4.9.3.2Properties and effects of atmospheric pollutants
AQA GCSE Chemistry Foundation (8462), Foundation tier · Chemistry of the atmosphere › Common atmospheric pollutants
Practise Properties and effects of atmospheric pollutants. 7 exam-style questions on this subtopic, at up to four difficulty levels, with full mark schemes and a progress tracker. Free, no account needed.
The problems caused by carbon monoxide, sulfur dioxide, oxides of nitrogen and particulates in the air. Expect 1 to 3 mark 'give' and 'explain' questions, data questions on pollution levels, and 6-mark answers that link each pollutant to how it forms and the problems it causes.
Key facts
Carbon monoxide: toxic, colourless and odourless, so not easily detected
Sulfur dioxide and oxides of nitrogen: respiratory problems and acid rain
Acid rain: damages buildings and statues, harms trees and plants, acidifies lakes (kills aquatic life)
Particulates: global dimming and health problems (lung damage)
Global dimming: particulates reflect sunlight, so less reaches the Earth's surface
Notes
Carbon monoxide
Carbon monoxide, CO, is a toxic gas.
It is colourless and odourless, so it is not easily detected. People can be poisoned without knowing, which is why homes with fuel-burning boilers, fires or stoves should have carbon monoxide alarms.
Sulfur dioxide and oxides of nitrogen
diagram
Both cause respiratory problems in humans, e.g. breathing difficulties, and can make asthma worse.
Both cause acid rain: they dissolve in water droplets in clouds to form acidic solutions, which fall as rain.
Sulfur dioxide and oxides of nitrogen cause acid rain far from where they are released.
Acid rain damages buildings and statues, especially those made of limestone, which reacts with acids. It also corrodes metals.
Acid rain damages trees and other plants, and makes lakes and rivers more acidic, which can kill fish and other aquatic life.
Particulates
Particulates are tiny solid particles, such as soot, and unburned hydrocarbons in the air.
They cause global dimming: they reflect sunlight back into space, so less sunlight reaches the Earth's surface.
They cause health problems: very small particles can be breathed deep into the lungs, damaging them and causing breathing problems.
Linking source to effect
Carbon monoxide: from incomplete combustion; toxic and hard to detect.
Sulfur dioxide: from sulfur in the fuel; acid rain and respiratory problems.
Oxides of nitrogen: from nitrogen and oxygen in the air at high temperature; acid rain and respiratory problems.
Particulates: from incomplete combustion and unburned fuel; global dimming and health problems.
How to answer each type of question
Recall a property or effect of a pollutant
1 to 3 marksGrade 4
Match the pollutant to its problem: CO toxic; SO2 and NOx acid rain and breathing problems; particulates global dimming and health problems.
Give the specific property asked for, e.g. 'colourless' or 'odourless'.
Example. (a) Give one property of carbon monoxide that makes it difficult to detect. (b) Name two pollutants that cause acid rain.
Say the gas dissolves in water in clouds to form acid rain.
Name what is damaged: buildings and statues, trees and plants, lakes and aquatic life.
Say how, e.g. the acid reacts with limestone.
Example. A coal-burning power station releases sulfur dioxide. Describe how this can damage a forest and a limestone building many kilometres away.
Show the model answerHide the model answer
The sulfur dioxide is carried by the wind and dissolves in water droplets in clouds (1), forming acid rain (1). The acid rain damages or kills the trees (1) and reacts with the limestone, wearing away the building (1).
Don’t lose marks
Saying carbon monoxide causes acid rain or global warming. Its problem is that it is toxic.
Saying carbon dioxide causes acid rain. Acid rain is caused by sulfur dioxide and oxides of nitrogen.
Confusing global dimming (particulates reflect sunlight) with global warming (greenhouse gases absorb long wavelength radiation).
Writing vague effects such as 'harms the environment'. Name what is damaged: buildings, trees, lakes, fish.
Saying you can smell carbon monoxide. It is odourless.
More tips
Memory tricks
Carbon monoxide is the 'silent killer': no colour, no smell.
Acid rain gases are the 'S and N' pair: sulfur dioxide and nitrogen oxides.
Particulates: 'Dim and Damage': global dimming and damage to lungs.
Learn one problem per pollutant first, then add the detail (why or how).
Exam technique
Link each pollutant to its specific problem: 'causes pollution' does not score.
For carbon monoxide, 'toxic' is one mark and 'colourless and odourless, so not easily detected' is another.
In 6-mark pollutant answers, organise by pollutant: how it forms, then the problems it causes.
Show your working for percentage change: change ÷ original × 100.
What each grade needs
What you need to be able to do, from the first marks up to the top grade.
Grade 3
State that carbon monoxide is toxicCarbon monoxide is a toxic (poisonous) gas.
Grade 4
Name the gases that cause acid rainSulfur dioxide and oxides of nitrogen cause acid rain.
Grade 4
Give effects of acid rainIt damages buildings and statues, harms trees and plants, and makes lakes acidic, harming aquatic life.
Grade 5
Explain why carbon monoxide is hard to detectIt is colourless and odourless, so you cannot see or smell it.
Sample questions
Written for this site in the style of AQA exam questions. They are not taken from real past papers.
Question 1Easy4 marks
(a) Which pollutant causes global dimming? Tick (✓) one box.[1]
Carbon monoxide
Particulates
Sulfur dioxide
Water vapour
(b) Why is carbon monoxide difficult to detect?[1]
(c) Name two pollutants that cause acid rain.[2]
Show the answer and mark scheme
(a)Answer: Particulates
(b)
it is colourless and odourless
(c)
sulfur dioxide
oxides of nitrogen / nitrogen dioxide
Question 2Medium5 marks
People are advised to fit carbon monoxide detectors in homes that have gas boilers.
(a) Explain why carbon monoxide is dangerous.[2]
(b) Suggest how a faulty gas boiler could produce carbon monoxide.[1]
(c) Particulates are another pollutant from burning fuels. Describe the problems caused by particulates.[2]
Show the answer and mark scheme
(a)
it is toxic / poisonous
it is colourless and odourless so it is not easily detected
(b)
not enough air / oxygen reaches the flame so the gas undergoes incomplete combustion
(c)
global dimming (they reflect sunlight, so less reaches the Earth’s surface)
health problems for humans (e.g. damage to the lungs when breathed in)