Alkenes
11.5What the syllabus asks of you
- State that the bonding in alkenes includes a double carbon–carbon covalent bond and that alkenes are unsaturated hydrocarbons
- Describe the manufacture of alkenes and hydrogen by the cracking of larger alkane molecules using a high temperature and a catalyst
- Describe the reasons for the cracking of larger alkane molecules
- Describe the test to distinguish between saturated and unsaturated hydrocarbons by their reaction with aqueous bromine
- State that in an addition reaction only one product is formed
- Describe the properties of alkenes in terms of addition reactions with: (a) bromine or aqueous bromine (b) hydrogen in the presence of a nickel catalyst (c) steam in the presence of an acid catalyst and draw the structural or displayed formulae of the products
Read the notes first
Chapter 11: Alkenes
Drill this topic
Every question on Alkenes, untimed, marked as you go.
Make a worksheet
Choose the years and how many questions, then print it with the answers on separate pages.
45 questions
1May / June 2026 · Paper 11 · Q32Show mark scheme →
AQ does not burn in air.
BQ is a saturated hydrocarbon.
CQ reacts with bromine to form a single product with molecular formula CxHy–1Br.
DQ reacts with steam to form a single product with molecular formula CxHy+2O.
Mark scheme
2May / June 2026 · Paper 11 · Q34Show mark scheme →
Aby polymerisation reactions
Bby the addition of hydrogen to unsaturated vegetable oils
Cby the combustion of alkanes
Dby the cracking of hydrocarbons
Mark scheme
3May / June 2026 · Paper 12 · Q33Show mark scheme →
ACH3CHBrCH2CH2Br
BCH3CHBrCHBrCH3
CCH2BrCH2CH2CH2Br
DCH3CH2CH2CH2Br
Mark scheme
4Oct / Nov 2025 · Paper 11 · Q34Show mark scheme →
ACH3CHCHCH3
BCH3CH2CH2CH3
CCH3CH2CH2COOH
DCH3CH2CH2CH2OH
Mark scheme
5Oct / Nov 2025 · Paper 12 · Q34Show mark scheme →
APropene is a saturated hydrocarbon because it has a double carbon–carbon bond in its molecule.
BPropene is the third member of the homologous series of alkenes.
CPropene reacts with bromine in a substitution reaction that results in the rapid decolourisation of the bromine.
DPropene reacts with hydrogen in the presence of a nickel catalyst to produce propane.
Mark scheme
6May / June 2025 · Paper 11 · Q36Show mark scheme →
Acracking; heat with nickel catalyst
Bfractional distillation; heat with acid catalyst
Ccracking; heat with acid catalyst
Dfractional distillation; heat with nickel catalyst
Mark scheme
7May / June 2025 · Paper 12 · Q34Show mark scheme →
A1: one molecule; 2: an alcohol
B1: one molecule; 2: a carboxylic acid
C1: two molecules; 2: an alcohol
D1: two molecules; 2: a carboxylic acid
Mark scheme
8Oct / Nov 2024 · Paper 11 · Q32Show mark scheme →
AC10H22 → 2C2H4 + C3H6 + C4H10
BC10H22 → H2 + 2C2H4 + C3H6 + C5H10
CC10H22 → 2C3H6 + C4H10
DC10H22 → H2 + 2C2H4 + 2C3H6
Mark scheme
9Oct / Nov 2024 · Paper 11 · Q33Show mark scheme →
AEthene and bromine react to produce 1,1-dibromoethane.
BPropene and bromine react to produce 1,3-dibromopropane.
CBut-2-ene and bromine react to produce 2,2-dibromobutane.
DBut-1-ene and bromine react to produce 1,2-dibromobutane.
Mark scheme
10Oct / Nov 2024 · Paper 12 · Q36Show mark scheme →
AAlkenes are unsaturated which means that they are less soluble in water than alkanes.
BAlkenes contain a higher percentage by mass of carbon than alkanes.
CCracking large alkanes produces only smaller alkanes and hydrogen.
DThe presence of a double bond in an alkene means that 1 mol of alkene will react with exactly 80.0 g of bromine.
Mark scheme
11Oct / Nov 2023 · Paper 12 · Q17Show mark scheme →
Airon / alkane
Biron / alcohol
Cnickel / alkane
Dnickel / alcohol
Mark scheme
12May / June 2023 · Paper 12 · Q36Show mark scheme →
A1, 2 and 3
B1 and 2 only
C1 and 3 only
D2 and 3 only
Mark scheme
13May / June 2022 · Paper 11 · Q36Show mark scheme →
Abutanol | high pressure and a catalyst | combustion
Bbutanol | heat and a catalyst | decomposition
Cpropanol | heat and a catalyst | decomposition
Dpropanol | heat and a catalyst | combustion
Mark scheme
14May / June 2022 · Paper 12 · Q34Show mark scheme →
ACH4
BC2H4
CC2H6
DCH3OH
Mark scheme
15May / June 2022 · Paper 12 · Q35Show mark scheme →
Acracking; reaction with steam
Bcracking; fermentation
Cfractional distillation; reaction with steam
Dfractional distillation; fermentation
Mark scheme
16Oct / Nov 2021 · Paper 11 · Q37Show mark scheme →
A1 and 2
B1 and 4
C2 and 3
D3 and 4
Mark scheme
17Oct / Nov 2021 · Paper 11 · Q38Also set in Oct / Nov 2018 Paper 12Show mark scheme →
Aaddition
Bfermentation
Cpolymerisation
Dreduction
Mark scheme
18Oct / Nov 2021 · Paper 12 · Q37Show mark scheme →
AQ does not burn in air.
BQ is a saturated hydrocarbon.
CQ reacts with bromine to form a single product with molecular formula CₓHᵧ₋₁Br.
DQ reacts with steam to form a single product with molecular formula CₓHᵧ₊₂O.
Mark scheme
19May / June 2021 · Paper 11 · Q36Show mark scheme →
AIt is a saturated hydrocarbon.
BIt is an isomer of butene.
CIt will decolourise bromine water.
DIts name is propane.
Mark scheme
20May / June 2021 · Paper 12 · Q36Show mark scheme →
Ais added, increases
Bis removed, decreases
Cis added, decreases
Dis removed, increases
Mark scheme
21Oct / Nov 2020 · Paper 11 · Q17Show mark scheme →
AThey contain equal numbers of atoms.
BThey give equal volumes of carbon dioxide when burnt completely in oxygen.
CThey give equal masses of ethane and propane when reacted with hydrogen.
DThey react with equal masses of bromine.
Mark scheme
22Oct / Nov 2020 · Paper 11 · Q35Show mark scheme →
A1 and 2 only
B1 and 3 only
C2 and 3 only
D1, 2 and 3
Mark scheme
23Oct / Nov 2020 · Paper 12 · Q35Show mark scheme →
Acombustion with oxygen
Bhydrogenation
Cpolymerisation
Dreaction with steam
Mark scheme
24Oct / Nov 2020 · Paper 12 · Q36Show mark scheme →
Ais unsaturated: P; reacts with aqueous bromine: P
Bis unsaturated: P; reacts with aqueous bromine: Q
Cis unsaturated: Q; reacts with aqueous bromine: P
Dis unsaturated: Q; reacts with aqueous bromine: Q
Mark scheme
25May / June 2020 · Paper 11 · Q34Show mark scheme →
Aone molecule | an alcohol
Bone molecule | a carboxylic acid
Ctwo molecules | an alcohol
Dtwo molecules | a carboxylic acid
Mark scheme
26May / June 2020 · Paper 11 · Q35Show mark scheme →
A1 only
B3 only
C1 and 2
D2 and 3
Mark scheme
27May / June 2020 · Paper 12 · Q35Show mark scheme →
AAn alkene molecule contains four fewer hydrogen atoms than an alkane molecule with the same number of carbon atoms.
BIf a food is described as polyunsaturated it means that it contains polymers.
CPropene reacts with steam to form propanol.
DThe general formula for the alkenes is CnH2n+2.
Mark scheme
28Oct / Nov 2019 · Paper 12 · Q32Show mark scheme →
AIt decolourises aqueous bromine.
BIt has a sweet smell.
CIt is a good solvent for organic compounds.
DIt produces carbon dioxide when burned.
Mark scheme
29Oct / Nov 2019 · Paper 12 · Q34Also set in Oct / Nov 2019 Paper 11Show mark scheme →
AH-C(Br)(Br)-C(H)(H)-C(H)(H)-C(H)(H)-H
BH-C(Br)(Br)-C(H)(H)-C(H)(H)-C(H)(H)-H
CH-C(Br)(H)-C(H)(H)-C(Br)(H)-C(H)(H)-H
DH-C(Br)(H)-C(H)(H)-C(H)(H)-C(Br)(H)-H
Mark scheme
30Oct / Nov 2019 · Paper 12 · Q35Show mark scheme →
AIt can be formed by cracking butane.
BIt has the formula C3H8.
CIt is a saturated hydrocarbon.
DIt reacts with hydrogen to form ethane.
Mark scheme
31May / June 2019 · Paper 11 · Q35Show mark scheme →
AH2, CnH2n
BH2, CnH2n+2
CH2O, CnH2n
DH2O, CnH2n+2
Mark scheme
32May / June 2019 · Paper 12 · Q35Show mark scheme →
Amaking ethane and ethene from butane
Bmaking ethene and hydrogen from butane
Cthe manufacture of margarine from a vegetable oil
Dthe reaction between ethene and oxygen, giving carbon dioxide and water
Mark scheme
33Oct / Nov 2018 · Paper 12 · Q36Also set in Oct / Nov 2018 Paper 11Show mark scheme →
ABoth are liquids at room temperature.
BBoth occur naturally.
CMargarine has the higher melting point.
DVegetable oil has fewer carbon-carbon double bonds than margarine.
Mark scheme
34May / June 2018 · Paper 11 · Q37Show mark scheme →
AH2C=CH-CH3 (propene, structure A)
Bbranched alkane structure B
Cstraight-chain alkane structure C
Dbranched alkene structure D
Mark scheme
35May / June 2018 · Paper 12 · Q37Show mark scheme →
ACH3CHBrCH2CH2Br
BCH3CHBrCHBrCH3
CCH2BrCH2CH2CH2Br
DCH3CH2CH2CH2Br
Mark scheme
36Oct / Nov 2017 · Paper 11 · Q36Show mark scheme →
ACnH2n+2, no change
BCnH2n+2, the aqueous bromine is decolourised
CCnH2n, no change
DCnH2n, the aqueous bromine is decolourised
Mark scheme
37May / June 2017 · Paper 11 · Q36Show mark scheme →
AW and Y
BW and Z
CX and Y
DX and Z
Mark scheme
38Oct / Nov 2016 · Paper 11 · Q38Show mark scheme →
AC6H8
BC6H10
CC6H14
DC6H16
Mark scheme
39Oct / Nov 2016 · Paper 12 · Q30Show mark scheme →
AHelium is used in balloons because it is unreactive and less dense than air.
BHydrogen is used in an addition reaction with saturated vegetable oils to form margarine.
CNitrogen from the air is used in the manufacture of ammonia.
DOxygen is used in making steel and welding.
Mark scheme
40Oct / Nov 2016 · Paper 12 · Q37Also set in Oct / Nov 2016 Paper 11Show mark scheme →
Aargon
Bhydrogen
Coxygen
Dsteam
Mark scheme
41Oct / Nov 2016 · Paper 12 · Q39Show mark scheme →
A1
B2
C3
D4
Mark scheme
42May / June 2016 · Paper 11 · Q37Show mark scheme →
Aby polymerisation reactions
Bby the addition of hydrogen to unsaturated vegetable oils
Cby the combustion of alkanes
Dby the cracking of hydrocarbons
Mark scheme
43May / June 2016 · Paper 12 · Q34Show mark scheme →
A1
B2
C3
D4
Mark scheme
44May / June 2016 · Paper 12 · Q35Show mark scheme →
A1, 2 and 3
B1 and 2 only
C1 and 3 only
D2 and 3 only
Mark scheme
45May / June 2016 · Paper 12 · Q39Show mark scheme →
Acombustion
Bcracking
Coxidation
Dreduction
Mark scheme