8 Ea-1

Burning fuels

Name Class Date

Answer the questions below on combustion. Cut out the cards at the bottom of the sheet to help
you answer Questions 4 and 6.

1 What does combustion mean?

the process of burning something The reaction of a fuel with oxygen to release useful energy

2 When hydrogen burns in air, which gas does it react with?

Remember:
Oxygen Air is a mixture of
gases, including
nitrogen, oxygen and
3 What product is formed when hydrogen burns in air? hydrogen oxide carbon dioxide.
(water)
4 Stick the correct cards in the spaces below to model the combustion of hydrogen in air.

Hydrogen + Oxygen  Water

5 Use your word equation above to:

a name a reactant in the reaction Hydrogen

b name a product in the reaction Hydrogen Oxide (water)

6 Stick the correct cards in the spaces below to model the reaction between carbon and oxygen.

Carbon + Oxygen  Carbon Dioxide

7 What is a hydrocarbon?
A substance that only contains Hydrogen and Carbon.

8 Write a word equation that models the combustion of a hydrocarbon in air.

Hydrocarbon + Oxygen → Carbon dioxide + Water

I can…
● identify reactants and products in combustion reactions
● model combustion reactions using word equations.

hydrogen carbon dioxide water

carbon oxygen oxygen

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 8 Ea-2
Burning a fuel

Name Class Date

Your teacher will set up this apparatus and light the spirit lamp, which contains a hydrocarbon fuel.
(Note: it is the fuel that is burning, not the wick.)

Use your observations of what happens to answer the questions below.

1 Why is the suction pump needed?

To force the products of the reaction of burnt fuel ( CO2 and Water) to pass through the blue cobalt chloride paper

(which tests the presence of water) and the limewater ( which tests the presence of CO2)
2 What happens to the temperature measured on the thermometer?
The temperature increases

3 What happens to the blue cobalt chloride paper and why does this happen?
It changes to pink in the presence of Water.

4 What happens to the limewater and why does this happen?

The limewater turns cloudy because carbon dioxide is present

5 Use your answers to Questions 3 and 4 to write a word equation for the combustion of the fuel.
Fuel + Oxygen → Carbon dioxide + Water

6 Which two observations are evidence that the combustion of fuel releases energy?
Explain your answer.
1) The light energy that has been released from the flame
2) The cloudness of limewater 3) the release of heat energy

I can…
● identify the products from the combustion of a hydrocarbon
● use word equations to model the combustion of a fuel.

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 8 Ea-3
Combustion questions

Name Class Date

1 Use one word from the box below to complete each of these sentences. (Note: some of the
words will not be used.)

a Another name for burning is Combustion .

b Fuels formed by living organisms that died millions of years ago are called
fossil fuels.
c A substance that contains only hydrogen and carbon is called a hydrocarbon .

combustion explosion fossil hydrocarbon hydrogen

2 This word equation models the combustion reaction between hydrogen and oxygen.
hydrogen + oxygen  water

a Is oxygen a reactant or product of this reaction? reactant .

b Is water a reactant or product of this reaction? product .

3 Complete this word equation to model the combustion reaction of carbon and oxygen:

carbon + oxygen  Carbon Dioxide .

4 The diagram shows equipment used to test what is produced when the fuel in a spirit lamp
is burnt.

a What does the cobalt chloride paper test for? the presence of water .

b What does the limewater test for? the presence of carbon dioxide
.
c How will the thermometer reading change during the experiment?
It will increase
d Explain why the thermometer reading changes in this way.
This is because when combustion occurs heat energy is released making the

temperature increase.

I can…
● identify reactants and products in combustion reactions
● describe how the products of combustion reactions can be tested for.

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 8 Ea-4
Methane explosion

Name Class Date

In January 2014, a cow shed in Germany exploded, causing flames that damaged the roof and
injured one of the cows. The 90 cows had been living in the shed during the winter.
A cow may produce up to 500 dm3 of methane each day from the digestion of its food. Police
suspected that the explosion was caused by combustion of the methane.

1 a What is meant by ‘combustion’? The reaction of a fuel with oxygen to release useful energy

b Methane is a hydrocarbon. What does this mean? Methane is a Hydrocarbon because it is only
made up of hydrogen and carbon.
c What did the methane react with during the explosion? Oxygen
d Which two products would have been formed in this reaction? Carbon dioxide and water

e Describe tests that could be used to identify the two products. (Remember to describe all
that happens in each test.)

f Write a word equation for the combustion reaction of methane.

g What else was released in this reaction? Explain your answer.

h Police investigating the accident found no open flame that could have caused the explosion.
Instead they suggested that there must have been a spark, such as from static electricity.
Explain why the police thought a spark or flame must have started the reaction.

2 Methane is a fuel that is used in some kinds of car engines. Explain why methane is a fuel.
because it releases energy
3 Hydrogen is another fuel that can be used in vehicles. In some kinds of engines the hydrogen
is combusted, as with methane. Other vehicles have hydrogen fuel cells. Describe what
happens in a hydrogen fuel cell.

The source of hydrogen is generally referred to as the fuel and this gives the fuel cell
its name, although there is no combustion involved. Oxidation of the hydrogen instead
takes place electrochemically in a very efficient way. During oxidation, hydrogen atoms react
with oxygen atoms to form water; in the process electrons are released and flow through an external
circuit as an electric current.

I can…
● describe the combustion of hydrocarbons
● use word equations to model combustion reactions.

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 8 Ea-5
Combustion engines

Most car engines have an internal

combustion engine that contains four
pistons, each in a separate cylinder. At the
top of each chamber are two valves. One
valve lets substances into the cylinder and
the other lets exhaust gases out. The
pistons are connected together by a
rotating crankshaft, which also transfers
movement to the wheels.
The four pistons go through the same four
ʻstrokesʼ of the cycle, but at different times.
● 1st stroke/intake: The piston is pulled
down as the crankshaft turns. This
creates a vacuum in the cylinder, which
draws a fuel/air mixture in through the
inlet valve.
● 2nd stroke/compression: The piston is pushed up again by the rotating crankshaft. This
compresses (squashes) the fuel/air mixture at the top of the cylinder, as both valves are closed.
● 3rd stroke/power: A spark at the top of the cylinder ignites the fuel/air mixture. The very hot
gases produced expand rapidly, pushing the piston to the bottom of the cylinder. The linear
movement of the piston is converted to circular movement by the shape of the crankshaft.
● 4th stroke/exhaust: The piston is pushed back up the cylinder by the crankshaft, and the gases are
pushed out of the outlet valve. This sets the piston in the right position to start the cycle again.
Use the information above and your own knowledge to answer these questions.
1 a A steam engine is an external combustion engine. Explain why a car engine is called an
ʻinternal combustionʼ engine.
b Briefly compare this kind of engine with how a steam engine works.
2 Suggest why modern cars have this kind of engine and not steam engines. Give as many
reasons as you can.
3 Explain how a force is generated in the power stroke.
4 The movement of the crankshaft also drives a fan that blows air across the engine. Suggest
why the fan is needed. So that the engine does not overheat
5 There are many reasons why an internal combustion engine may not work properly. For each
of the following reasons, explain why the engine will not be effective.
a The car has run out of fuel. Fuel is essential for combustion to produce energy.
b The spark fails or is weak. The combustion reaction might not be initiated
c There is water in the fuel.
d The sealing rings around the pistons or valves are broken and let air into the cylinder.
Space rockets use a different kind of internal
combustion engine, as shown on the right.
(Note: an oxidising agent releases oxygen.)
6 Explain why the space rocket engine differs
from a car engine. Suggest as many
reasons as you can for the differences.
The main difference between them is that jets get the oxygen to
burn fuel from the air and rockets carry their own oxygen, which
allows them to operate in space. Jet engines have two openings
(an intake and an exhaust nozzle). Rocket engines only have one opening
(an exhaust nozzle).

I can…
● use knowledge of combustion to explain how combustion engines work.

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 8 Eb-1
Oxidation

Name Class Date

1 Hydrogen and oxygen react to form water.

a Colour the oxygen atoms in red. Colour the hydrogen atoms in grey.

a How many hydrogen atoms are there in all the reactants? 4

b How many hydrogen atoms are there in all the products? 4

c How many oxygen atoms are there in all the reactants? 2

d How many oxygen atoms are there in all the products? 2

e If the masses of oxygen and hydrogen were measured before the reaction, and the mass
of water formed was measured after the reaction, what would we see?
Tick () the correct box.

 total mass of hydrogen and oxygen greater than mass of water

 total mass of hydrogen and oxygen same as mass of water

 total mass of hydrogen and oxygen less than mass of water

2 When a metal reacts with oxygen, the metal oxide is formed. Write down the products of these
reactions.

a magnesium + oxygen  Magnesium oxide

b copper + oxygen  copper oxide

c What is the name of this kind of reaction? oxidation

3 Sometimes it seems as if mass has been gained in a reaction.

The zinc has combined with oxygen to form zinc oxide.

Where did the oxygen come from? The oxgygen came from the air

I can…
● state what happens to mass in an oxidation reaction
● describe oxidation reactions of metals.

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 8 Eb-2
Changing mass

Your teacher may watch to see if you can:

● follow instructions carefully
● work safely.

Aim
To measure the change in mass when magnesium is burnt in air.

Introduction
When magnesium burns in air, it reacts with oxygen to form magnesium oxide.

Method
Apparatus Eye protection should be worn. Use
● magnesium ribbon ● tongs tongs to handle apparatus, as it will
take time to cool down after heating.
● pipe clay triangle ● crucible with lid Do not look directly at burning
● Bunsen burner ● tripod magnesium.
● access to balance ● emery paper
● heat-resistant mat

A If the magnesium looks dull or black, rub it with emery paper until it is shiny.
B Measure the mass of the crucible and lid to two decimal places. Record the mass in the table
on the next page.
C Twist the magnesium ribbon into a loose coil and place it in the crucible. Measure the mass
of the crucible, lid and magnesium accurately. Record the mass.
D Set up the apparatus as shown in the diagram. Make sure that the crucible is held securely
and that the lid is fully on.
E Light the Bunsen burner and, using a roaring flame, heat the crucible.
F Once the magnesium starts to burn, use the tongs to slightly lift the lid to let in air. Don’t allow
the flame from the magnesium to escape, as this may allow some magnesium oxide to
escape.
G Keep heating and lifting the lid until there is no further reaction. Use the tongs to remove the
crucible lid and place it on the heat-resistant mat. Continue heating for another two minutes.
H Turn the Bunsen burner off and allow everything to cool.
I Measure the mass of the crucible, lid and product.

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 8 Eb-2
Changing mass

Name Class Date

Results table
1 Complete this table of results.

Mass (g)

mass 1 crucible + lid

mass 2 magnesium + crucible + lid

mass 3 product + crucible + lid

Considering your results/Conclusions

2 Calculate the mass of magnesium by subtracting mass 1 from mass 2.

mass of magnesium = – = g

3 Calculate the mass of magnesium oxide by subtracting mass 1 from mass 3.

mass of magnesium oxide = – = g

4 Describe the difference in mass between the magnesium and the magnesium oxide.
Magnesium oxide is heavier than magnesium

5 Explain the difference in mass between the magnesium and the magnesium oxide.
this is because the magnesium reacted with the oxygen forming a new compound which is magnesium
oxide.
6 Calculate the mass of oxygen that reacted with the magnesium. Show your working in the
space below.

7 Describe how the experiment could be improved to get more accurate results. Explain your
answer.
Repeat the experiment to obtain an average

I can…
● state what happens to mass in a chemical reaction
● explain the change in mass seen in reactions.

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 8 Eb-3
Phlogiston

In 1703, George Stahl, a German scientist, published his theory of phlogiston. This theory was
used for nearly a century to explain what happened in combustion reactions. The careful
experiments of Antoine Lavoisier and Joseph Priestley in the 1770s showed that combustion was a
reaction with oxygen. Today, we describe any reaction in which a substance combines with oxygen
as ‘oxidation’. Combustion is a type of oxidation in which a lot of energy is transferred that we can
see and feel.
Cut out the cards below and divide them into two groups; those that are about the phlogiston
theory and those that are about our modern theory of oxidation.
Then use the information to help you answer these questions.

1 Stahl developed his theory by observing the burning of wood.

a Write a word equation for the combustion of wood to form ash using the phlogiston theory.
b Write a word equation for the combustion of wood to form ash using the oxygen theory.
c The wood ash that is left after the combustion of wood has a smaller mass than the wood
that was burnt. Compare how the two theories would explain this change in mass.

2 Metals also change when they are heated strongly in air.

a Write a word equation for this reaction using the phlogiston theory.
b Write a word equation for this reaction using the oxidation theory.
c When a metal is heated strongly in air, the substance formed has a greater mass than the
metal that was used. Compare how the two theories would explain this change in mass and
describe one piece of evidence that shows us that the oxidation theory is correct.

I can…
● contrast the theories of oxygen and phlogiston in combustion
● evaluate the evidence used to displace the phlogiston theory of combustion.

Anything that burns contains During combustion, the The gain in mass of a metal
phlogiston. substance reacts with oxygen. when it is heated in air is the
mass of the oxygen it reacts
with.
The oxygen in a combustion Combustion releases the Metals heated strongly in air
reaction comes from the air or phlogiston into the air leaving also release phlogiston,
another substance (an a solid calx. leaving the metal calx.
oxidising agent).
The more phlogiston a Air is needed for combustion
substance contains, the more because it absorbs the
completely it burns. phlogiston – it becomes
phlogisticated air.

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 8 Eb-4
Metal reactions

Name Class Date

1 The diagram shows magnesium ribbon that has been heated strongly in air. What evidence in
this diagram shows that a reaction is happening? Tick () the correct box.

 The magnesium is changing colour.

 The very bright flame shows that energy is released.
 The magnesium gets hotter.
2 What kind of reaction is shown happening in the diagram? Circle the correct answer.

neutralisation oxidation revision

3 Which gas in air does the magnesium react with? Tick () one box.

 carbon dioxide
 nitrogen
 oxygen
4 Write a word equation to model what happens in the reaction shown above.
Magnesium + oxygen  magnesium oxide

5 When copper metal reacts with oxygen, copper oxide is formed. Write a word equation for this
reaction.
copper + oxygen → copper oxide

6 If the mass of copper and the mass of oxygen were measured before the reaction, what would
be the mass of copper oxide formed? Tick () one box.

 The same as the mass of copper added to the mass of oxygen.

 More than the mass of copper added to the mass of oxygen.
 Less than the mass of copper added to the mass of oxygen.

I can…
● describe oxidation reactions of metals
● state what happens to mass in a chemical reaction.

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 8 Eb-5
Mass in reactions

1 A magnesium flare is a bright light produced when magnesium metal burns in air. It has several
military uses. Magnesium flares may be dropped at night to illuminate a landing area for
paratroopers. They may also be launched from planes or helicopters as decoys, to attract
heat-seeking missiles that usually target hot engines.

a Which gas in air does the magnesium in the flare react with? oxygen
b What kind of reaction is happening when magnesium reacts with this gas? oxidation
c What is the evidence that the magnesium is reacting? Explain your answer.
d Write word equations for the reaction of each of these metals with the gas.
magnesium + oxygen → magnesium oxide
lead + oxgen → lead oxide
potassium + oxygen → potassium oxide
2 When zinc powder is heated strongly in air a white ash is formed.
a What is the white ash? Zinc oxide
b How does the mass of the ash compare with the mass of the zinc powder before the
reaction? The mass increases
c Explain your answer to part b.
3 The table shows the mass of a spirit burner
and the hydrocarbon fuel it contains during a
20-minute period after the burner was lit.

Time (min) 0 5 10 15 20

Mass of burner 182.3 181.8 181.2 180.7 180.2

+ fuel

a Describe what the results show.

b Explain why the results show this pattern.

I can…
● identify the changes that occur when metals are heated strongly
● explain changes in mass seen in oxidation reactions.

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 8 Eb-6
Formula equations

The word equation for the reaction of carbon with oxygen is:
carbon + oxygen  carbon dioxide
We can also write this equation using the chemical formula for each substance:
C + O2  CO2
Carbon dioxide exists as molecules and its formula shows the number of the different atoms in the
molecule. If there is no little number after a symbol, there is only one atom. Otherwise the little
number tells you how many atoms of that type are in the molecule. Oxygen is an element but
exists as ‘diatomic’ molecules – two atoms of the same kind joined together. Carbon does not exist
as molecules but as a huge structure of billions of carbon atoms joined together. We have no idea
how many so we just write the symbol for the element.
1 How many carbon atoms and how many oxygen atoms are there in one molecule of carbon
dioxide? 1 carbon atom and 2 oxygen atoms
2 Look at the chemical equation above. Count the number of carbon atoms and oxygen atoms in
the products and in the reactants.
a What do you find? They are the same
b How does this explain the law of conservation of mass in reactions?
Hydrogen usually reacts with oxygen to produce water, but in special conditions it can form
another molecule called hydrogen peroxide. The formula for hydrogen peroxide is H2O2.
3 Write a word equation and then a symbol equation to model the formation of hydrogen peroxide
from hydrogen gas and oxygen gas. (Hint: hydrogen gas is a diatomic molecule.)
Check your formula equation by counting the number of atoms on each side.
The formula for a substance never changes. Oxygen gas is always O2, hydrogen peroxide is
always H2O2, and magnesium oxide is always MgO. However, writing the symbol equation for the
formation of magnesium oxide isn’t as straightforward as for carbon dioxide and hydrogen
peroxide.
If we start with the standard formula for each substance we get:
Mg + O2  MgO
Counting the number of atoms on each side, there is one magnesium atom on each side, which is
what we would expect. But there are two atoms of oxygen on the left side and only one on the
right, which isn’t correct. We could write Mg + O  MgO, but this is wrong because oxygen is a
diatomic molecule.
We need another way to ‘balance’ the atoms on each side. We do this by multiplying the quantities
by the smallest number needed to make the atoms balance. We need two oxygen atoms on the
right as well as the left side of the equation, so multiply the magnesium oxide formula by 2:
Mg + O2  2MgO
The problem now is that we have two magnesium atoms on the right but only one on the left, so
we multiply the magnesium on the left by 2. The simplest answer to this is:
2Mg + O2  2MgO
Now the number of atoms on each side of the equation is the same – and the equation is
balanced.
4 Try writing balanced symbol equations for the following reactions.
a Sulfur reacts with oxygen to produce sulfur dioxide. S + O2 → SO2
b Zinc reacts with oxygen to produce zinc oxide (ZnO). 2Zn + O2 → 2ZnO
c Hydrogen gas reacts with oxygen gas to form water. 2H2 + O2 → 2H2O

I can…
● write simple balanced symbol equations.

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 8 Eb-7
Ideas old and new

Scientists used the phlogiston theory to explain some of their observations. Now that we no longer
believe that phlogiston exists we must be able to explain the observations in a different way.

1 Explain each idea in the boxes in modern terms. If you can, give the modern names for the
substances mentioned. Try to write word equations to help your explanations. The first one has
been done for you. (Hint: a ‘calx’ is usually an oxide. Some oxides decompose when you heat
them.)

2 Write a symbol equation for the reaction in box 1.

3 Use the information in the boxes to evaluate the phlogiston theory. Identify its good points
(where it can explain the observation) and its weak points.

4 Write a sentence to explain why scientists no longer believe the theory.

I can…
● explain and compare the oxygen and phlogiston theories for combustion and oxidation.

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 8 Ec-1
The fire triangle

Name Class Date

Cut out each of the boxes and stick them in the correct places on the fire triangle.

the gas in the air that a water extinguisher cools

is needed for things to burn fire and takes this away

taken away if you smother energy needed to start a

a fire with a fire blanket fire

a substance that contains cutting down trees in a

a store of energy forest fire takes this away

I can…
● use the fire triangle to explain how to control a fire.

the gas in the air that is a substance that contains a

energy needed to start a fire
needed for things to burn store of energy

a water extinguisher cools the taken away if you smother a cutting down trees in a forest
fire and takes this away fire with a fire blanket fire takes this away

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 8 Ec-2
Candle height

Your teacher may watch to see if you can:

● follow instructions to carry out a fair test.

Aim
To investigate the effect of candle flame height (inside a container) on the length of time it takes to
go out.

Introduction
Candles are made from a hydrocarbon wax. There are many variables that could affect the time it
takes the candle flame to go out. To carry out a fair test, where only the height of the candle affects
the time, all other variables must be controlled.
1 Look at the apparatus in the box.
a Which variables, apart from the height of the block on which the candle stands, could vary
in a way that affects the time that the candle flame burns for? the height and volume of the
container
b What could be done to control these variables, so that they don’t affect the time?

use the exact same containers

Method
Apparatus Open flames can cause fires.
● 2 tea lights ● 2 heat-resistant glass containers Tie long hair back and keep
loose clothing away from
● stopwatch ● ruler flames. Allow the glass
● wax taper ● 2 heat-resistant mats containers to cool before
● modelling clay ● small block touching them.

A If the glass containers have a pouring lip, block the lip with a small piece of modelling clay to
prevent air from entering when the containers are placed top-down on the bench.
B Place one tea light on a heat-resistant mat. Place the other tea light on the block on a
heat-resistant mat.
C Measure the height of the base of the wick of both lights from the mat and record the values.
D Use a lit wax taper to light both lights. Cover both lights at the same time with the glass
containers and start the stopwatch.
E Measure the time taken for each flame to go out and record the values.

Considering your results/Conclusions

2 What do your results show about the effect of height of candle on the time taken for the flame
to go out? The taller the candle the less time it takes for the fire to go out
3 Suggest a reason why height had this effect. because potential space for oxygen is taken up

Evaluation
4 Explain why you can be sure that this effect was caused by the height of the flame and not
something else. because the height of the candle is the only thing that changed in this experiment

I can…
● identify variables in an experiment that need to be controlled and how to control them.

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 8 Ec-3
Comparing fuels

Your teacher may watch to see if you can:

● follow instructions to safely carry out an investigation.

Aim
To plan and carry out an investigation to show which
fuel releases the most energy during combustion.
Introduction
There are many kinds of fuel that can be burnt to
release energy for heating. These include solid fuels
such as coal, liquid fuels such as petrol and ethanol,
and gas fuels such as hydrogen and methane. Some
fuels release more energy than others during
combustion.
You will plan an investigation to find out which of four
liquid fuels releases the most energy, using the
apparatus shown. The fuel in the burner combusts in air
to release energy that heats the water in the beaker.

Method
Apparatus Wear eye protection. Tie
● 4 spirit burners containing fuels A–D hair back and keep the
heating area clear. Spirit
● balance ● beaker ● stopclock
burners must be kept
● tripod ● gauze ● heat-resistant mat upright. All fuels are highly
● thermometer ● water ● wax taper flammable.

Planning
1 In this investigation, what is the independent variable and what is the dependent variable?
The fuel which fuel releases the most energy
2 Explain how the dependent variable is related to the energy released during combustion of
the fuel.
3 Other variables in the experiment include:
i mass of water iv time that fuel is allowed to burn
ii volume of beaker v height of beaker above flame.
iii mass of fuel
For each variable, consider:
a how it might affect the results
b whether it needs to be controlled
c how it could be controlled.
4 Suggest any other variables that might affect the results, and how they should be controlled.
5 Use the answers to the questions above to help you plan your investigation. Show your plan to
your teacher before you start your investigation.
6 Record your results in a table and use them to draw a chart.
7 Draw a conclusion from your results.
8 Evaluate your results and suggest how the experiment could be improved to give better results.

I can…
● plan and carry out an experiment to compare the energy released by burning fuels.

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 8 Ec-4
Fire extinguishers

1 Colour in the fire extinguishers, making sure the band is the correct colour for the type of
extinguisher.

2 Cut out the cards.

3 Your teacher will describe some kinds of fire. Select an extinguisher that will put each fire out
quickly and safely. (Note: there may be more than one kind of extinguisher that will work on
some kinds of fire.)

Water Carbon dioxide Powder Foam

extinguisher extinguisher extinguisher extinguisher

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 8 Ec-5
Fire safety

Name Class Date

1 Below are two hazard symbols that are particularly important in fires. Identify what each symbol
means, and why any substance with this symbol is dangerous in a fire.
A
This means explosive

This is dangerous because This substance can cause serious damage when

it exploded. These substance can also explode by themseleves.

B This means flammable

This is dangerous because The substance can give off enough vapour to form

burnable mixtures with air. As a result, they can be a serious fire hazard.
2 The table below describes four different fires. For each fire, complete the last two columns in
the table. If you put ‘fire extinguisher’ in the second column, you must also say which type you
plan to use: water, powder, foam or carbon dioxide gas.
Type of fire How to put out the What is removed: heat/
fire fuel/oxygen? (it may be more
than one of these)
chip pan fire Use a foam extingui oxygen
-sher

plane fuel fire heat

electrical fire use a carbon dioxide Oxygen

extinguisher

forest fire Create smaller fires fuel

in the opposite directio
-n to burn the fuel
and stop the fire from
spreading

I can…
● use the fire triangle to explain how to control a fire
● identify hazard symbols for substances likely to cause fires.

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 8 Ec-6
The Great Fire of London

September 1666
What is being described as ‘the great fire’ broke out near London Bridge, last
week. It is thought to have been started accidentally in the oven of a bakery in
Pudding Lane, a narrow street of wooden houses.
The recent strong easterly winds fanned the fire and the flames spread across
the Ludgate region of London for four days, destroying everything in their path.
The lack of water, due to the distance from the river, and the shortage of water
pumps Carbon dioxideattempts
hampered and water to control the blaze. It was feared that the fire would
destroy the whole of the City if it was not stopped, so the decision was taken to
blow up whole streets of houses to make gaps where there were no houses that
Carbon Monoxide and soot
could burn. Despite the protests of the householders, the prompt actions of the
Army in evacuating and blowing up the necessary homes, helped to bring the
fire under control. Change of wind direction, blowing the fire back on to burnt
areas, also helped.
The embers of the fire are still glowing but the fire is now under control and
miraculously there have been few reports of loss of life. The damage to London
has been massive and it is estimated that more than 13 000 homes and a total of
89 churches, including St Paul’s Cathedral, have been destroyed. A local
architect, Mr Christopher Wren, has come forward with outline plans for the
rebuilding of the city, with wider roads, better water supplies and proper
drainage arrangements. It is expected that it will be many years before the
scars of this fire have been removed, but work will start as soon as the debris
can be cleared.

1 How did the Great Fire start?

2 What does this historical report tell you about each of the following:
a the source of heat that started the fire
b the fuel that burnt in the fire
c the supply of oxygen for the fire?
3 Most people lived in wooden houses in London in 1666. How did this help the fire to spread?
4 Why was it difficult to put the fire out once it had started?
5 Do you think the same thing would happen today? Why?
6 What lessons were learnt from the Great Fire of London?
7 When forests are planted today, wide paths are left between blocks of trees. These are called
‘fire-breaks’. How do you think they are meant to stop a fire spreading?
8 What was done to prevent the Great Fire spreading even further? Why do you think the people
of London didn’t do this straight away?
9 What evidence from the report shows that combustion is an exothermic reaction?
Explain your answer.

I can…
● use the fire triangle to explain how to control a fire.

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 8 Ec-7
Energy in fuels

Some alcohols can be used as fuels, like

hydrocarbons. For example, bioethanol is used
instead of petrol in some vehicles.
Students carried out an experiment to compare
the amount of energy released by a range of
alcohols. The diagram shows the equipment
used in the experiment.
In the experiment, the mass of fuel was
measured before combustion. Combustion
continued until 100 cm3 of water increased in
temperature by 30 °C, when the flame was put
out. The mass of fuel left at the end of the
experiment was also measured. The table
shows the results.

Alcohol Initial mass of fuel (g) Final mass of fuel (g)

methanol 256.36 255.88
ethanol 168.05 167.64
propanol 251.34 250.95
butanol 216.35 216.08
pentanol 120.46 120.20
hexanol 275.62 275.37

1 Combustion reactions are exothermic.

a Explain what exothermic means.
b Explain the importance of this for controlling fires.
2 Look at the equipment for the experiment.
a Describe what happens during the experiment.
b Describe one weakness of the experimental set-up for this experiment.
c Explain the importance of your answer to part b for the reliability of the results.
3 Suggest variables that would need controlling during the experiment, and how they could be
controlled.
4 Using the data in the table, calculate the mass of each fuel used.
5 Use your answers to Question 4 to identify the fuel that releases the most energy per gram of
fuel. Explain your answer.
6 The table below shows the price per kilogram of each of the alcohols.
Alcohol methanol ethanol propanol butanol pentanol hexanol
Price per
0.43 0.71 0.86 0.83 6.30 2.46
kg (£)
a Use this information and your answer to Question 5 to suggest which alcohol would make
the cheapest and most useful fuel.
b Suggest what else you might need to know so that you could decide which was the best
fuel to use in a vehicle.

I can…
● evaluate data on burning fuels.

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 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.

Carbon dioxide and water

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

Carbon Monoxide and soot

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

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

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

1 2 poisonous, will kill if too much is

carbon dioxide
breathed in

4 acidic, dissolve in water droplets in

2 carbon monoxide
clouds and cause acid rain

probably causes global warming

3 soot particles 1
and climate change

coat the lining of the lungs when

4 sulfur dioxide and nitrogen oxides 3 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
neutralisation

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

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

to form carbon dioxide .

d In a catalytic converter, nitrogen oxides are broken down to oxygen and nitrogen

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:

I D

H A C J

G
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.

Fossil Fuels

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 + oxygen  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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 8 Ee-1
Global warming

Name Class Date

1 The diagram explains how the greenhouse effect works. Cut out the labels at the bottom of the
sheet and stick them onto the correct places on the diagram.
Some reflected energy is transferred to
space.

As the Earth’s surface gets warmer, it emits

more energy.
Energy is transferred from the Sun to the
Earth’s surface.

Some energy is absorbed by greenhouse

gases and transferred back to the Earth’s
surface.
Most energy is absorbed by the Earth’s
surface, making it warmer.

2 Draw lines to link the sentence starters with their correct endings.

1 Natural causes of changes in the 3 carbon dioxide and other gases.

Earth’s temperature include …

2 5 transport and electricity generation

Global warming is caused by …
from power stations.

the amount of energy transferred from

3 Greenhouse gases include … 2 the Sun to the Earth, and the tilt of the
Earth’s axis.
Global emissions of carbon dioxide an increase in the greenhouse effect
4 have increased over the past 1 because there are more greenhouse
200 years because … gases in the atmosphere.

The largest sources of carbon dioxide 4 there has been an increase in the
5
emissions are … burning of fossil fuel.

I can…
● describe the greenhouse effect and how it is caused
● describe how human activity may be causing global warming.

Some reflected energy is transferred to As the Earth’s surface gets warmer, it emits
space. more energy.

Energy is transferred from the Sun to the Some energy is absorbed by greenhouse gases
Earth’s surface. and transferred back to the Earth’s surface.

Most energy is absorbed by the Earth’s

surface, making it warmer.

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 8 Ee-2
Climate change modelling

Predicting the effect of increasing carbon dioxide and other greenhouse gases in the atmosphere
is very difficult. We understand how greenhouse gases in the atmosphere affect how much of the
energy emitted from the warm Earth’s surface escapes into space and how much is returned to the
surface. However, there are many factors that can affect how much of the Sun’s energy reaches
the ground, how much is absorbed by the Earth and how much escapes into space.

One factor is the amount and type of cloud. Clouds block some of the Sun’s energy from reaching
the Earth’s surface and reflect it away from Earth and back into space. However, energy that is
emitted from the Earth’s surface may be reflected by clouds back to the surface, preventing it from
escaping to space. This will cause the Earth’s surface to get warmer.
Another factor is the colour of the Earth’s surface. Lighter colours reflect more energy, while darker
colours absorb more energy. This is particularly important in relation to ice. Large areas of ice,
such as ice caps, reflect more light than the rock around them. However, the energy the ice
absorbs will cause melting. As the ice melts, more dark rock is exposed and more energy is
absorbed rather than reflected, so more ice melts, and so on. This is an example of positive
feedback, where a change makes more change more likely. Predicting this feedback effect
depends on understanding how ice melts in different situations.
To help predict the future effects of global warming, scientists use computer models that include all
the factors that they know have an effect on the absorption and emission of energy from the
Earth’s surface. These models are huge and complicated. As a result, small changes in a factor
can produce large differences in predicted change. So the modelling program must be run millions
of times, with slight differences in values for factors each time, to see what happens. If many of the
test runs produce a similar result, scientists can be more confident about their predictions using the
model.
In 2013, a project organised by Oxford University via the BBC used thousands of volunteers to run
their climate prediction program. The results of the project predicted a rise in between 2 and 4 °C
in temperature in the UK by 2080. It also predicted warmer, wetter winters and hotter, drier
summers.
Read through the information text above, and then use it to answer these questions.
1 Write a title for this text to sum up what it is all about.
2 For each paragraph, write a sentence that describes the key point in that paragraph. Use no
more than 8 words in each sentence.
3 Use your answers to Question 2 to draw a concept map that links all the key points in the text.

I can…
● use information and explanation text to answer questions clearly.

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 8 Ee-3
Causes of temperature change

Below are some questions about natural causes of change in temperature of the Earth’s surface.
You may also have some questions from earlier in the topic.

● Why is the date of around 1750 often included in discussions of the cause of temperature
change?
● Why does the amount of energy transferred from the Sun to the Earth vary?
● What was the Maunder Minimum, what caused it, and why might it happen again?
● What do scientists suggest caused the last glacial period (often called the ice age), which
began around 100 000 years ago and ended about 12 000 years ago, and could it happen
again?

1 In your group, decide which question you will each research.

2 When you carry out your research, make notes of what you find out.

3 Use your notes to write a paragraph that answers the question you researched.
Remember, a well-constructed paragraph starts with a topic sentence followed by supporting
sentences, and ends with a summary sentence.

4 Exchange paragraphs with someone else in your group. Check that their paragraph:
a answers the question they researched.
b is structured properly.

5 Mark two good points about the paragraph, and one point that could be improved. Explain why
it needs to be improved.

6 Exchange paragraphs again, so that you have the one you wrote. Rewrite what needs
improving.

7 Your teacher will then explain how your group will combine your research for presentation.

I can...
● write a well-constructed paragraph
● give reasons why Earth’s temperature varies over time.

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 8 Ee-4
Carbon dioxide emissions

Name Class Date

The drawing below shows some sources of carbon dioxide from human activities.
1 Label the drawing to show which human activities produce carbon dioxide, and why they
produce carbon dioxide.
2 For each label, add notes to explain how the amount of carbon dioxide produced by that activity
could be reduced. Try to think of more than one way of reducing emissions from each source.

I can…
● explain how carbon dioxide emissions from human activity can be controlled.

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 8 Ee-5
Which car?

Name Class Date

The table compares two cars of similar size and power that run on different fuels.

Petrol car Diesel car

New car price £19 100 £21 090

Fuel use 10 miles per litre 13 miles per litre

Estimated running cost for 3 years £15 964 £15 300

1 a Which is the more expensive car to buy? Diesel car

b Which car costs the least to run over 3 years? Diesel car

c Which car uses the least fuel when driving? Diesal car

d Explain how you chose your answer to part c. it takes a diesel car 13 miles to use up 1 litre of fuel

but it takes a petrol car only 10 miles to use up 1 litre of fuel meaning that a diesel car uses the least amount
of fuel
2 Carbon dioxide is released when petrol and diesel burn. Carbon dioxide is linked to global
warming.
a What do we mean by ‘global warming’?

b Describe one effect that global warming might have.

Global warming increases the temperature of the earth daily

c Use your answer to Question 1c to identify which car might be chosen by someone who is
concerned about global warming. Explain your answer.

3 Some people choose to drive cars that run on electric batteries. The batteries are charged by
plugging them in to the mains electricity supply. When the car drives no fuel is burnt.
a How does driving an electric car help the environment?

b Electricity is generated in power stations. Most UK power stations burn fossil fuels.
Explain why driving an electric car is not as environmentally friendly as it might first seem.

I can…
● state the meaning of global warming and describe some of its effects
● explain how some human activities affect carbon dioxide emissions.

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 8 Ee-6
Climate change

1 a What do most scientists think is causing the rise in global temperatures?

b What effects could this temperature rise have?
2 a What is meant by the ‘greenhouse effect’?
b Would we be better off on Earth without the greenhouse effect? Explain your answer.
3 List two main causes of the rising concentration of carbon dioxide in the atmosphere?
4 Look at the graphs below. Graph A shows the changes in carbon dioxide concentration over
the last 1000 years in parts per million (ppm). Graph B shows the mean temperature of each
year compared to the mean temperature for the years 1961–1990 (this is set at 0 on the
graph). The dashed line shows the predicted increase in temperature from 2000.

a What was the carbon dioxide concentration (approximately) between 1000 and 1800?
b In 1900, how much lower was the mean temperature than it was in 1961–1990?
c In which year did temperature levels start to rise above the mean value for 1961–1990?
d Describe the current trend in carbon dioxide concentration.
e What has been the general trend in mean world temperature over the last 100 years?
f What does the graph predict will happen to mean temperature over the next 100 years?
g Using the graphs, describe any link between the mean world temperature and the carbon
dioxide level.
h Do you think these graphs provide good evidence that rising temperatures are caused by
rising concentration of carbon dioxide? Explain your answer.
5 Scientists use computer models to predict how rising temperatures could affect the future
climate of the Earth.
a What information do you think they need to put into such computer models?
b Suggest why different computer models give different predictions about future climates.

I can…
● recall the causes and effects of global warming
● interpret information from graphs.

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 8 Ee-7
Global warming evidence

1 a Sometimes two variables are linked. Look at graph A and describe the link between
changes in temperature and changes in the amount of carbon dioxide in the air.

A The mean (average) Earth surface temperature and

carbon dioxide concentration in the air over the past 250
000 years.

b One interpretation of graph A is that carbon dioxide causes warming. Explain how this is
thought to happen.
c A link between two variables does not necessarily mean that a change in one causes a
change in the other. Suggest one other possible interpretation of graph A.
Evidence from temperature measurements clearly shows that global warming is happening now.
Many people use the patterns in graph A to say that emissions of carbon dioxide from human
activities are causing the global warming. Others disagree and say that human activity is not the
cause of global warming. Some statements are better supported by evidence than others.

2 a Match up the boxes below to form pairs covering the

same point. One box argues in favour of human
activity causing global warming and the other argues
against.
b For each pair, decide which box contains the ‘stronger’
statement. Give a reason for each decision.
c Look at poster advert B. It was produced by a group
that does not think human activity has caused global
warming. Design your own poster that has the
opposite message.

More than 31 000 scientists don’t think A number of different studies of different
that human activity is causing global aspects of climate, covering different times in
warming. Earth’s past, all lead to a conclusion that a
doubling of carbon dioxide in the air will raise
the temperature by about 3 °C.
The Sun could be causing global warming The link between solar activity and Earth
because when there are more sunspots, temperature is sometimes, but not always,
the Sun is more active and the Earth gets true. At the moment, though solar activity is
warmer. quite low, warming is still increasing.
Fossils and rocks show that there have Computer models do show that small changes
been warmer times in the past even when can make big differences. But many different
carbon dioxide concentration was lower models, run thousands of times, all suggest
than now. So current changes could be that the amount of carbon dioxide released by
natural. human activity is causing a warming effect.
Computer models are not complicated Over 97% of published papers on global
enough to get it right, and tiny changes warming agree that human activity is the
can make great differences. Therefore, cause.
we can’t be sure that the models are right.

I can…
● evaluate evidence for and against the idea that human activity is causing global warming.

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 8 Ee-8
Whose responsibility?

Most people agree that carbon emissions must be cut to help control global warming. However,
deciding how to share the responsibility can be challenging, as there is always a cost involved.

International responsibility
The United Nations (UN) holds climate talks between all countries and tries to organise global
deals for cutting carbon emissions. The aims of climate talks in 2015 include setting targets for
reducing global carbon emissions that are to be met by 2020.
In the 2013 UN climate talks, China and India refused to accept ‘commitments’ to reducing carbon
dioxide emissions. China and India believe that developed countries (such as the US, Japan and
European countries) should make commitments to reduce emissions, while emerging economies
(such as China, India, and African and South American countries) should only be expected to look
for ways to do so.
1 Increasing carbon emissions is related to increasing industrialisation (factories, electricity
generation and use of road vehicles). Explain why.
2 Increasing industrialisation is related to increasing wealth for a country and better living
conditions for many of the people who live there.
a Suggest why the governments of China and India believe that developed countries should
make commitments but emerging economies shouldn’t.
b Suggest why many governments of developed countries think that countries with emerging
economies should make commitments to carbon emission reduction.
3 The cheapest electricity is usually generated from a country’s own natural resources (e.g. coal,
oil, hydroelectric (from water) or nuclear). Explain why flexibility in the way countries set carbon
emission targets is essential.

National responsibility
Electricity generation is the largest source of carbon dioxide emissions in the UK. Different ways of
producing electricity release different amounts of carbon dioxide.
● Coal, gas and oil are the cheapest sources of electricity, but all are fossil fuels and so release a
lot of carbon dioxide when burnt.
● Nuclear power stations produce almost no carbon dioxide. However, they are expensive to
build and there are concerns over what to do with the dangerous nuclear waste that is
produced.
● Renewable energy sources also produce no carbon dioxide. However, methods using wind and
sunlight produce relatively small amounts of electricity compared with fossil fuels and nuclear
power. For example, one nuclear power station produces more electricity than over 1000 wind
turbines. Hydroelectricity, which needs large lakes or reservoirs, can be produced on a large
scale but only a few places in the UK are suitable.
4 The UK Government sets targets for reducing carbon dioxide emissions to achieve UN goals.
a What do you think the UK Government should do to achieve the targets they set?
b What do you think industry should do to help achieve national targets?
c How should individual people be involved in achieving national targets?
d Remember that people make choices depending on how change will affect them and what
they think is important. How could this cause problems for achieving national targets, and
how could those problems be tackled?

I can…
● decide how responsibility for cutting carbon dioxide emissions should be shared.

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 8 Ee-8
Whose responsibility?

Measuring your results

M Place one of the cards on a microscope stage and adjust the lenses so you can see the
particles in the squares.
N Count the number of particles in at least five different squares and write the numbers down.
O Work out a mean number of particles for each square.
P Repeat steps M–O for your other cards.

Recording your results

1 Record your results in a neat table.

Considering your results/Conclusions

2 a Which site contained the most air pollution?
b How do you know this?
c Suggest a reason for this result.

Evaluation
3 a Why did the sticky film have to be kept covered when it was not being used for collecting?
b Why must you avoid touching it with your fingers?
c Why did it need to be protected from rain?
4 Why did you have to leave all the cards in place for the same length of time?
5 How did you choose which squares on each card to use for the counting? Explain your answer.
6 Many variables 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 Which of these variables did you control?
c Why didn’t you control the other variables?

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

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