8 Ed-1

Air pollution

Name Class Date

1 Use the words in the word box to answer these questions.

carbon dioxide carbon monoxide soot (carbon) nitrogen oxides

sulfur dioxide water

a Name two substances produced when hydrocarbons burn fully in air.

b Name two other substances produced by the incomplete combustion of hydrocarbons.

c Name one substance that is produced from impurities in fossil fuels when they burn.

d Name one substance produced by a reaction of gases in air at the high temperature within
an engine.

2 Draw a line to link each pollutant with the problems it can cause.

poisonous, will kill if too much is

carbon dioxide
breathed in

acidic, dissolve in water droplets in

carbon monoxide
clouds and cause acid rain

probably causes global warming

soot particles
and climate change

coat the lining of the lungs when

sulfur dioxide and nitrogen oxides
breathed in and can trigger asthma

3 Complete the sentences to show how pollution from burning fossil fuels can be reduced.
a Acidic gases are removed from the chimney smoke of power stations and factories by

b Soot is removed from the exhaust of diesel vehicles by a

c In the catalytic converter on a car exhaust, carbon monoxide reacts with

to form .
d In a catalytic converter, nitrogen oxides are broken down to

I can…
● describe pollutants that are formed by burning products
● explain how these pollutants cause problems and how their effect can be reduced.

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 8 Ed-2
Measuring pollution

Your teacher may watch to see if you can:

● use a microscope carefully.

Aim
To compare particulate (e.g. soot) pollution in different areas.

Introduction
In this practical you will make sticky cards to collect particulate pollution from the air. You will put
the cards in different places and then analyse them to see how particulate pollution varies. Your
teacher will help you to decide where you will place your cards to collect particulate pollution.

Method
Apparatus
● square of acetate sheet printed with grid ● permanent marker
● double-sided sticky tape ● scissors
● plastic bag ● single-sided sticky tape
● drawing pins or sticky tape ● microscope slides
● microscope

Making the collector cards

A On a piece of plastic sheet, outline a 5  5 square on the grid using the marker pen.
B Cut a piece of double-sided sticky tape to fit over all of the marked square.
C Carefully stick the tape over the square, making sure the covering on the top of the tape is not
removed. When the top covering of the sticky tape is removed, this will be a collector card.
D Place the plastic sheet into a plastic bag to keep it clean until you are ready to collect a sample.
E Repeat steps A–D to make as many collector cards as your teacher has instructed.

Collecting the samples

F Decide where you are going to leave each collector card.
G Before you place a card, write in your name, the place, and date on the back of each card,
using the marker pen.
H Remove the cover on the top of the sticky tape. Be careful not to let the sticky surface touch
anything and do not touch it with your fingers.
I Use sticky tape or drawing pins to attach the card so that the sticky side is facing the air.
You must place the card somewhere where it is protected from rain.
J Repeat steps G–I for your other cards.
K Leave the cards in place for up to a week. They should all be left for the same time. When you
collect them, cover up the sticky surface with a piece of normal sticky tape right away.
L Record any details about each site, such as how near it is to roads, houses, factories or other
buildings.

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 8 Ed-3
Particle pollution sources

Your teacher may watch to see if you can:

● use a microscope carefully.

Aim
To compare particulate pollution in different areas.
Introduction
The soot particles formed when fossil fuels burn are too small to see without a microscope. You
can make sticky collector cards as described below. The cards can be left in different places to
collect particles. You then look at the cards under a microscope. You can work out the mean
number of particles per mm2 by counting the particles in several squares on the film.
Method
Apparatus
● square of acetate sheet printed with grid ● permanent marker
● double-sided sticky tape ● scissors
● plastic bag ● single-sided sticky tape
● drawing pins or sticky tape ● microscope slides
● microscope

Making the collector cards

A On a piece of plastic sheet, outline a 5  5 square on the grid using the marker pen.
B Cut a piece of double-sided sticky tape to fit over all of the marked square.
C Carefully stick the tape over the square, making sure the covering on the top of the tape is not
removed. When the top covering of the sticky tape is removed, this will be a collector card.
D Place the plastic sheet into a plastic bag to keep it clean until you are ready to collect a sample.
E Repeat steps A–D to make as many collector cards as your teacher has instructed.
Predicting
1 a Explain where you think the worst particulate pollution would be in your area?
Planning
2 a Where will you leave your sticky cards to test your hypothesis?
b How long will you leave them in place?
c Why have you chosen these locations and times?
3 Consider all the different variables that could affect the amount of particles collected at one site.
a List the possible variables, and say how each one could affect the results.
b Suggest how you could try to control each of these variables.
c If there are any variables you cannot control, suggest how you could reduce the possible
effects of these variables on your results.
4 When counting the specks, you should choose your squares at random. This means that there is
an equal chance of the choosing a square in any part of the grid. Doing this means that you do
not influence which parts of a grid are sampled. Suggest a way of picking squares at random.
5 How can you make your results as reliable as possible?
6 What safety precautions do you need to take while carrying out your investigation?

I can…
● compare the air pollution from different sites.

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 8 Ed-4
Acid rain

The cards show the different stages in the formation of acid rain and some of its effects.
1 Cut out the cards and arrange them on a piece of paper to form a flow chart. The shape of your
flow chart should be something like this:

2 Show your flow chart to your teacher and then stick the cards down.
3 Draw lines to join the cards.

I can…
● identify causes and effects of acid rain.

A B
Fish die in acidic lakes. Acidic gases dissolve in moisture in the air.

C D
Acid rain reacts with chemicals in the soil to Nitrogen oxides are produced by car engines.
release poisonous compounds.

E F
The dissolved gases make rain more acidic. Acid rain falls onto the land and runs into lakes
and rivers.

G H
Plants become unhealthy. Acid rain speeds up the weathering (breaking
down) of rocks.

I J
Burning fossil fuels, such as petrol and diesel, Acid rain washes some mineral salts out of the
produces carbon dioxide, sulfur dioxide and soil.
nitrogen oxides.

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 8 Ed-5
Pollution by non-metal oxides

Name Class Date

1 Circle the names of non-metal oxides in this list.

magnesium oxide sulfur dioxide carbon dioxide zinc oxide

2 The non-metal oxides in Question 1 are pollutants. What is a pollutant?

3 Name one source of these pollutants.

4 The graph shows the amount of sulfur dioxide gas released into the air in the UK each year
between 1970 and 2012.

a Complete the word equation to show how sulfur dioxide is formed.

+  sulfur dioxide
b Sulfur dioxide can cause acid rain. Why is acid rain a problem?

c Use the graph to help you describe why acid rain is much less of a problem in the UK now
compared with 30 years ago.

5 Carbon monoxide and soot particles are formed when there is incomplete combustion in a
car engine.
a What does incomplete combustion mean?

b Why is carbon monoxide a pollutant?

c Why is soot a pollutant?

I can…
● recall examples of pollution caused by burning fossil fuels
● interpret information about sulfur dioxide pollution.

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 8 Ed-6
Sources of air pollution

1 Most vehicles burn hydrocarbon fuels to release energy for movement.

a Write a word equation to describe the complete combustion of a hydrocarbon fuel.
b Name all the products of the incomplete combustion of a hydrocarbon fuel.
c Explain why incomplete combustion happens in a car engine.

2 Car engines are a source of several air pollutants.

a Sulfur dioxide is formed from sulfur impurities in the hydrocarbon fuel.
Write a word equation to show the formation of sulfur dioxide in a car engine.
b Nitrogen oxides are produced by the reaction of gases in the air at the temperature of the
engine. Write a word equation to show the formation of nitrogen oxides in a car engine.
c Explain why incomplete combustion of fuel is even more harmful to the environment than
complete combustion.

3 Sulfur dioxide and nitrogen oxides are pollutants because they can result in acid rain.
a Describe as fully as you can how acid rain is produced.
b Explain why acid rain is harmful.

The pie charts show the sources of emissions of three air pollutants measured in the UK in 2012.
Use these charts to help you answer Questions 4 and 5.

4 For which of the pollutants are vehicles the greatest source? Explain how you worked out this
answer from the pie charts.

5 Since December 2007 only ultra low-sulfur petrol and diesel have been sold in UK petrol
stations. Suggest how the road vehicles segment on the sulfur dioxide pie chart may have been
different before 2007, and explain your answer.

6 a What was the greatest source of sulfur dioxide in 2012?

b Use your answer to part a to suggest a method that would have the most impact in
reducing sulfur dioxide concentrations in the air.

7 All petrol cars made since 1992 have been fitted with a catalytic converter. Explain what effect
this has on each of the pollutants produced by these vehicles.

8 Suggest how pollution from road transport could be further reduced. Explain your answer.

I can…
● explain how fossil fuels produce pollutants when they are burnt.

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 8 Ed-7
Flue gas desulfurisation

The problem of sulfur in fossil fuels was well known in UK cities in the 19th century, because most
houses burnt coal for heating. Acidic sulfur dioxide gas, formed in the combustion of fossil fuels,
dissolves in water droplets in the air to make sulfuric acid. If these droplets are breathed in they
can damage the lungs. The problem got worse when the first power-generating stations were built
in the early 20th century in cities to provide electricity. Thick yellow ‘smogs’ (a combination of fog
and smoke) were common and caused many deaths from breathing problems.

The first flue gas desulfurisation (FGD) unit was added to Battersea Power Station in London in
1931, to remove sulfur dioxide from the gases given off by burning coal before they were released
into the air. This unit passed the gases through water to dissolve the sulfur dioxide. The liquid
produced was released into the river.
Due to improvements in transmitting electricity over long distances, later power stations were built
further from cities. FGD units were not added because of their cost.
European targets for reducing sulfur dioxide emissions were introduced in 1985, and were revised
to lower levels in 1994, 1999 and 2012. These require countries of the European Union to find
ways to reduce sulfur dioxide emissions to keep within the limits. So, FGD units have been added
to power stations once again.
The most common method of FGD is a ʻwet treatmentʼ that sprays an alkaline mixture of calcium
carbonate and water through the flue gases. The sulfur dioxide reacts with the mixture to produce
calcium sulfate (known as gypsum), and this can be used to make wallboards or cement. This
method removes about 90% of the sulfur dioxide, but the units are expensive to build and run.
The units are too expensive for smaller power plants or industries. One alternative uses dry
powdered calcium carbonate to capture the sulfur dioxide, but this captures only about 75% of the
gas. Another alternative is to burn low-sulfur fuels such as natural gas.
1 Write a word equation and symbol equation for the formation of sulfur dioxide from sulfur in
fossil fuels.
2 The release of liquid from the flue desulfurisation unit into the river from Battersea Power
Station was stopped because of its impact on the river. Suggest what impact it was having and
explain your answer.
3 a Suggest why there was less concern about sulfur dioxide gases released from power
stations far from cities than from those built within cities.
b Using what you know about acid rain formation, explain the problems with this point of view.
4 Electricity-generating stations are also a major source of nitrogen oxides. Suggest how these
emissions of nitrogen oxides could be reduced.
5 Sulfur dioxide, nitrogen oxides, carbon dioxide and water vapour are all transparent gases.
Explain why the chimney smoke from a power station looks ‘smoky’, and suggest what could
be done to reduce this pollution.
6 Compare the wet and dry desulfurisation treatments that use calcium carbonate.
7 Explain why different kinds of desulfurisation treatment are needed for different kinds of power
plants and industries.

I can…
● evaluate the use of flue gas desulfurisation to reduce sulfur dioxide pollution.

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