HCN)
1
M2: propanenitrile;
(credit propan-1-nitrile OR propan nitrile, but not propanitrile)
1
Page 139 of 184
(ii)
M1: ammonia OR NH3;
(If formula is written, insist that it is correct)
(ignore conditions, but penalise acidic)
1
M2: ethylamine;
(credit aminoethane)
1
(iii)
M1: curly arrow from lone pair on nitrogen of (correct formula for)
ammonia towards/alongside C atom of C-Br;
(penalise M1 if formula of ammonia is wrong or has a negative
charge or has no lone pair or arrow is from negative charge)
1
M2: curly arrow from C-Br bond towards/alongside side Br atom;
(credit M2 independently)
(penalise M2 if formal positive charge on C atom of C-Br)
1
M3: correct structure of the ethylammonium ion;
(credit the structure drawn out with all four bonds around the
nitrogen atom OR written as C2H5NH3+ OR CH3CH2NH3+)
1
M4: curly arrow from the middle of one of the H-N bonds towards the
positive N atom;
(possible to credit M4 on an incorrect ethylammonium ion with no
positive charge)
(ignore use of ammonia or bromide ion etc. to remove proton from
ethylammonium ion)
(If the wrong haloalkane is used, award MAX. 3 marks for the
mechanism) (If SN1 mechanism is used, give full credit in which
M1 is for a curly arrow from the lone pair of the N atom of (correct
formula for) ammonia towards/alongside the positive carbon atom
of CH3CH2+)
[17]
M46.
(a)
(i)
compounds/mixtures/alkanes/hydrocarbons/molecules with a
boiling point range/similar boiling point/similar number of
carbon atoms/similar chain length;
(insist on “similar” rather than “same”)
(ignore references to size or Mr)
(penalise references to bond breaking/cracking as contradictions)
1
(ii)
molecules have different boiling points/intermolecular forces/sizes/chain
lengths/Mr;
(ignore references to melting points)
(credit the idea that molecules condense at different temperatures)
1
Page 140 of 184
(iii)
the column has a higher temperature at the base (Q of L mark)
OR
the column has a lower temperature at the top;
(the statement needs to be expressed in good English and show a
clear understanding of the correct temperature difference)
(penalise “negative OR positive temperature gradient” without
qualification to what the candidate means, otherwise ignore) (ignore
references to the boiling points of the molecules) (credit correct
statements which use specific temperatures with a maximum
temperature of 500 °C at the base)
1
(b)
(i)
C8H18 + 8½O2 → 8CO + 9H2O;
(or double this equation)
1
(ii)
correctly drawn structure of 2,2,3-trimethylpentane
(penalise the use of ‘sticks’ once on the paper, including the
structures in the 2(a)(ii) and 2(c)(iii )mechanisms) (credit correctly
condensed structures)
1
(c)
cracking produces/makes ethene/propene/alkenes/motor fuels/petrol
OR
cracking makes more useful products/high(er) value products
OR
cracking satisfies the high demand for small(er) products;
(ignore the idea that cracking makes or leads to plastics or
polyethene) (high demand needs to be qualified)
1
(d)
(i)
carbocation
OR
carbonium ion;
(do not credit examples or formulae, but otherwise ignore) (credit
“carbon cation”)
1
(ii)
zeolite
OR
aluminosilicate OR Al2O3;
1
Page 141 of 184
(e)
(i)
M1: (free) radical;
(credit alkyl radical)
(do not credit examples or formulae, but otherwise ignore)
(penalise “radical substitution” OR “hydrocarbon radical” as
contradictions)
1
M2: homolysis
OR
homolytic fission/splitting/cleavage
OR
C-C / C-H bonds break;
1
(ii)
alkene(s);
(credit “small or short chain alkenes”)
(penalise “cycloalkenes”)
(penalise additional types of compounds (e.g. branched alkanes)
as a
contradiction)
(do not credit examples or formulae, but ignore if these are correct
and in addition to the word “alkene”)
1
[11]
Page 142 of 184
M47.
(a)
M1: aqueous or solution in water or (aq) in the equation
1
M2: yeast or zymase
(do not credit ‘an enzyme’ unless qualified)
1
M3: anaerobic/absence of oxygen/absence of air or neutral pH/pH value 6 – 8
1
M4: T in the range 30 – 40 °C only
(ignore references to pressure)
(ignore uv light)
1
M5: fermentation
1
M6: C6H12O6 → 2CH3CH2OH + 2CO2
(ignore state symbols but penalise M1 if the state symbol in the
equation contradicts)
1
M7: CH3CH2OH + 3O2 → 2CO2 + 3H2O
(credit use of C2H5OH)
(penalise use of C2H6O once only in M6 or M7)
1
(b)
M1: dehydration is the elimination of water or removal
of combined water or qualified loss of/removal of water
e.g. from a compound/molecule/alcohol or removal of
H and O in the ratio 2:1 from a compound/ molecule/alcohol
(do not credit ‘from a ‘substance’)
(do not credit ‘removal of water molecules’ unless qualified from a
compound/molecule etc.)
1
M2: Catalyst = concentrated H2SO4 or concentrated/oily/syrupy
phosphoric acid or aluminium oxide/ pumice/porous pot
1
M3: CH3CH2OH → H2C=CH2 + H2O
(credit use of C2H5OH)
(penalise use of C2H6O here unless already penalised in part(a).
Possible credit as repeat error)
(credit C2H4 and CH2=CH2 for ethene, but penalise CH2CH2, CH2.
CH2, CH2:CH2)
(ignore H2SO4 if it appears on both sides of equation)
1
Page 143 of 184
(c)
M1: large(r) to small(er) molecules/hydrocarbons/compounds
or high(er) Mr alkanes to low(er) Mr alkanes (+ alkenes) (+ H2)
1
M2: breakage/homolysis/splitting of C–C/carbon chain/carbon skeleton
(do not credit breaking C–H bonds alone, but ignore if
accompanied by C–C)
1
M3: reactive intermediate is (free/alkyl) radical or radical mechanism
(do not credit ‘free radical substitution’ and penalise M3 as a
contradiction if mentioned with free radical intermediates)
1
M4: any T (or range) in the range 400 to 900°C or high temperature
(ignore ‘pressure’)
1
M5: CH3CH2CH2CH3 (OR C4H10) → H2C=CH2 + CH3CH3 (OR C2H6) or CH3CH2CH2CH3 (OR
C4H10) → 2H2C=CH2 + H2
(credit C2H4 and CH2=CH2 for ethene, but penalise CH2CH2,
CH2.CH2, CH2:CH2 and note possible RE from part(b))
1
[15]
M48.
(a)
(base) elimination
(penalise other words before ‘elimination’ e.g. nucleophilic)
1
M1: curly arrow from lone pair of electrons on oxygen of hydroxide ion
(insist on a lone pair of electrons on the oxygen atom and a
negative charge, but only credit this mark if the attack is to a
correct H atom)
1
M2: curly arrow from the middle of the C-H bond to the middle
of the C–C bond
1
(only credit this mark if the arrow originates from the correct C–H
bond and if an attempt has been made at M1)
M3: curly arrow from the middle of the C–Br bond towards/alongside
the Br atom
(credit M3 independently unless the bond breaking is contradicted
by an additional arrow)
(penalise curly arrow if the C–Br has a formal positive charge)
(credit full marks for an E1 mechanism, with M2 awarded for a
correct curly arrow on the correct carbocation)
(award a maximum of two marks for either an incorrect haloalkane
or an incorrect organic product)
(maximum 2 marks for use of 'sticks' for the haloalkane, unless
RE from 2(b), when credit can be given)
Page 144 of 184
(b)
(i)
M1: compounds with the same structural formula
1
M2: but the bonds/groups/atoms have different spatial
arrangements or orientation or configuration/are arranged
differently in space/3D
(ignore reference to the same molecular formula for M1)
1
(ii)
M1: correct structural representation for cis-but-2-ene and
its name or its identification as the cis isomer
1
M2: correct structural representation for trans-but-2-ene
and its name or its identification as the trans isomer
(accept representations which are 90° to linear)
(award one mark for two correct structures but either wrong/no
names)
(maximum 1 mark for an incorrect alkene)
1
(iii)
geometric(al) or cis-trans
1
(c)
nucleophile or electron pair donor
(penalise ‘base’)
1
(d)
CH3CH2CH2CH2Br + 2NH3 → CH3CH2CH2CH2NH2 + NH4Br
(M1 correct product)
(M2 balanced equation using 2NH3 and leading to NH4Br)
(penalise M1 for use of C4H9NH2 or for incorrect haloalkane, but
allow consequent correct balancing of equation with 2 moles of
ammonia)
2
(1–)butylamine
(credit 1–aminobutane and butyl–1–amine)
(award QoL mark for correct spelling)
1
[13]
M49.
1(-)bromobutane
1
correct structure for 1-bromo-2-methylpropane
(C–C bonds must be clear where drawn)
1
[2]
Page 145 of 184
M50.
(a)
(i)
(free–) radical substitution
(both words required for the mark)
1
initiation Cl2 → 2Cl·
(credit correct half arrows, but penalise double headed arrows)
1
first propagation CH3Cl + Cl· → ·CH2Cl + HCl
1
second propagation ·CH2Cl + Cl2 → CH2Cl2 + Cl
(penalise the absence of dots on radicals once only)
(penalise radical dot on Cl of CH2Cl once only)
1
(ii)
CH3Cl + Cl2 → CH2Cl2 + HCl
(penalise if any radicals appear in this equation)
1
(b)
M1: mol C = 10.1/12.0
and
mol Cl = 89.9/35.5
1
M2: Ratio 0.842 : 2.53
OR
1: 3
OR
CCl3
1
M3: 237.0/Mr of CCl3 = 237.0/118.5 = 2
Therefore C2Cl6
(correct answer gains full credit)
1
OR
M1: 237.0 × 10.1/100 and 237 × 89.9/100
1
M2: Ratio 23.9/12.0 : 213/35.5 OR 2 : 6
1
M3: C2Cl6
(correct answer gains full credit)
1
(c)
any two from CHBr3 or CBr4 or C2H2Br4 (or CHBr2CHBr2) or
C2Br6 (or CBr3CBr3)
(ignore HBr or H2)
(ignore equations and ignore names when given in addition to
formulae)
(penalise names alone)
2
[10]
Page 146 of 184
M51.
(a)
Ag or silver or silver-based or silver on an alumina base
(penalise specific silver compounds)
1
epoxyethane
1
(b)
electrophilic addition
1
M1: curly arrow from C=C bond towards/alongside the
side of H atom on H-OSO2OH
(penalise M1 if arrow to H2SO4 OR to formal charge on H
of H-O bond)
(ignore partial charges on H and O of H2SO4, but penalise
if these are incorrect on the H atom being attacked)
(credit M1 and M2 if correct curly arrow to H+ provided
the anion is present)
1
M2: curly arrow from H–O bond towards/alongside the side of the
O atom on H–OSO2OH
(credit the arrow even if there are partial or formal charges on H
and O but the structure of H2SO4 is correct)
1
M3: correct structure of the carbocation
(penalise use of ‘sticks’ in this structure)
1
M4: curly arrow from lone pair on an individual oxygen atom of
(correct formula for) hydrogensulphate ion towards/alongside C
atom bearing the positive charge
(insist that the an ion has the correct formula with a lone pair of
electrons and a negative charge)
1
(c)
(i)
ethanal
1
correct structure for ethanal
(aldehyde functional group must be drawn out)
1
(ii)
oxidation or redox
1
[10]
Page 147 of 184
M52.
(a)
(i)
any two from:
show a gradation/trend/gradual change in physical properties/
a specified property
differ by CH2
chemically similar or react in the same way
have the same functional group
(penalise ‘same molecular formula’)
(penalise ‘same empirical formula’)
2
(ii)
fractional distillation or fractionation
1
(iii)
contains only single bonds or has no double bonds
(credit ‘every carbon is bonded to four other atoms’ provided it
does not contradict by suggesting that this will always be H)
1
(b)
(i)
the molecular formula gives the actual number of atoms of each
element/type in a molecule/hydrocarbon/compound/formula
(penalise ‘amount of atoms’)
(penalise ‘ratio of atoms’)
1
(ii)
C14H30 only
(penalise as a contradiction if correct answer is
accompanied by other structural formulae)
1
(iii)
C10H22 + 5½O2 → 10C + 11H2O
(or double this equation)
1
Page 148 of 184
(c)
(i)
½N2 + ½O2 → NO
(or double this equation)
1
(ii)
Platinum or palladium or rhodium
1
(iii)
2CO + 2NO → 2CO2 + N2 or
2NO → N2 + O2 or
(ignore extra O2 molecules provided the equation balances)
C + 2NO → CO2 + N2
(or half of each of these equations)
C8H18 + 25NO → 8CO2 + 12½N2 + 9H2O
(or double this equation)
1
[10]
M53.
(a)
(i)
M1 pentan-3-one only
1
M2 CH3CH2CH2COCH3
(insist on C=O being drawn out)
(penalise use of C3H7)
1
(ii)
aldehyde
(CH3)2CHCH2CHO
1
ketone
(CH3)2CHCOCH3
1
(insist on a clear structure for the C=O of the functional groups, but
do not be too harsh on the vertical bonds between carbon atom son
this occasion)
(If both structures correct, but wrong way around, award one mark)
(ignore names)
(b)
(i)
CH3CH2CH2CH2CHO + [O] → CH3CH2CH2CH2COOH
(accept C4H9CHO going to C4H9COOH)
(insist on a balanced equation – for example do not credit [O] over
the arrow alone)
1
(ii)
pentanoic acid
(credit pentan–1–oic acid)
1
Page 149 of 184
(c)
(i)
CH3CH2CH2CH2CH2OH OR pentan–1–ol
(If both a structure and a formula are given, credit either correct
one of these provided the other is a good, if imperfect, attempt)
1
(ii)
Primary
(credit 1o or 1)
1
[8]
M54.
(a)
(i)
(free–)radical substitution
(both words required for the mark)
1
(ii)
uv light OR sunlight OR high temperature OR 150 °C to 500 °C
1
(iii)
Propagation
(ignore “chain”, “first”, “second” in front of the word propagation)
1
(iv)
Termination
1
•CH CH + Br•
2
3
OR 2•CH CH
2
3
CH3CH2Br
C4H10
(penalise if radical dot is obviously on CH3, but not otherwise)
(penalise C2H5•)
(credit 2Br•
Br2)
(ignore “chain” in front of the word termination)
1
(b)
(i)
Fractional distillation OR fractionation
(credit gas–liquid chromatography, GLC)
1
(ii)
CH3CH3 + 6Br2
C2Br6 + 6HBr
(credit C2H6 for ethane)
1
(c)
Correct structure for CF2BrCF2Br drawn out
(penalise “Fl” for fluorine)
1
Page 150 of 184
(d)
(i)
2–bromo–2–chloro–1,1,1–trifluoroethane
OR 1–bromo–1–chloro–2,2,2–trifluoroethane
(insist on all numbers, but do not penalise failure to use alphabet)
(accept “flourine” and “cloro” in this instance)
1
(ii)
197.4 only
(ignore units)
1
(iii)
(57/197.4 × 100) = 28.9% OR 28.88%
(credit the correct answer independently in part (d)(iii), even if (d)(ii)
is blank or incorrectly calculated, but mark consequential on part
(d)(ii), if part (d)(ii) is incorrectly calculated, accepting answers to
3sf or 4sf only)
(penalise 29% if it appears alone, but not if it follows a correct
answer)
(do not insist on the % sign being given)
(the percentage sign is not essential here, but penalise the use of
units e.g. grams)
1
[11]
M55.
(a)
(i)
M1 curly arrow from lone pair of electrons on oxygen of hydroxide ion
(insist on a lone pair of electrons on the oxygen atom and a
negative charge, but only credit this mark if the attack is to a
correct H atom)
1
M2 curly arrow from the middle of the C–H bond to the middle of
the C–C bond.
(only credit this mark if the arrow originates from the correct
C–H bond and if an attempt has been made at M1)
1
M3 curly arrow from the middle of the C–Br bond towards/alongside
the Br atom.
(credit M3 independently unless the bond breaking is
contradicted by an additional arrow)
(penalise M3 curly arrow if the C–Br has a formal positive charge)
(ignore partial charges on the C–Br bond, but penalise if incorrect)
(credit full marks for an E1 mechanism, with M2 awarded for a correct curly
arrow on the correct carbocation)
(award a maximum of two marks for an incorrect haloalkane)
(ignore products)
1
Page 151 of 184
(ii)
Haloalkane/C2H5Br is made from ethane
OR haloalkane is not (readily) available
OR haloalkane is expensive
OR it is (too) expensive/costly
OR (reaction) yield is too low/poor
OR it is too slow
OR a valid reference to nucleophilic substitution/alcohol formation
occurring as an alternative reaction.
(ignore references to temperature or to energy consumption)
(do not credit statements which refer to the idea that this route
is not chosen, because industry chooses another route e.g. cracking)
1
(b)
(i)
Strained ring/ bonds/ structure/molecule
OR three–membered ring
OR 60o bond angle
OR bond angle much less than tetrahedral
(penalise “stressed ring”)
(ignore “weak bonds”, ignore “unstable”)
1
(ii)
ethane–1,2–diol OR correct structure
(penalise ethylene glycol OR 1,2–dihydroxyethane if these appear alone)
(credit ethan–1,2–diol)
(If both a structure and a formula are given, credit either correct
one of these provided the other is a good, if imperfect, attempt)
1
(used in) antifreeze
OR
for OR in the manufacture/making/formation of terylene, polyester,
PET only
(ignore reference to terylene etc. if they accompany “antifreeze”
(penalise “de–icer”, “solvent”, “surfactant”, “plasticizer”)
(If the candidate indicates that the product is antifreeze ,then this
can gain credit, but not if contradicted in its use e.g. as de–icer)
1
[7]
M56.
(a)
hydration OR (electrophilic) addition
(penalise incorrect words in front of the word “addition” e.g.
“nucleophilic”)
(penalise “indirect hydration” but credit “direct hydration” or “steam
hydration”)
1
Page 152 of 184
H2C=CH2 + H2O → CH3CH2OH
(ignore state symbols)
(credit use of C2H5OH for ethanol)
(penalise use of C2H6O for ethanol on the first occasion)
(credit C2H4 and CH2=CH2 for ethene)
(penalise CH2CH2, CH2.CH2, CH2:CH2 for ethene on the first
occasion)
(ignore H2SO4 OR extra H2O OR H+ if it appears on both sides)
1
conc. H2SO4 OR conc. H3PO4
1
(b)
(i)
Carbon OR C
(credit “soot” or “sooty”)
(penalise “coke” or “coal”)
(credit “carbon + carbon monoxide” provided it is clear that carbon
is solid; penalise “carbon + carbon dioxide”)
1
(ii)
CH3CH2OH + O2 → 2C + 3H2O
OR
CH3CH2OH + 1½O2 → C + CO + 3H2O
(credit multiples of these equations)
(credit use of C2H5OH for ethanol)
(penalise use of C2H6O for ethanol, but note a possible repeat error
from part (a) above)
1
[5]
M57.
(a) Allow 1 mark each for any correctly drawn primary, secondary and
tertiary alcohol of molecular formula C4H8O
3
Tertiary alcohol cannot be oxidised
1
(b)
Region 1500–400 cm–1
1
exact match to spectrum of known compound
1
Page 153 of 184
(c)
A
CH3CH2CH2OH
B
CH3CH2–O–CH3 (1)
or CH3CH(OH)CH3 (1)
C
one alkene e.g.
D
one cycloalkane e.g.
CH2=CHCH2CH2CH3
CH3–CH=CH–CH2CH3
(CH3)2C=CHCH3
H2C=C(CH3)CH2CH3
(1)
etc
E
CH3CH2CHO (1)
F
CH3COCH3 (1)
6
[12]
M58.
(a)
(i)
If wrong carbocation, lose structure mark
If wrong alkene, lose structure mark
Can still score ¾ i.e. penalise M3
Penalise M2 if polarity included incorrectly
no bond between H and Br
bond is shown as
or
4
(ii)
CH3CH2CH2
credit secondary carbocation here if primary carbocation has
been used in (i)
Ignore attack on this carbocation by
o
1
Page 154 of 184
(b)
(i)
Structure:
1
Name: propan-2-ol
Not 2-hydroxypropane
1
(ii)
Name of mechanism: nucleophilic substitution (both words)
(NOT SN1 or SN2)
1
Mechanism:
penalise incorrect polarity on C-Br (M1)
Credit the arrows even if incorrect haloalkane
If SN1, both marks possible
2
(c)
(i)
elimination
1
(ii)
base
OR proton acceptor
NOT nucleophile
1
[12]
M59.
(a)
(i)
Prevents release of toxic CO
More energy efficient (releases more energy on combustion)
1
(ii)
C6H14 + 6.5O2 → 6CO + 7H2O
1
Suitable product eg CO or C
1
Balanced equation
1
(iii)
Detect CO gas or C (soot or particles) in exhaust gases
1
Page 155 of 184
(b)
CH3CH2CH2CH(CH3)2
1
2-methylpentane
1
CH3CH2CH(CH3)CH2CH3 etc
1
(c)
(i)
CH3CH2CH2CH=CH2
1
(ii)
Alumino silicate etc
1
(iii)
Can be made into polymers (or alcohols etc)
1
(d)
(i)
% atom economy = mass CH2Cl2/total mass
reactants = 85 × 100/158
1
= 53.8%
1
(ii)
Because expensive chlorine is not incorperated into
desired product Raise money by selling HCl
1
[14]
M60.
(a)
Single bonds only /no double or multiple bonds;
1
Contains carbon and hydrogen only;
C and H only
not C and H molecules
1
Alkanes;
1
Page 156 of 184
(b)
(1) Fractions or hydrocarbons or compounds have different
boiling points/ separation depends on bp;
Ignore mp and vdw
1
(2) bp depends on size/ M r/ chain length;
If refer to bond breaking/cracking/ blast furnace/oxygen/air 2 max
1
(3) Temp gradient in tower or column / cooler at top of column
or vice versa;
QWC
1
(4) Higher bp / larger or heavier molecules at bottom (of
column) or vice versa;
Not increasing size of fraction
Not gases at top
1
(c)
Large molecules or compounds or long chain hydrocarbons
(broken) into smaller molecules or compounds or smaller
chain hydrocarbons;
QWC
1
Zeolite or aluminosilicate (catalyst);
1
C14H30 → C8H18 + C6H12;
Only
1
Smaller chain molecules are in more demand or have higher
value or vice versa;
Insufficient to say more useful/have more uses
1
(d)
C8H18 + 8½ O2 → 8CO + 9H2O;
Allow multiples
1
Rh/ Pd/Pt/lr or in words;
Penalise contradiction of name and symbol
1
2CO + 2NO → 2CO2 + N2 / 2CO + O2 → 2CO2;
Allow multiples
1
Greenhouse gas/ absorbs infrared radiation;
1
Page 157 of 184
(e)
car less powerful/ car stops/ reduced performance/ won’t run
smoothly/ can’t accelerate;
Not incomplete combustion or bad effect on engine
Not doesn’t go as far.
1
Test it (before sale) /Quality control etc;
1
(f)
(compounds with) same molecular formula / same no and type of atoms;
Not atoms/elements with same molecular formula.
If same chemical formula, can allow M2
1
And different structure/ structural formula;
M2 consequential on M1
Allow displayed formula for M2
1
2,2,4-trimethylpentane;
Only (but allow numbers in any order)
1
[20]
M61.
(a)
M1
(Free-) radical substitution
Both words needed
1
M2
Cl2 → 2Cl•
1
M3
Cl• + CH4 → •CH3 + HCl
1
M4
Cl2 + •CH3 → CH3Cl + Cl•
1
M5
CH4 + 3Cl2 → CHCl3 + 3HCl
Penalise the absence of a radical dot once only
Ignore termination steps except, if and only if both M3 and M4
do not score, then accept for one mark
Cl• + •CH3 → CH3Cl
1
Page 158 of 184
(b)
M1
UV (light)/ sunlight / light / UV radiation
M2
C–Cl or carbon-chlorine bond breakage
OR
homolysis of C–Cl
OR
equation to show a chlorine-containing organic
compound forming two radicals
For M1 and M2, ignore use of Cl2, but credit UV and C–Cl bond
breakage if seen
1
M3
Cl• + O3 → ClO• + O2
1
M4
ClO• + O3 → Cl• + 2O2
Ignore other equations
Penalise the absence of a radical dot once only
Accept radical dot anywhere on either radical.
1
M5
Any one from
•
Combination 2O3 → 3O2
•
Stated that Cl• / chlorine atom is regenerated / not used up
•
Stated that the Cl• / chlorine atom is unaffected
by the process.
1
For M5 accept Cl• on both sides of the equation
M6
Stated that the role of the Cl• / chlorine atom is to find an
alternative route OR lower Ea / activation energy
1
(c)
M1
Halothane contains C–Cl / Cl
OR
Desflurane does not contain C–Cl bonds / Cl
OR
Desflurane contains C–F / F as the only halogen
Mark independently.
For M1, credit the idea that desflurane contains C–F bonds that are
difficult to break OR that halothane contains C–Cl bonds which are
easy to break.
1
M2
Desflurane / molecules that have fluorine as the only
halogen, cause no damage / do not deplete / do not react
with the ozone (layer)
OR
Halothane / chlorine-containing molecules, damage /
deplete / react with the ozone (layer)
1
[13]
Page 159 of 184
M62.
(a) Electron pair donor
OR
Species which uses a pair of electrons
to form a co-ordinate / covalent bond.
QoL
Credit “lone pair” as alternative wording
1
(b)
M1
Must show an arrow from the lone pair of electrons
on the carbon atom of the negatively charged
cyanide ion to the central C atom.
M2
Must show the movement of a pair of electrons from
the C-Br bond to the Br atom. Mark M2 independently.
Award full marks for an SN1 mechanism in which M1 is the
attack of the cyanide ion on the intermediate carbocation.
Penalise M1 if covalent KCN is used
Penalise M2 for formal charge on C or incorrect partial charges
Penalise once only for a line and two dots to show a bond.
Max 1 mark for the wrong reactant or “sticks”
2
(c)
Ethylamine / CH3CH2NH2 is a nucleophile
OR
Ethylamine could react further
OR
Ethylamine could make secondary / tertiary amines
OR
To make reaction with ammonia more likely
OR
To minimise further substitution
OR
The idea of releasing free amine from the salt
OR
The idea of removing a proton from the intermediate
alkylammonium ion
OR
The idea that ammonia acts both initially as a nucleophile and
then as a base
Do not credit a simple reference to the equation or the mechanism
requiring two moles of ammonia.
1
Page 160 of 184
(d)
Elimination
Credit “base elimination” but NOT “nucleophilic elimination”
No other prefix.
1
M1
Must show an arrow from the lone pair on oxygen of a
negatively charged hydroxide ion to the correct H atom
M2
Must show an arrow from the correct C-H bond to the
C-C bond and should only be awarded if an attempt has
been made at M1
M3
Is independent.
Award full marks for an E1 mechanism in which M2 is on the
correct carbocation.
Mechanism
Penalise M1 if covalent KOH
Penalise M3 for formal charge on C or incorrect partial charges
Penalise once only for a line and two dots to show a bond.
Max 2 marks for the mechanism for wrong reactant or “sticks”
3
[8]
M63.
(a)
Contains a C=C OR a double bond
1
Page 161 of 184
(b)
Electrophilic addition
Both words needed
1
Mechanism:
Ignore partial negative charge on the double bond.
M2 Penalise partial charges on bromine if wrong way and penalise
formal charges
Penalise once only in any part of the mechanism for a line and two
dots to show a bond.
M1
Must show an arrow from the double bond towards one
of the Br atoms on a Br-Br molecule.
Deduct 1 mark for sticks.
M2
Must show the breaking of the Br-Br bond.
M3
Is for the structure of the secondary carbocation with Br substituent.
M4
Must show an arrow from the lone pair of electrons on a
negatively charged bromide ion towards the positively
charged carbon atom.
Deduct 1 mark for wrong reactant, but mark consequentially.
If HBr, mark the mechanism consequentially and deduct one mark
If but-1-ene, mark the mechanism consequentially and deduct one
mark.
If both HBr and but-1-ene, mark the mechanism consequentially
and deduct ONLY one mark.
4
(c)
(i)
M1
Compounds with the same structural formula
Penalise M1 if “same structure”
Ignore references to “same molecular formula” or “same empirical
formula”
1
M2
With atoms/bonds/groups arranged differently in space
OR
atoms/bonds/groups have different spatial
arrangements/ different orientation.
Mark independently.
1
Page 162 of 184
(ii)
Award credit provided it is obvious that the candidate is drawing the
trans isomer.
Do not penalise poor C–C bonds
Trigonal planar structure not essential
1
[9]
M64.
(a)
General formula;
Chemically similar;
Same functional group;
Trend in physical properties eg inc bp as M r increases;
Contains an additional CH2 group;
Any two points.
2 max
(b)
(i)
All bonds and atoms must be shown.
1
C3H6Cl;
Allow any order of elements.
Do not allow EF consequential on their wrong displayed formula.
1
(ii)
Same Molecular formula/ both C6H12Cl2/ same number and type
of atoms;
1
Different structural formula/ different structure/ different
displayed formula;
Not atoms or elements with same MF
CE=O.
Allow different C skeleton.
If same chemical formula can allow M2 only.
M2 insufficient to say atoms arranged differently.
M2 consequential on M1.
1
Page 163 of 184
(c)
M r =228 for total reactants;
1
= 67.98%;
Allow 67.98 or 68.0 or 68%.
1
(d)
(i)
Bp increases with increasing (molecular) size/ increasing M r/
increasing no of electrons/increasing chain length;
Atoms CE =0.
1
Increased VDW forces (between molecules) (when larger
molecule)/ bigger IMFs;
QWC
Not dipole-dipole or hydrogen bonds.
If VDW between atoms in M2 CE = 0.
1
(ii)
Fractional distillation/ fractionation/ GLC/chromatography;
1
[11]
M65.
(a)
(i)
Covalent;
If not covalent CE = 0.
If blank, mark on.
1
Shared pair of electrons (one from each atom);
Not shared electrons.
1
(ii)
Hydrogen bonds / H bonds;
Not just hydrogen.
1
Van der Waals/London/dispersion forces/temporary
induced dipole;
1
(b)
Showing all the lone pairs on both molecules;
Allow showing both lone pairs on the O involved in the H-bond.
1
Showing the partial charges on O and H on both molecules;
Allow showing both partial charges on the O and H of the other
molecule involved in the H bond.
1
Showing the Hydrogen bond from the lone pair on O of one
molecule to the delta + on the H of the other molecule;
1
Page 164 of 184
(c)
(i)
C2H5OH + 3O2 → 2CO2 + 3H2O;
Accept multiples.
Allow C2H6O.
1
(ii)
CO is (produced which is) toxic/ poisonous/C (may be produced)
which is toxic/ C is a respiratory irritant/ C (particles) exacerbate
asthma/C causes global dimming/ smog;
Must relate to C or CO.
Any mention of SO2 NO2 or other pollutants CE = 0.
1
(iii)
More fuel needed (which costs more)/Wastes fuel/
less fuel burnt (so need more to buy more)/engine gets sooty so
need to pay for engine to be cleaned/Have to fit catalytic converter;
Not just costs more.
Not engine gets sooty unless qualified.
1
(d)
(i)
(React) with CaO/ calcium oxide/quicklime/lime;
Accept CaCO3/ calcium carbonate/limestone.
Not chalk.
1
All the sulfur dioxide may not react with the CaO or CaCO3 /
may not have time to react/ incomplete reaction;
Accept incomplete reaction.
1
(ii)
Occupies a (much) smaller volume;
Not easier to store or transport.
1
[13]
Page 165 of 184
M66.
(a)
nucleophilic addition
1
Attack by HCN loses M1 and M2
M2 not allowed independent of M1, but
allow M1 for correct attack on C+
+C=O loses M2
M2 only allowed if correct carbon attacked
allow minus charge on N i.e. :CN–
4
M3 for completely correct structure not including lp
allow C3H7 in M3
M4 for lp and arrow
allow without –
1
2-hydroxy-2-methylpentan(e)nitrile
allow 2-hydroxy-2-methylpentanonitrile
(b)
Product from Q is a racemic mixture/equal amounts of enantiomers
if no reference to products then no marks;
1
racemic mixture is inactive or inactive explained
not Q is optically active or has a chiral centre etc
1
Product from R is inactive (molecule) or has no chiral centre
1
(c)
(i)
mark the three sections of (c) separately
1
R or CH3CH2COCH2CH3
(ii)
[CH3CH2COCH2CH3]+. OR [C5H10O]+.
1
→ [CH3CH2CO]+ + .CH2CH3
OR → [C3H5O]+ + .C2H5
1
allow molecular formulae
allow without brackets
if brackets not shown, allow dot anywhere on radical or + anywhere
on ion
Page 166 of 184
(iii)
m/z = 43 or 71
1
[13]
M67.
(a) M1
Displayed formula for butan-2-ol
M1 displayed formula must have all bonds drawn out, including the
O―H but ignore angles
Penalise “sticks”
M2 Alcohol X is
M2 structure must be clearly identifiable as
2-methylpropan-2-ol and may be drawn in a variety of ways.
M3 Alcohol Y is named (2)-methylpropan-1-ol ONLY
M3 must be correct name, but ignore structures
3
(b)
M1 The infrared spectrum shows an absorption/peak in the range
3230 to 3550 (cm–1)(which supports the idea that an alcohol is present)
In M1, allow the words “dip”, “spike”, “low transmittance” and
“trough” as alternatives for absorption.
M2 Reference to the ‘fingerprint region’ or below 1500 (cm–1)
M3 Match with or same as known sample/database spectra
Check the spectrum to see if alcohol OH is labelled and credit.
OR
M2 Run infrared spectra (of the alcohols)
M3 Find which one matches or is the same as this spectrum.
3
Page 167 of 184
(c)
M1 balanced equation
C6H12O6 → CH3CH2CH2CH2OH + 2CO2 + H2O
or C4H9OH
Or multiples for M1 and M3
In M1 and M3 penalise use of C4H10O or butan-2-ol once only
M2 Any one from
•
excess/adequate/sufficient/correct amount of/enough/plenty/
a good supply of oxygen or air
•
good mixing of the fuel and air/oxygen
For M2, do not accept simply “oxygen” or “air” alone
Ignore reference to “temperature”
M3 CH3CH2CH2CH2OH + 6O2 → 4CO2 + 5H2O
or C4H9OH
M4 A biofuel is a fuel produced from (renewable) biological (re)source(s)
OR
(renewable) (re)source(s) from (a specified) plant(s)/fruit(s)/tree(s)
In M4
Ignore references to “carbon neutral”
Ignore “sugar” and “glucose”
4
(d)
M1 butan-1-ol is a primary or 1° (alcohol)
M2 Displayed formula (ONLY) for butanal CH3CH2CH2CHO
M3 Displayed formula (ONLY) for butanoic acid CH3CH2CH2COOH
M2 and M3 displayed formula must have all bonds drawn out
including the O―H but ignore angles.
If butanal and butanoic acid formulae are both correctly given but
not displayed, credit one mark out of two.
M4 Oxidation (oxidised) OR Redox
M5 orange to green
Both colours required for M5
Ignore states
5
[15]
Page 168 of 184
M68.
(a)
(i)
Nucleophilic substitution
1
2
M1 must show an arrow from the lone pair of electrons on the
oxygen atom of the negatively charged hydroxide ion to the
central C atom.
M2 must show the movement of a pair of electrons from the
C-Br bond to the Br atom. Mark M2 independently.
Penalise M1 if covalent KOH is used
Penalise M2 for formal charge on C or incorrect partial charges
Penalise once only for a line and two dots to show a bond.
Max 1 mark for the mechanism for the wrong reactant and/or
“sticks”
Ignore product
Award full marks for an SN1 mechanism in which M1 is the
attack of the hydroxide ion on the intermediate carbocation.
(ii)
2-bromopropane ONLY
1
(iii)
Polar C–Br OR polar carbon–bromine bond OR dipole on C–Br
OR δ+ (δ–)
C atom of carbon–bromine bond is δ+/electron deficient OR C―Br
(Credit carbon–halogen bond as an alternative to
carbon–bromine bond)
It must be clear that the discussion is about the carbon atom of the
C–Br bond. NOT just reference to a polar molecule.
Ignore X for halogen
1
Page 169 of 184
(b)
Elimination
Credit “base elimination” but NOT “nucleophilic elimination”
No other prefix.
1
3
M1 must show an arrow from the lone pair on oxygen of a negatively
charged hydroxide ion to the correct H atom
M2 must show an arrow from the correct C-H bond to the C-C bond
and should only be awarded if an attempt has been made at M1
M3 is independent.
Mechanism
Penalise M1 if covalent KOH
Penalise M3 for formal charge on C or incorrect partial charges
Penalise once only for a line and two dots to show a bond.
Max 2 marks for the mechanism for wrong reactant and/or
“sticks”
Ignore product
Award full marks for an E1 mechanism in which M2 is on the
correct carbocation.
(c)
Any one condition from this list to favour elimination;
Apply the list principle
•
alcohol(ic)/ethanol(ic) (solvent)
•
high concentration of KOH/alkali/hydroxide OR concentrated
KOH/hydroxide
Ignore “aqueous”
•
high temperature or hot or heat under reflux or T = 78 to 100°C
Ignore “excess”
1
(d)
(i)
Addition (polymerisation) ONLY
Penalise “additional”
1
(ii)
But-2-ene ONLY (hyphens not essential)
Ignore references to cis and trans or
E/Z
Ignore butane
1
[12]
Page 170 of 184
M69.
(a)
Functional group (isomerism)
1
(b)
M1 Tollens’ (reagent)
(Credit ammoniacal silver nitrate OR
a description of making Tollens’)
(Ignore either AgNO3 or [Ag(NH3)2+]
M1 Fehling’s (solution) or
Benedict’s solution
(Ignore Cu2+(aq) or
CuSO4 on their own, but mark on
or “the silver mirror test” on their
own, but mark M2 and M3)
to M2 and M3)
M2 silver mirror
M2 Red solid/precipitate
(Credit orange or brown solid)
OR
black solid/precipitate
(NOT silver precipitate)
M3 (stays) colourless
or no change or no reaction
M3 (stays) blue
or no change or no reaction
Mark on from an incomplete/incorrect attempt at the correct
reagent, penalising M1
No reagent, CE=0
Allow the following alternatives
M1 (acidified) potassium dichromate(VI) (solution)
M2 (turns) green
M3 (stays) orange/no change
OR
M1 (acidified) potassium manganate(VII) (solution)
M2 (turns) colourless
M3 (stays) purple/no change
For M3
Ignore “nothing (happens)”
Ignore “no observation”
3
(c)
(Both have) C=O OR a carbonyl (group)
1
(d)
(i)
(Free-) radical substitution ONLY
Penalise “(free) radical mechanism”
1
Page 171 of 184
(ii)
Initiation
Cl2 → 2Cl•
Penalise absence of dot once only.
First propagation
Cl• + CH3CH2CH3 → •CH2CH2CH3 + HCl
OR C3H8
Penalise incorrect position of dot on propyl radical once only.
Penalise C3H7• once only
Second propagation
Cl2 + •CH2CH2CH3 → CH3CH2CH2Cl + Cl•
OR
C3H7Cl
Accept CH3CH2CH2• with the radical dot above/below/to the side of
the last carbon.
Termination (must make C6H14)
2 •CH2CH2CH3 → C6H14 or CH3CH2CH2CH2CH2CH3
Use of the secondary free radical might gain 3 of the four marks
4
(e)
M r = 44.06352 (for propane)
M r = 43.98982 (for carbon dioxide)
Mark independently
M1 a correct value for both of these M r values.
M2 a statement or idea that two peaks appear (in the mass spectrum)
OR
two molecular ions are seen (in the mass spectrum).
2
[12]
M70.
(a)
(i)
single (C-C) bonds only/no double (C=C) bonds
1
Allow all carbon atoms bonded to four other atoms
Single C-H bonds only = 0
C=H CE
C and H (atoms) only/purely/solely/entirely
Not consists or comprises
Not completely filled with hydrogen
CH molecules = CE
Element containing C and H = CE
1
Page 172 of 184
(ii)
CnH2n+2
Formula only
CxH2x+2
1
(b)
(i)
C5H12 + 8O2 → 5CO2 + 6H2O
Accept multiples
Ignore state symbols
1
(ii)
gases produced are greenhouse gases/contribute to Global
warming/effect of global warming/climate change
Allow CO2 or water is greenhouse gas/causes global warming
Acid rain/ozone CE = 0
1
(c)
carbon
Allow C
Allow soot
1
(d)
(i)
C9H20 → C5H12 + C4H8
OR
C9H20 → C5H12 + 2C2H4
Accept multiples
1
(ii)
Plastics, polymers
Accept any polyalkene/haloalkanes/alcohols
1
(iii)
so the bonds break OR because the bonds are strong
IMF mentioned = 0
1
(e)
(i)
1,4-dibromo-1-chloropentane/1-chloro-1,4-dibromopentane
Ignore punctuation
1
(ii)
Chain/position/positional
Not structural or branched alone
1
[11]
Page 173 of 184
M71.
(a)
Three conditions in any order for M1 to M3
M1
yeast or zymase
M2 30 °C ≥ T ≤ 42 °C
M3
anaerobic/no oxygen/no air OR neutral pH
M4
C6H12O6
OR
2C6H12O6
2C2H5OH + 2CO2
4C2H5OH + 4CO2
Mark independently
Penalise “bacteria” and “phosphoric acid” using the list principle
Ignore reference to “aqueous” or “water” (i.e. not part of the list
principle)
Or other multiples
4
(b)
M1
Carbon-neutral
Ignore “biofuel”
1
M2
6 (mol/molecules) CO2/carbon dioxide taken in/used/used
up (to form glucose or in photosynthesis)
1
M3
6 (mol/molecules) CO2/carbon dioxide given out due to
2 (mol/molecules) CO2/carbon dioxide from fermentation/
Process 2 and 4 (mol/molecules) CO2/carbon dioxide from
combustion/Process 3
It is NOT sufficient in M2 and M3 for equations alone without
commentary or annotation or calculation
1
(c)
M1
(could be scored by a correct mathematical expression)
(Sum of) bonds broken – (Sum of) bonds made/formed = ΔH
OR
(Σ) Breactants – (Σ) Bproducts = ΔH
(where B = bond enthalpy/bond energy)
For M1 there must be a correct mathematical expression using ΔH
or “enthalpy change”
M2
Reactants = (+) 4719
OR
Products = (–) 5750
Page 174 of 184
M3
Overall + 4719 – 5750 = –1031 (kJ mol–1) (This is worth 3 marks)
Award full marks for correct answer.
Ignore units.
M2 is for either value underlined
M3 is NOT consequential on M2
3
Award 1 mark ONLY for +1031
Candidates may use a cycle and gain full marks.
M4
Mean bond enthalpies are not specific for this reaction
OR they are average values from many different
compounds/molecules
Do not forget to award this mark
1
(d)
M1
q = m c ΔT (this mark for correct mathematical formula)
M2
= 6688 (J) OR 6.688 (kJ) OR 6.69 (kJ) OR 6.7 (kJ)
M3
0.46g is 0.01 mol
therefore ΔH = – 669 kJ mol–1 OR – 670 kJmol–1
OR –668.8 kJ mol–1
Award M1, M2 and M3 for correct answer to the calculation
Penalise M3 ONLY if correct answer but sign is incorrect
In M1, do not penalise incorrect cases in the formula
If m = 0.46 or m = 200.46 OR if ΔT = 281, CE and penalise M2 and
M3
If c = 4.81 (leads to 7696) penalise M2 ONLY and mark on for M3
= –769.6 OR –770
Ignore incorrect units in M2
M4
Incomplete combustion
Do not forget to award this mark. Mark independently
4
[15]
Page 175 of 184
M72.
(a)
(i)
Cl2
M1
Initiation
2Cl•
M2 First propagation
Cl• + CH3CH3
•CH2CH3 + HCl
C2H6
M3 Second propagation
Cl2 + •CH2CH3
CH3CH2Cl + Cl•
C2H5Cl
M4
Termination (must make C4H10)
2 •CH2CH3
C4H10 or CH3CH2CH2CH3
Penalise absence of dot once only.
Penalise + or – charges every time
Penalise incorrect position of dot on ethyl radical once only.
Penalise C2H5• once only
Accept CH3CH2 • with the radical dot above/below/to the side of the
CH2
Mark independently
4
(ii)
M1 ultra-violet/uv/sun light
OR (very) high temperature OR 500 °C ≥ T ≤1000 °C
M2
(free-)radical substitution
Ignore “heat” for M1
Both words needed for M2
For M2, ignore the word “mechanism”
2
(b)
(i)
Cl2 + H2O
HClO + HCl
OR
Cl2 + H2O
2H+ + ClO– + Cl–
Accept HOCl or ClOH
Accept other ionic or mixed representations
Ignore state symbols
1
Page 176 of 184
(ii)
M1
•
•
•
•
Any one from
in swimming pools
in drinking water
to sterilise/disinfect/sanitise water
in water treatment
Ignore the manufacture of bleach
Ignore “to clean water”
Ignore “water purification”
M2
The (health) benefit outweighs the risk or wtte
OR a clear statement that once it has done its job,
little of it remains OR used in (very) dilute concentrations/
small amounts/low doses
Mark independently but M1 can score from (M2) explanation
2
(iii)
Sodium chlorate(I) or sodium hypochlorite
Must be named
Ignore (in)correct formulae
Insist on the (I) in the name
1
(c)
(i)
Cl2 + 2Br–
Br2 + 2Cl–
Or half this equation
Ignore state symbols
1
(ii)
M1
The relative size (of the molecules/atoms)
Bromine is larger than chlorine OR has more
electrons/electron shells
OR It is larger/It has a larger atomic radius/it is a
larger molecule/atom
M2
How size of the intermolecular force affects
energy needed
The forces between bromine/Br2 molecules are
stronger (than the forces between chlorine/Cl2
molecules leading to more energy needed to
separate the molecules) (or converse)
OR bromine/Br2 has stronger/more (VdW) intermolecular
forces.
(or converse)
For M1 ignore whether it refers to molecules or atoms.
CE = 0 for reference to (halide) ions
Ignore molecular mass
QoL for clear reference to the difference in size of the force
between molecules
Penalise M2 if covalent bonds are broken
2
[13]
Page 177 of 184
M73.
(a)
(i)
3-bromo-3-methylpentane ONLY
Must be correct spelling but ignore hyphens and commas
1
(ii)
Electrophilic addition (reaction)
Both words needed
Accept phonetic spelling
1
(iii)
M1
Displayed formula of 2-bromo-3-methylpentane
All the bonds must be drawn out but ignore bond angles
M2
Position(al) (isomerism)
Do not forget to award this mark
2
(iv)
Structure of (E)-3-methylpent-2-ene
The arrangement of groups around the double bond must be clear
with the ethyl group attached in the correct order. Ignore bond
angles.
Accept C2H5 for ethyl
Be lenient on C ─ C bonds. The main issue here is whether they have drawn an (E) isomer.
Accept “sticks” for C ─ H bonds and correct skeletal formula
1
Page 178 of 184
(b)
(i)
M1
R is represented by Spectrum 2
M2
Spectrum 2 shows an infrared absorption/spike/dip/
trough/peak with any value(s)/range within the range 1620 to
1680 (cm–1) OR this range quoted/identified and this
is due to C=C
OR this information could be a correctly labelled absorption
on the spectrum
OR Spectrum 1 does not have an infrared absorption in range
1620 to 1680 (cm–1) and does not contain C=C.
Award M1 if it is obvious that they are referring to the second
spectrum (or the bottom one)
M2 depends on a correct M1
Ignore other correctly labelled peaks
Ignore reference to “double bond” or “alkene”
2
(ii)
Functional group (isomerism)
1
(iii)
Cyclohexane
OR
Methylcyclopentane etc.
Named correctly
Ignore structures and ignore numbers on the methyl group of
methylcyclopentane
1
[9]
M74.
(a)
to neutralise stomach acidity
OR
as an antacid
OR
eases indigestion/heartburn
Ignore milk of magnesia
Credit suitable reference to indigestion/laxative/relief of constipation
1
(b)
(i)
an electron acceptor
OR
(readily) gains/accepts/receives electron(s)
NOT an electron pair acceptor
Ignore removes/takes away/attracts electrons
1
Page 179 of 184
(ii)
Br2 ONLY
Ignore “bromine”
Apply the list principle
1
(iii)
H2SO4 + 2H+ + 2e–
SO2 + 2H2O
OR
SO42– + 4H+ + 2e–
SO2 + 2H2O
Ignore state symbols
Ignore absence of negative charge on electron
Or multiples of equations
1
(c)
(i)
(acid) catalyst
OR
catalyses (the reaction)
OR
to speed up the reaction/increase the rate (of reaction)
Ignore “provides H+ ions”
Accept phonetic spelling
1
(ii)
M1
must show an arrow from the double bond towards the
H atom of the H – O bond OR HO on a compound with
molecular formula for H2SO4 (or accept H2SO3 here)
M1 could be to an H+ ion and M2 an independent
O – H bond break on a compound with molecular
formula for H2SO4 or H2SO3
M2
must show the breaking of the O ─ H bond.
M3
must show an arrow from the lone pair of electrons on the
correct oxygen of the negatively charged ion towards the
positively charged carbon atom.
Page 180 of 184
M4
is for the structure of the carbocation.
NB The arrows here are double-headed
M2 Ignore partial charges unless wrong
M3 NOT HSO4–
For M3, credit as shown or ―:OSO3H ONLY with the negative
charge anywhere on this ion
OR correctly drawn out with the negative charge placed correctly
on oxygen
Max 3 marks for wrong reactant
Do not penalise the use of “sticks”
4
(iii)
Primary OR 1° (alcohol)
1
(iv)
Displayed formula for ethanoic acid, CH3COOH
All the bonds must be drawn out and this includes the O ─ H bond
Ignore bond angles.
1
[11]
M75.
(a)
to neutralise stomach acidity
OR
as an antacid
OR
eases indigestion/heartburn
Ignore milk of magnesia
Credit suitable reference to indigestion/laxative/relief of constipation
1
(b)
(i)
an electron acceptor
OR
(readily) gains/accepts/receives electron(s)
NOT an electron pair acceptor
Ignore removes/takes away/attracts electrons
1
Page 181 of 184
(ii)
Br2 ONLY
Ignore “bromine”
Apply the list principle
1
(iii)
H2SO4 + 2H+ + 2e–
SO2 + 2H2O
OR
SO42– + 4H+ + 2e–
SO2 + 2H2O
Ignore state symbols
Ignore absence of negative charge on electron
Or multiples of equations
1
(c)
(i)
(acid) catalyst
OR
catalyses (the reaction)
OR
to speed up the reaction/increase the rate (of reaction)
Ignore “provides H+ ions”
Accept phonetic spelling
1
(ii)
M1
must show an arrow from the double bond towards the
H atom of the H – O bond OR HO on a compound with
molecular formula for H2SO4 (or accept H2SO3 here)
M1 could be to an H+ ion and M2 an independent
O – H bond break on a compound with molecular
formula for H2SO4 or H2SO3
M2
must show the breaking of the O ─ H bond.
M3
must show an arrow from the lone pair of electrons on the
correct oxygen of the negatively charged ion towards the
positively charged carbon atom.
Page 182 of 184
M4
is for the structure of the carbocation.
NB The arrows here are double-headed
M2 Ignore partial charges unless wrong
M3 NOT HSO4–
For M3, credit as shown or ―:OSO3H ONLY with the negative
charge anywhere on this ion
OR correctly drawn out with the negative charge placed correctly
on oxygen
Max 3 marks for wrong reactant
Do not penalise the use of “sticks”
4
(iii)
Primary OR 1° (alcohol)
1
(iv)
Displayed formula for ethanoic acid, CH3COOH
All the bonds must be drawn out and this includes the O ─ H bond
Ignore bond angles.
1
[11]
Page 183 of 184
Page 184 of 184