Diffusion
1.2What the syllabus asks of you
- Describe and explain diffusion in terms of kinetic particle theory
- Describe and explain the effect of relative molecular mass on the rate of diffusion of gases
Read the notes first
Chapter 1: Diffusion
Drill this topic
Every question on Diffusion, untimed, marked as you go.
Make a worksheet
Choose the years and how many questions, then print it with the answers on separate pages.
21 questions
1May / June 2026 · Paper 12 · Q1Show mark scheme →
Aammonia
Bhydrogen sulfide
Cpropane
Dxenon
Mark scheme
2Oct / Nov 2025 · Paper 11 · Q2Also set in May / June 2018 Paper 11Show mark scheme →
Acarbon dioxide at 0 °C
Bcarbon dioxide at 25 °C
Cneon at 0 °C
Dneon at 25 °C
Mark scheme
3May / June 2025 · Paper 11 · Q1Show mark scheme →
A1 2 4 3
B2 1 3 4
C3 4 2 1
D4 1 3 2
Mark scheme
4May / June 2025 · Paper 12 · Q2Show mark scheme →
Acondensation
Bdiffusion
Cdissolving
Devaporation
Mark scheme
5Oct / Nov 2024 · Paper 11 · Q2Show mark scheme →
Aammonia, NH3
Bcarbon monoxide, CO
Cethane, C2H6
Doxygen, O2
Mark scheme
6Oct / Nov 2024 · Paper 12 · Q1Show mark scheme →
AArgon and helium atoms become evenly mixed throughout the container even though they have different masses.
BArgon and helium atoms both move towards the bottom of the container. The argon atoms settle more quickly because they are larger and heavier.
CArgon and helium atoms both move towards the bottom of the container. The helium atoms settle more quickly because they are smaller and lighter.
DArgon atoms move to the bottom of the container because they are heavier. Helium atoms move to the top of the container because they are lighter.
Mark scheme
7Oct / Nov 2023 · Paper 11 · Q2Show mark scheme →
AH₂S; gases diffuse faster than liquids
BH₂S; H₂S has a lower Mᵣ than PCl₃
CPCl₃; gases diffuse faster than liquids
DPCl₃; PCl₃ has a lower Mᵣ than H₂S
Mark scheme
8Oct / Nov 2023 · Paper 12 · Q2Show mark scheme →
A1, 2 and 4
B2 and 3
C3 only
D4 only
Mark scheme
9Oct / Nov 2022 · Paper 11 · Q4Show mark scheme →
Anitrogen at 25 °C
Bnitrogen at 50 °C
Coxygen at 25 °C
Doxygen at 50 °C
Mark scheme
10May / June 2022 · Paper 12 · Q5Also set in May / June 2022 Paper 11Show mark scheme →
AA
BB
CC
DD
Mark scheme
11Oct / Nov 2021 · Paper 11 · Q7Show mark scheme →
Acarbon dioxide — high
Bcarbon dioxide — low
Cmethane — high
Dmethane — low
Mark scheme
12Oct / Nov 2021 · Paper 12 · Q7Show mark scheme →
ASF6, 20 °C
BSF6, 40 °C
CCO2, 20 °C
DCO2, 40 °C
Mark scheme
13May / June 2020 · Paper 12 · Q6Show mark scheme →
Ahydrogen chloride at –40 °C
Bhydrogen chloride at –20 °C
Chydrogen sulfide at –40 °C
Dhydrogen sulfide at –20 °C
Mark scheme
14May / June 2019 · Paper 11 · Q4Show mark scheme →
Alarge; high
Blarge; low
Csmall; high
Dsmall; low
Mark scheme
15May / June 2019 · Paper 12 · Q4Show mark scheme →
AAr
BC$_3$H$_8$
CCO$_2$
DF$_2$
Mark scheme
16May / June 2018 · Paper 12 · Q4Show mark scheme →
A1, 2 and 3
B1 and 2 only
C1 only
D2 and 3 only
Mark scheme
17Oct / Nov 2017 · Paper 11 · Q1Show mark scheme →
ADiffusion occurs because the pill is coloured.
BDiffusion occurs faster at higher temperatures.
CDiffusion occurs from an area of high concentration to one of lower concentration.
DGases diffuse faster than liquids.
Mark scheme
18May / June 2017 · Paper 11 · Q8Show mark scheme →
AChlorine has a relative molecular mass of 71 whilst neon has a relative atomic mass of 20.
BChlorine is at a higher temperature than neon.
CChlorine is diatomic and neon is monatomic.
DChlorine is more reactive than neon.
Mark scheme
19Oct / Nov 2016 · Paper 11 · Q9Show mark scheme →
A1 2 4 3
B2 1 3 4
C3 4 2 1
D4 1 3 2
Mark scheme
20Oct / Nov 2016 · Paper 12 · Q1Show mark scheme →
Aammonia, NH3
Bcarbon monoxide, CO
Cethane, C2H6
Doxygen, O2
Mark scheme
21May / June 2016 · Paper 12 · Q11Also set in May / June 2016 Paper 11Show mark scheme →
ANitrogen is almost inert.
BThe two gases have equal molecular masses.
CBoth gases have two atoms in a molecule.
DNeither gas is soluble in water.
Mark scheme