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242 © Pearson Education Limited 2002Exploring Science for QCA Copymaster File 7

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7Fa

1 Two liquids were mixed together in a testtube. Which one of these would not showthat a chemical reaction had taken place?

A The tube got warm.

B Bubbles of gas were given off.

C A brightly coloured solid formed in the tube.

D One of the liquids floated on top of the other.

2 Which of these changes is a chemicalreaction?

A melting some margarine in a pan

B boiling a kettle of water

C frying an egg

D cooling a drink by putting an ice cubein it

3 Which statement is true?

A All reactions need energy to start them off.

B Some reactions need energy to startthem off.

C All reactions happen when twochemicals are mixed.

D All reactions happen very quickly.

4 A chemical reaction:

A always produces a gas.

B is always reversible.

C makes new substances.

D does not make new substances.

7Fb

1 Which kind of chemical will react with anacid to form hydrogen?

A metal

B water

C carbon

D petrol

On your answer sheet, write in or circle the correct letter for each question.

7

F

7F Quick Quiz

2 The substances that you get at the end ofa chemical reaction are called:

A reactants.

B chemicals.

C products.

D gases.

3 Hydrogen gas:

A burns with a squeaky pop.

B makes a glowing splint relight and burnbrightly.

C puts a glowing splint out.

D turns universal indicator solution red.

4 Which of these substances is naturallyacidic?

A wood

B sand

C limestone

D rainwater

7Fc

1 Which two chemicals would you mixtogether to make carbon dioxide?

A an acid and a metal

B an acid and a carbonate

C an alkali and a metal

D an alkali and a carbonate

2 Carbon dioxide is used:

A to make the bubbles in fizzy drinks.

B to fill party balloons.

C to help people breathe more easily.

D in gas cookers, to provide heat.

3 Which of these will show that a gas iscarbon dioxide?

A milk turns to water

B rosewater turns pink

C limewater turns milky

D burns with a squeaky pop

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7F Quick Quiz (continued)

7

F

4 Which substance does not containcarbonates?

A indigestion tables

B limestone

C baking powder

D sugar

7Fd

1 When a metal burns it:

A combines with oxygen from the air.

B combines with nitrogen from the air.

C gives off carbon dioxide.

D gives off oxygen.

2 Which is the correct equation to showwhat happens when magnesium burns?

A magnesium + nitrogen Æ magnesiumnitride

B magnesium + oxygen Æ magnesiumoxide

C magnesium + oxygen Æ carbon dioxide+ water

D magnesium oxide Æ magnesium +oxygen

3 A fire needs three things to keep burning.They are:

A coal, air, smoke

B natural gas, wood, heat

C heat, fuel, nitrogen

D heat, fuel, oxygen

4 A fire can be put out by:

A removing its fuel.

B removing its oxygen.

C cooling it down.

D any of the above.

7Fe

1 Which list contains only fuels?

A wood, iron, plastic

B wood, petrol, oxygen

C petrol, oil, natural gas

D air, wood, oil

2 When a fuel burns there is:

A a reversible physical change.

B a reversible chemical change.

C an irreversible physical change.

D an irreversible chemical change.

3 Which statement finishes off this wordequation for burning?

fuel + oxygen Æ

A carbon dioxide + water (+ energy)

B carbon dioxide + carbon monoxide

C fuel oxide + oxygen (+ energy)

D methane + carbon dioxide (+ energy)

4 Which of these candles will burn thelongest?

A B

C D

volume of air = 150 cm3





7F Target Sheet

Topic Targets Before the unit I have learned this I have revised this7Fa 1 Know what to look for to see if a

chemical reaction has occurred.

2 Give some examples of chemical reactions.

3 Know how chemical reactions can be started.

4 Explain the difference between a physical and chemical change.

7Fb 1 Know which kinds of chemical react with acids to form hydrogen.

2 Know the meaning of the words reactant and product.

3 Know how to test a gas to see if it is hydrogen.

4 Know where acids can be found in the environment.

7Fc 1 Know which kinds of chemical react together to form carbon dioxide.

2 Give some examples of where carbon dioxide can be found.

3 Know how to test a gas to see if it is carbon dioxide.

4 Know some examples of carbonates.

7Fd 1 Know what happens when metals burn.

2 Be able to write word equations toshow what happens when metals burn.

3 Know the three things a fire needs to keep burning.

4 Know how a fire can be put out.

7Fe 1 Know some examples of fuels.

2 Know what happens when a fuel burns.

3 Be able to write a word equation for burning.

4 Know that burning uses up oxygen.

7

F

Name Class

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7F Word Sheets

7

F

Word Pronunciation Meaning

chemical reaction A change where new substances are formed.

irreversible change Permanent change.

permanent change A change in which what you ended up with cannot be turned back into what youstarted with.

physical change fizz-ick-al A change where no new substances are formed.

reversible change A change in which what you end up with can easily be turned back into what you started with.

7Fa – Getting a reaction


acid rain Rain containing sulphuric and nitric acid.

corrosion When stone or metal reacts with chemicals in air or water and is worn away orchanged into a different substance.

corrosive cor-row-sive Substances that attack metals, stonework and skin are called corrosive.

hydrogen A gas which is given off when metals react with acids. It burns with a squeaky pop.

product New chemical formed in a chemical reaction.

reactants Chemicals that join together to form a new substance.

rust Substance formed when iron or steel reacts with oxygen and water.

7Fb – Fizzy pop


carbon dioxide A gas which will put out a lighted splint and turn limewater milky.

limewater A chemical that goes cloudy when carbon dioxide is bubbled through it.

7Fc – Fizz and chips

Word sheets that include new words from the ‘Focus on:’ pages are available on theExploring Science website.


Page 2 of 2

7

F

7F Word Sheets (continued)


chemical energy The kind of energy stored in chemicals.

fuel A chemical that can release energy when it reacts.

oxide A compound that includes oxygen.

word equation A way of writing out what happens in a chemical reaction.

7Fd – On fire!


chemical reaction When new substances are formed.

combination reaction When chemicals join to form new substances.

combustion The scientific word for burning.

hydrocarbon A chemical compound containing only hydrogen and carbon.

irreversible action A reaction in which what you end up with cannot be turned back into what youstarted with.

oxide A compound that includes oxygen.

word equation A way of writing out what happens in a chemical reaction.

7Fe – Burning issues

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7F End of Unit Test

Name Class

1 Which two of these are chemical reactions? Tick two boxes.7

F

You dissolve a spoonful of sugar in water.

Bread goes brown in the toaster.

You take an ice lolly out of the freezer and it starts to melt.

Frost forms on the grass on a cold night.

You strike a match to light a Bunsen burner.[2 marks]

2 a Is burning a chemical reaction or a physical change? Tick one box.

chemical reaction physical change

[1 mark]

b Explain why you chose your answer to part a.

[1 mark]

3 Sara added acid to some calcium carbonate in a tube. The gas given off was bubbledthrough the limewater and turned it milky after one minute.

limewater

calciumcarbonate

acid

a Write down one thing that tells you a reaction has taken place.

b Name the gas that turned the limewater milky.

c Which word could be used to describe the calcium carbonate and the acid?

Circle the correct answer.

products gases reactants solids

[3 marks]


Page 2 of 3

7F End of Unit Test (continued)

4 a Which substance reacts with an acid to form hydrogen gas? Circle the correct answer.

carbonate oxygen carbon dioxide magnesium gold

b How would you test the gas given off to show that it was hydrogen?

[3 marks]

5 a Complete the missing words on this fire triangle:

7

F

[2 marks]

b Why do we put these three words together in the ‘fire triangle’?

[1 mark]

c Give two examples of fuels.

[1 mark]

6 a You should never use water to put out an electrical fire. Why not?

[1 mark]

b You can put out a chip pan fire by putting a damp cloth over the pan. Explain why this works.

[1 mark]

c Fires in forests can sometimes be stopped by cutting down trees to make a gap(called a ‘fire break’). Which part of the fire triangle does this remove?

[1 mark]

FUEL

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7F End of Unit Test (continued)

7

7

F

Magnesium burns with a very bright light. When the flame goes out, a whitepowder is left.

a What is the name of the white powder?

[1 mark]

b Write a word equation for this reaction.

[1 mark]

c The mass of the strip of magnesium was 0.15 g. If you collected all the whitepowder together, what would its mass be? Tick one box.

about 0.1 g about 0.15 g exactly 0.15 g about 0.25 g

[1 mark]

d Explain why you chose your answer to part c.

[2 marks]

8 Complete this word equation:

fuel + Æ + (+ energy)

[3 marks]


Page 1 of 2

7F Summary Sheets

Chemical reactionsIn a chemical reaction a new substance is always formed. Most chemical changesare not easily reversed; they are irreversible. In a physical change no newsubstance is formed. Melting and evaporation are examples of physical changes.Physical changes are usually reversible.

You can tell that a reaction has occurred if there is a colour change or when a gas isgiven off. Most chemical reactions also involve an energy change. This is usually inthe form of heat, but can also involve light being given off (for example, whensomething burns).

Reactions of acidsSome metals react with acids, and hydrogen gas is produced. When acids react withchemicals called carbonates, carbon dioxide gas is given off. Carbonates are found inrocks such as limestone or marble, and in some cooking ingredients and indigestiontablets.

You can test the gas made in a reaction to find out what it is:

• Hydrogen burns with a squeaky pop if a lighted splint is held near the test tube.• Carbon dioxide will put out a lighted splint, and it makes limewater turn milky.• Oxygen makes flames burn more brightly, and will relight a glowing splint.

BurningWhen a metal burns, the metal combines with oxygen from the air to form a chemicalcalled an oxide. We can show this using a word equation. The chemicals that youstart with are called the reactants. The chemicals at the end are called the products.

magnesium + oxygen Æ magnesium oxidereactants products

Fossil fuels contain a lot of carbon and hydrogen. When they burn they use upoxygen from the air and produce water and carbon dioxide. We can show the reactionusing a word equation. Energy is in brackets in this equation because it is not achemical substance.

fuel + oxygen Æ carbon dioxide + water (+ energy)

7

F

Simple chemical reactions

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7F Summary Sheets (continued)

FireA fire needs three things to keep burning: fuel, oxygen and heat. We show these threethings on the Fire Triangle. 7

F

FUELO

XY

GE

N HE

AT

If any one of these three things runs out, the fire will go out.

Fire extinguishers are used for putting out fires. There are different types of fireextinguisher, and it is important always to use the correct sort for a particular fire.Sand or fire blankets can also be used to put out fires.

Water is often used to put out fires, because it takes away the heat. However, watershould never be used on oil or petrol fires, because it makes the burning fuel spread out.

Foam, powder or carbon dioxide (CO2) extinguishers work by stopping oxygen gettingto the flames.

7F

139

7F Mark schemes

Exploring Science for QCA Teacher’s Guide 7 © Pearson Education 2002

Question Answers Marks

Topic 1 2 3 4

7Fa D C B C 4

7Fb A C A D 4

7Fc B A C D 4

7Fd A B D D 4

7Fe C D A B 4

Question Level Answers Mark scheme

1 3 Ticks in the ‘bread’ and ‘striking a match’ boxes 2 marks – 1 per tick. Allow 1 mark if both correct boxes have been ticked and one additional incorrect box

2 4 a Chemical reaction 1 mark4 b It is irreversible; or new substances are made 1 mark – accept equivalent answers

3 4 a solid changes colour (from green to black) 1 markor gas given off

6 b carbon dioxide 1 mark5 c reactants 1 mark

4 6 a magnesium 1 mark6 b hold a lighted splint in the tube; 1 mark6 the gas will burn with a squeaky ‘pop’ 1 mark – accept equivalent answers

5 4 a Oxygen, heat 2 marks – 1 mark for each answer4 b They show us the three things that a fire needs 1 mark – accept equivalent answers

to keep going4 c Any two examples of fuels, e.g. coal, oil, petrol, 1 mark

natural gas, wood

6 4 a You might get an electric shock 1 mark4 b It stops oxygen getting to the fire 1 mark4 c Fuel 1 mark

7 6 a Magnesium oxide 1 mark6 b magnesium + oxygen Æ magnesium oxide 1 mark7 c About 0.25 g 1 mark7 d The magnesium has reacted with oxygen from the 2 marks – 1 mark for each point. Accept equivalent answers

air; so the mass of the magnesium oxide is greaterthan the mass of the magnesium

8 6 Oxygen, carbon dioxide, water (last two in 3 marks – 1 mark for each correct answer6 either order)

Quick Quiz

End of Unit Test marks

Level Marks Cumulative Suggested available total threshold for

achieving level

3 2 2 2

4 10 12 8

5 1 13 10

6 9 22 17

7 3 25 22

Matching End of Unit Test marks to NC levels


Page 1 of 2

7Fa/1 Is there a

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of 2


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7Fa/2 Is there a

reaction? 2

observing, consideringS

Carry out the experiments described below. In each case, you should:

• look carefully at what happens and write down your observations• decide if a reaction has taken place• see if any changes are reversed when you stop heating or leave the tube to stand• decide if a chemical reaction has taken place• record your results in a table.

Method – experiment 1Half fill a test tube with lemon juice. Measure the temperature of the lemonjuice. Add a spatula of bicarbonate of soda. Leave the tube to stand, thenmeasure the temperature again.

Method – experiment 2Half fill a test tube with water. Add a spatula of baking powder. Observe whathappens.

Method – experiment 3Half fill a small beaker with water. Add two spatulas of plaster of Paris. Stir themixture.

Method – experiment 4Place two spatulas of zinc oxide in a test tube. Heat the tube gently. If nothinghappens, use a hotter flame. Leave the hot tube in a rack to cool down.

Method – experiment 5Half fill a test tube with copper sulphate solution. Put a little iron wool into thecopper sulphate. Leave the tube to stand.

Method – experiment 6Put about 3 cm depth of water into a test tube. Measure the temperature of thewater. Put a spatula of anyhdrous copper sulphate into another tube. Make surethat this tube is dry. Pour the water into the second tube. Watch what happensand measure the temperature of the solution.

P Apparatus� Bunsen burner � Eye protection� Heatproof mat � Test tube holder� Test tube rack � Test tubes� Thermometer � Chemicals

�Make sure you are wearing eye

protection for all theseexperiments.

Be especially careful with the hydrochloric acid and

sodium hydroxide.


7Fa/3 Reaction or no

reaction? 1

Name Class

7

F

a

knowledgeS

1 Choose the correct words to complete these sentences.

No new substances are formed when a (chemical/

physical) change happens. Physical changes are

(irreversible/reversible/permanent) changes.

New substances are formed when a (chemical/physical)

reaction happens. You can tell a (chemical/physical)

reaction has happened if something changes

(hardness/colour) or if a (gas/solid) is given off.

Sometimes there is a change in (energy/softness).

2 Complete the following sentences.

a If you put some water into a freezer, it turns to ice. You can tell that this

(is/is not) a chemical reaction because

b Bananas turn black if you leave them in a warm cupboard for a week.

You can tell that this (is/is not) a chemical reaction

because

c Some white powder from your kitchen fizzes when you put it into

vinegar. You can tell that this (is/is not) a chemical

reaction because

d When you boil water in a kettle, some of it turns to steam. You can tell

that this (is/is not) a chemical reaction because

e When you fry an egg it turns white and goes solid. You can tell that this

(is/is not) a chemical reaction because

?


7Fa/4 Reaction or no

reaction? 2

7

F

a

knowledge, literacyS

1 In the passage below the words in italics are anagrams – the letters havebeen jumbled up. Copy out the passage with all the words spelt correctly.

When fireworks go off, you see coloured thligs and hear loud bangs. Thesechanges show that chemical snoriacte are happening. New busnatsces arealways formed in a mechalic reaction, and it is usually very difficult toservere the nortiace. Chemical changes are usually mantenrep changes. Whena chemical reaction happens, there may be a roclou change or a change inpermteartue, and sometimes a sag is given off.

Not all changes are mechalic changes. A shlicpay change is one that can bedeserver fairly easily. When ice stelm no wen substances are formed. This is ashlicpay gencah, because the tarew can be made back into cie quite easily.

2 Look at each of the situations below. Decide whether or not each one is achemical reaction. Explain why you have come to your decision.

a If you put some water into a freezer, it turns to ice.

b Bananas turn black if you leave them in a warm cupboard for a week.

c Some white powder from your kitchen fizzes when you put it into vinegar.

d When you boil water in a kettle, some of it turns to steam.

e When you fry an egg it turns white and goes solid.

f Your ice cream melts and runs over your hand.

?


7

F

a

7Fa/5 Useful and harmful

reactions The boxes below give some examples of chemical reactions. Think about which onesare useful and which are harmful, and why you think each reaction is useful orharmful. In a few cases, the same reaction can be both helpful and harmful. In thesecases, there are two separate statements.

When you have done this, you will need to think about how to report your work. You might:

• draw up a table with the headings ‘helpful’ and ‘harmful’ and write each reactionin the correct column with your reasons for putting it there.

• have two pages in your book, one for useful and one for harmful reactions, andillustrate each page. Remember to say why you think each reaction is useful orharmful.

• use a computer with ‘clip-art’ to produce a mini-poster of useful and harmfulreactions, and the reasons you think they are useful or harmful.

knowledgeS

1 You burn natural gas in a boiler.

2 Parts of a car start to go rusty.

3 You cook some chips in the oven.

4 Petrol is used in a car engine.

5 Petrol used in a car engine gives off exhaust fumes.

6 You use a ‘catalytic converter’ to reduce the pollution from car exhausts.

7 Acid rain corrodes a limestone building.

8 Chemicals in an anti-spot cream react with a silver necklace, turning it black.

9 ‘Perming lotion’ is used to make hair curlier or straighter.

10 Ozone in the upper atmosphere absorbs ultra-violet rays and changes intonormal oxygen.


Page 1 of 2

How can you collect the gas given off in an experiment?

7Fb/1 Collecting gas

7

F

b

Method

1 Fill the test tube and the beaker with water. Put your thumb over the end of the test tube, and put it into the beaker upside down.

P Apparatus� Eye protection � Boiling tube� Test tube � Large beaker� Bung and delivery tube � Test tube rack� Piece of magnesium (1 cm long) � Measuring cylinder� Dilute hydrochloric acid � Bunsen burner � Splints � Test tube holder

�Wear eye

protection.

2 Put the end of the delivery tube into the upside down test tube, withoutletting any of the water out.

3 Measure 10 cm3 of hydrochloric acid and put it into a boiling tube. Stand the boiling tube in the test tube rack.

of 2



7Fb/1 Collecting gas (continued)

7

F

b

Considering your results/conclusions

1 What are the names of the two reactants in this experiment?

2 What did you see happening when you put the magnesium into the acid?

3 How could you tell that one of the products of this reaction is a gas?

4 What happened when you tested the gas in the boiling tube?

5 What does this tell you about the gas?

4 Drop the piece of magnesium into the acid, and put the bung into the top ofthe tube.

P

5 Watch what happens to the magnesium and the acid.

6 When the reaction has finished, light your Bunsen burner.

7 Carefully test the gas in the upside down tube using a lighted splint.


Page 1 of 2

Name Class

7Fb/2 Metals and acids 1

7

F

b

Which metals and acids react with each other?

Method

1 Measure 10 cm3 of an acid and put it into a test tube.

2 Drop a small piece of metal into the acid.

3 Look carefully at the test tube. What can you see happening?

4 Write what you see in the table. You may need to wait a few minutes to see ifanything happens. If you cannot see anything happening, write ‘no reaction’.

5 Wash out your test tube. Ask your teacher what to do with the piece ofmetal if it has not reacted.

6 Repeat steps 1 to 5 for the other combinations of metals and acids.

P

Recording your results

Apparatus� Eye protection � Test tubes� Test tube rack � Dilute acids� Measuring cylinder � Small pieces of metal

�Wear eye protection.

Acidhydrochloric sulphuric nitric

Metal

aluminium

copper

iron

magnesium

tin

zinc

of 2



7Fb/2 Metals and acids 1 (continued)

7

F

b

Considering your results/conclusion

I could tell that a particular combination of metal and acid had reacted because

The metal that reacted fastest with acid was

These metals did not react at all:


Which metals and acids react with each other?

S planning, observing, presenting, considering, evaluating

7Fb/3 Metals and acids 2

7

F

b

You are going to find out which metals and acids will react together.

Planning

1 Write a method for your investigation. You will need to think about these things.• Which metals will you test?• Which acids will you use?• How much acid and metal will you need to use each time?• How will you know whether or not there has been a reaction?• How will you make sure your experiment is safe? (Hint: think about the acids

and metals you are using as well as the method.)

2 Make a table ready for your results.

3 Show your method to your teacher before you start.


4 Design a table to show your results. You could make a column for each acid and arow for each metal, and record your observations in the boxes in the table.


5 Did any of the acids react faster than the others? How do you know?

6 Did any of the metals react faster than the others?

Evaluation

7 If you had time to do your investigation again, could you improve it? Explain how.

Apparatus� Eye protection � Test tubes� Test tube rack � Dilute acids� Measuring cylinder � Small pieces of metal



Sunita and Danny did anexperiment using metalsand acids. They wanted tosee which metal reactedthe fastest. This diagramshows their results.


7Fb/4 Fizzy metals 1

7

F

b

1 How can you tell that the reactions are producing a gas?

2 a What is the gas that the reactions are producing?

b Describe how they could test for this gas.

3 a Which metal reacted the fastest?

b How did you work out your answer to part a?

4 Danny made a mistake in the experiment. Two of the metals were the same.

a Which two metals were the same as each other?

b How did you work out your answer?

5 Write down two things that Sunita and Danny must keep the same eachtime to make sure their test is fair.

i

ii

6 Complete the following sentences using words from the box. You do notneed to use all the words.

Acids and can together.

We know that a reaction has

happened because a new substance is formed.

gas is a of the reaction.

The and the metal are .

?

acid chemical

hydrogen metals

new oxygen

physical product

react reactants

A B C D E


S knowledge

7Fb/5 Fizzy metals 2

7

F

b

Sunita and Danny did anexperiment using metalsand acids. They wanted tosee which metal reactedthe fastest. This diagramshows their results.

1 How can you tell that the reactions are producing a gas?

2 a What is the gas that the reactions are producing?

b Describe how they could test for this gas. Write down the apparatus theywould need, and what they would see happening.

3 Which metal reacted the fastest? Explain your answer.

4 Danny made a mistake in the experiment. Two of the metals were the same.

a Which two metals were the same as each other?

b How did you work out your answer?

5 Which things should Sunita and Danny keep the same each time to makesure their test is fair? You should be able to write down at least three things.

6 a Which chemicals are the reactants in the reaction?

b Which chemical is one of the products?

7 Use these clues to work out the names of the metals that Danny and Sunitatested, and which metal they did not test at all.• Zinc reacts faster than iron.• Copper does not react with acids at all.• Iron does not react as quickly as aluminium and magnesium.• Aluminium reacts faster than zinc, but not as fast as magnesium.

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A B C D E


Hydrogen is a very useful chemical, and it is very common. Most of the Sun is madeof hydrogen. Hydrogen is also part of most of the chemicals that make up your body.In fact, astronomers think that 90% of the universe is made of hydrogen!

Hydrogen can be used to make fertilisers. It can also be used to convert vegetable oilinto margarine, and to make other chemicals such as hydrochloric acid (needed tomake electronic equipment). Liquid hydrogen can be used as a rocket fuel, and it caneven be used to generate electricity for spacecraft.

literacy, knowledge, researchS

7Fb/6 All about hydrogen

7

F

b

1 Which is the most common substance in the Universe?

2 Write down the names of two chemicals that contain hydrogen.

3 Describe three different ways of making hydrogen from other chemicals.

4 Why is hydrogen useful? Write down as many uses as you can.

5 Some people think we should use hydrogen as a fuel for cars, instead ofpetrol. Do you think this is a good idea? Explain your answer.

6 Find out:• how hydrogen can be made into a liquid• what a fuel cell is, and why it is so useful in spacecraft.

?

You have seen how hydrogen can be made by reacting a metal with an acid. However, this is not how hydrogen is made in industry. Many different chemicalscontain hydrogen, and hydrogen can be obtained by splitting up these chemicals in different ways.

The gas that you burn in a Bunsen burner is called natural gas, and the chemicalname for it is methane. Methane is made up of hydrogen and carbon. Methane can bemade to react with steam, and one of the products of the reaction is hydrogen.

Water is another chemical that includes hydrogen. If electricity is passed throughwater, it splits up to form hydrogen and oxygen gases. Water can also be made toreact with red hot iron, and hydrogen is one of the products of the reaction.


Name Class


7Fc/1 Find the carbonate

7

F

c

How can we find out which materials contain carbonates?Carbon dioxide is formed when an acid is added to a carbonate. Carbon dioxide is agas. You can see that a gas is being made because the acid will ‘fizz’.


Method

1 Collect the materials you are going to test, and write their names in the table.

2 Put one of the materials into a boiling tube.

3 Add five drops of acid to the tube.

4 Watch carefully, and write your observations in the table.

5 Ask your teacher what to do with the material you have left. Wash out thetest tube.

6 Repeat steps 2 to 5 for your other materials.

P Apparatus� Eye protection � Boiling tube� Test tube rack � Hydrochloric acid� Materials to test


Considering your results/conclusionFill in the last column of the results table to show which materials contained carbonate.

How did you know which materials contained carbonate?

Material Observation Carbonate? (� or ✗)


Limestone and marble are rocks that are made mainly of a chemical called calciumcarbonate. You are going to carry out a set of reactions that will change limestone into limewater.


7Fc/2 Making limewater

7

F

c

Considering your results

When you heat limestone strongly, the calcium carbonate decomposes into carbondioxide gas (which escapes into the air) and calcium hydroxide. You can show thischange using a word equation.

calcium carbonate Æ calcium oxide + carbon dioxide

The piece of limestone you heated had calcium oxide on the outside. When you addedwater you changed the calcium oxide to calcium hydroxide. Some of the calciumhydroxide dissolved in the water to make limewater.

When you blow carbon dioxide through limewater, some of the calcium hydroxidechanges to calcium carbonate again. Calcium carbonate is insoluble.

Method

1 Put the piece of limestone on a tripod and gauze, and heat it strongly for 5 minutes.

2 Turn the Bunsen burner off and allow the limestone to cool for 5 minutes. Do not touch it.

3 Half fill the beaker with water, and use the tongs to put the piece oflimestone into it. Stir the limestone in the water.

4 Filter the water. The solution you have made is limewater.

5 Use the straw to blow gently into the limewater. What do you see?

6 Filter the liquid that you have blown into. What do you find on the filter paper?

P Apparatus� Eye protection � Bunsen burner � Tripod� Gauze � Heatproof mat � Tongs� Beaker � Test tube � Straw� Filter paper � Funnel � Conical flask� Stirring rod � Piece of marble or limestone (1–2 cm3)

�Wear eye

protection.

1 Write a word equation showing what happened in step 3 of the method.

2 Why did you filter the mixture in step 4?

3 Write a word equation for the reaction that happened in step 5 of the method.

4 Explain why you can see the calcium carbonate but not the calcium hydroxide.

5 What substance do you find on the filter paper after step 6?

?


Name Class

knowledgeS

7Fc/3 Reactions of acids 1

7

F

c

Acids can be corrosive. Acids react with many substances to form new materials. Oneof these materials is often a gas.

1 How can you tell from the diagram that a reaction is happening in the test tube?

If you looked at the thermometer while the reaction was happening, what would you see?

What safety precautions should you take if you did this experiment?

2 Describe how you would test a gas to see if it is hydrogen.

If the gas is hydrogen, what would you see?

3 Describe how you would test a gas to see if it is carbon dioxide.

If the gas is carbon dioxide, what would you see?

4 Which gas would you get if you carried out these reactions?

hydrochloric acid + magnesium produces gas

nitric acid + calcium carbonate produces gas

hydrochloric acid + magnesium carbonate produces gas

sulphuric acid + magnesium produces gas

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Acids can be corrosive. Acids react with many substances to form new materials. One of these materials is often a gas.

7Fc/4 Reactions of acids 2

7

F

c

1 a How would you know if a gas was being produced in a reaction?

b Copy this test tube, and draw what you would see if the reaction was producing a gas.

2 a Describe how you would test a gas to see if it was hydrogen.

b How would you know whether or not the gas was hydrogen?

c Write a list of the apparatus you would need.

d What safety precautions should you take when doing this test?

3 a Describe how you would test a gas to see if it was carbon dioxide.

b How would you know whether or not the gas was carbon dioxide?

4 Look at the list of substances below.

a Write down two substances that would react with an acid to producehydrogen gas.

b Write down two substances that would react with an acid to producecarbon dioxide gas.

?

knowledgeS

calcium oxide calcium carbonate iron oxide

magnesium magnesium carbonate magnesium oxide

aluminium sodium chloride

5 Rainwater is a weak acid.

a What can rainwater do to metals like iron?

b What can rainwater do to rocks like limestone?


7Fc/5 Which gas is

which?

7

F

c

knowledge, presenting, researchS

1 The table describes some common gases and the names of some gases arelisted below. Copy the table, and write the names of the gas in the left-handcolumn of the table. You may need to look up the gases in a science textbook, or on the internet.

argon carbon dioxide helium methane nitrogennitrogen dioxide oxygen

?

Gas Properties

This gas is in the air we breathe out.It puts flames out. It turns limewater milky.

This is the gas we need to stay alive. It is also needed for burning.A burning splint will burn brightly in this gas.

This is a brown gas with a strong smell. It is poisonous.It can cause acid rain.

This gas makes up most of the air. It does not react very much.A burning splint will go out in this gas.

This is the gas in the gas taps. It comes from under the North Sea.It burns with a blue flame if there is plenty of air.

This gas does not react at all. It is used in light bulbs so that themetal in the light bulb can get very hot without burning.

This gas is very light, so we use it in balloons. It does not react at all, and will put out a flame. Divers use this gas.

Gas Amount in the air

nitrogen 78%

oxygen 21%

argon 0.9%

other gases (including helium,methane and carbon dioxide) 0.1%

Draw a pie chart to show the composition of the air. You can draw it by hand using a compass and protractor, or you can use a computer program to plot the pie chart for you. Colour in the sections on your pie chart andprovide a key.

2 The next table shows how much of each gas there is in the air.


7Fc/6 Using limestone

7

F

c

Limestone often occurs in areas of great natural beauty. Limestone caves attract manyvisitors, and potholing has become a popular activity. Limestone is used as a buildingmaterial for houses and walls. Limestone chippings can be mixed with tarmac fordriveways, or used for paths. Limestone can also be used as a raw material to makeother chemicals.

The chemical name for limestone is calcium carbonate. When this is heated strongly,it splits up like this:

calcium carbonate Æ calcium oxide (solid) + carbon dioxide (gas)

Calcium oxide is sometimes called ‘quicklime’ or ‘lime’. Gardeners and farmers add itto the soil to make it less acidic. Calcium oxide is also used to make cement. TheEgyptians and Romans used cement for their buildings. They used ‘lime kilns’ to make the calcium oxide and, even today, lime kilns are still used. These days we use most of our cement to make concrete.

Calcium oxide reacts strongly with water toproduce calcium hydroxide, sometimescalled ‘slaked lime’. If you use lots of water,the calcium hydroxide dissolves to givelimewater. When you bubble carbondioxide gas through limewater you get amilky white precipitate:

calcium hydroxide + carbon dioxide Æ calcium carbonate + water

The reaction has gone full circle – back to calcium carbonate again!

calcium carbonate

(limestone)

calcium oxide

(quicklime)

calcium hydroxide

(slaked lime)

1 3

2


1 What is the chemical name of: a limestone? b quicklime? c slaked lime?

2 Are there many buildings made of limestone where you live? Explain why orwhy not.

3 Look at the reaction flowchart. Which reaction:

a needs water? b needs CO2? c uses strong heat?

4 Write a word equation for the reaction in which ‘slaked lime’ is made.

5 a What fuel might the Romans have used for their lime kilns?

b How might we heat a lime kiln today?

c Why would we not use the same fuel as in ancient times?

6 Some campaigners suggest we reduce the amount of limestone that we digup, because it damages the natural environment. What do you think?

?


Page 1 of 2

7Fd/1 Burning copper 1

7

F

d

Name Class

Copper is a metal which reacts with the oxygen in the air when it is heated strongly.

Prediction

I think that if I weigh a piece of copper and then heat it strongly in the air, the mass of

the piece of metal will (stay the same/go up/go down).

I think this because

.

Method

1 Collect a piece of copper foil and weigh it accurately on a top pan balance.Record the mass in the first column of the table.

2 Look carefully at the surface of the piece of copper and write down what itlooks like.

3 Measure the size of your piece of copper metal in mm and record it in the table.

4 Now hold the piece of metal in a pair of metal tongs, and heat it strongly inthe flame of a Bunsen burner for about 3 minutes.

5 After 3 minutes, place the piece of copper onto the heat-proof mat and let itcool down (be careful that none of the copper or any other chemical falls off!).

6 When it is cool, find the new mass of the copper metal and complete the lastcolumn of the table.

PApparatus� Bunsen burner � Heat-proof mat� Tongs � Copper foil� Ruler � Eye protection


of 2


7Fd/1 Burning copper 1 (continued)

7

F

d

predicting, observing, consideringS


Complete the table to show your results.

Observations Before experiment After experiment

Mass of copper metal (g)

Shiny/not shiny

Colour of copper metal

Texture of surface of metal

Size of copper metal(mm x mm)


From my results I can see that after I had heated the copper metal the mass had

(gone up/stayed the same/gone down).

I think this happened because:

.


7Fd/2 Burning copper 2

7

F

d

Copper is a metal which reacts with the oxygen in the air when it is heated strongly.This experiment will help you to check that you understand what happens whensomething reacts with oxygen.

Prediction

1 What do you think will happen to the mass of a piece of copper metal when it isheated? Explain your prediction.

Considering your results

2 What has happened to the mass of the piece of metal?

3 Was this what you expected? Why do you think you got this result?

4 Collect the results from other groups in your class. Have they found the same thinghas happened? Did anyone get a different result? Why do you think this was?

5 Did everybody have the same sized piece of copper to start with? Was this fair?Does it matter if all the pieces are not the same size?

Evaluation

6 If you tried burning a different metal, would you carry out the experiment in thesame way as you did for the copper, or is there anything you would like to change?If so, what would you change and why?

Method

1 Collect a piece of copper foil, measure it and find its mass accurately on a toppan balance. Record the mass and size of the piece of copper.

2 Look carefully at the surface of the piece of copper and record yourobservations.

3 Hold the piece of metal in a pair of metal tongs, and heat it strongly in theflame of a Bunsen burner for about 3 minutes.

4 After 3 minutes, place the piece of copper onto the heat-proof mat and let itcool down (be careful that none of the copper or any other chemical falls off!).

5 When it is cool, find its mass again, re-examine the surface and record your observations.

PApparatus� Bunsen burner � Heatproof mat� Tongs � Copper foil� Ruler � Eye protection


predicting, observing, considering, evaluatingS


7Fd/3 A model fire

extinguisher 1

7

F

d

Page 1 of 2

Name Class

Some fire extinguishers work by releasing a stream of carbon dioxide gas. Carbondioxide is released when sodium hydrogencarbonate powder reacts with dilutesulphuric acid.

You are going to carry out an investigation to find out how much of each chemical isneeded to produce the largest amount of carbon dioxide.

P

Method

1 Measure 0.2 g of sodium hydrogencarbonate, and put it in the conical flask.

2 Set up the rest of the apparatus. Make sure the measuring cylinder is full ofwater and that it is standing upside down over the hole in the shelf. You mayneed to hold it in place, or to use a clamp and stand.

3 Measure the volume of sulphuric acid shown in the table on page 2.

4 Pour the acid into the conical flask, and put the bung in the top. Collect thegas produced in the measuring cylinder.

5 Write down the volume of gas produced in the table on page 2.

6 Wash out the conical flask and then repeat steps 1 to 5 for the other volumesof acid in the table.

Apparatus� Sodium hydrogencarbonate � Sulphuric acid� Large measuring cylinder � Trough� Small measuring cylinder � Shelf� Bung and delivery tube � Conical flask� Eye protection � Clamp and stand

�Wear eye

protection.

sodiumhydrogencarbonateand

Label the diagram using words from the apparatus list.


Page 2 of 2

7Fd/3 A model fire extinguisher 1

(continued)

7

F

d

Recording your resultsRecord your results in this table.

Mass of calcium carbonate Volume of acid Volume of carbon dioxide

used (g) (cm3) (cm3)

0.2 g 5

0.2 g 10

0.2 g 15

0.2 g 20

0.2 g 25

0.2 g 30

0.2 g 35

0.2 g 40

0.2 g 45

0.2 g 50


Plot a graph to show your results. Use axes like this.

Look at your results carefully. Can you see a pattern? If so, what is it?

How much dilute acid should you use with 0.2 g of sodium hydrogencarbonate to makethe most carbon dioxide?

Why did you choose this volume of acid?

Evaluation

Is there any way you could have improved your investigation?

Volume of acid (cm3)

Volu

me

of

CO

2 (

cm3)

observing, presenting, considering, evaluatingS

of 2


7Fd/4 A model fire

extinguisher 2

7

F

d

Some fire extinguishers work by releasing a stream of carbon dioxide gas. Carbon dioxideis released when sodium hydrogencarbonate powder reacts with dilute sulphuric acid.

You are going to carry out an investigation to find out how much of each chemical isneeded to produce the largest amount of carbon dioxide.

P Apparatus� Sodium hydrogencarbonate � Sulphuric acid� Large measuring cylinder � Trough� Small measuring cylinder � Shelf� Bung and delivery tube � Conical flask� Eye protection � Clamp and stand

�Wear eye

protection.

sodiumhydrogencarbonateandsulphuric acid

conical flask

delivery tube small measuring cylinder

largemeasuringcylinder

water

shelf

Planning

1 Decide what you are going to investigate. You could investigate the effect of:

• the mass of sodium hydrogencarbonate

• the volume of sulphuric acid

• the concentration of sulphuric acid.

2 Write a plan for your investigation. Remember to say:

• how you will make sure that you are carrying out a fair test

• which variable you are investigating

• how many times you will carry out the experiment

• how much of each chemical you will use.


Page 2 of 2

7Fd/4 A model fire extinguisher 2

(continued)

7

F

d

planning, observing, presenting, considering, evaluatingS

3 Show your plan to your teacher before you start.


4 Plot a graph to show your results. The quantity (or concentration) of the chemicalyou were investigating should go on the horizontal axis, and the volume of carbondioxide should go on the vertical axis.


5 Look at your results carefully. Can you see a pattern? If so, what is it?

6 How much dilute acid and sodium hydrogencarbonate should you use to make themost carbon dioxide?

Evaluation

7 Is there any way that you could improve your experiment if you had time to do itagain?

8 Is there anything else that you could investigate to try to make the most carbondioxide from your chemicals?


Cut out the cards below and arrange them so that they describe the three types of reaction you have learnt about so far in this unit. When you have put the cardsinto groups:

• stick the cards into your book in their correct groups so that they describe the types of reaction

• or write one or two sentences for each type of reaction, and include all the wordson the cards.

revisionS

7Fd/5 Reaction cards

7

F

d

acid acid carbon dioxide

carbonate hydrogen metal

metal oxide oxygen

product product product

reactants reactants reactants


7Fd/6 Putting out fires

7

F

d

knowledgeS

Type of fire How to put out the fire Which is removed: heat/fuel/oxygen?

(it may be more than one of these)

chip pan

fire

aeroplane

fire

electrical

fire

forest fire

1 Copy and complete these sentences using words from the box. You may need to usesome words more than once.

When things burn they react with from the air. When a metal

it forms a new chemical called an . When magnesium

burns it forms a chemical called oxide.

Fuels are chemicals which can be burned to give . Wood,

, petrol and gas are all fuels. The fire tells

us that all fires need , and oxygen. If one of these is

removed or runs out, the will go out.

2 The table below describes four different fires. For each fire, say how it should be put outsafely and whether the heat, the fuel or the oxygen is removed when the fire is put out.

If you put ‘fire extinguisher’ in the second column, you must say whether it is a waterfire extinguisher, a powder fire extinguisher or a carbon dioxide gas fire extinguisher.

Name Class

burns coal fire fuel heat magnesium natural oxide oxygen triangle


7Fd/7 Fireworks

7

F

d

Fireworks contain mixtures of chemicals. Different colours and explosions areobtained by using different combinations of chemicals and different shaped containers.A firework is just like any other fire: it still needs heat, fuel and oxygen, and it stillproduces products which are oxides.

literacy, knowledgeS

1 Where does the heat come from when a firework is set off?

2 The sparks from a sparkler are tiny pieces of burning iron.

a Where does the oxygen come from that is reacting with the iron?

b Write a word equation for the reaction.

3 Very bright fireworks are often made using magnesium. Write a wordequation to show what happens when magnesium burns.

?

Once a firework is lit the chemical reaction starts. Like all chemical reactions, once afirework has started it can be very difficult to stop. The firework contains the oxygenit needs to burn, as part of the chemicals inside the tube. Once the flame has goneinto the tube of chemicals, they start to release this oxygen. When enough oxygen hasbeen released the firework will ‘go off’. This reaction is happening inside the tube ofthe firework, so there is no way to know when the firework will go off. Once afirework has started to react it is very difficult to stop it – it will keep burning until allthe chemicals have reacted.

4 Where does the oxygen come from for the firework to burn?

5 Why is it dangerous to return to a firework if you think the flame mighthave gone out?

6 Why should fireworks be stored in a closed tin box until they are taken outto be lit?

7 Why is it difficult to put out a firework once it has started to react?

8 Fireworks cause hundreds of severe injuries and even deaths every year.Produce a poster, explaining why fireworks are dangerous. Remember to usethe fire triangle to explain how they can be kept and used safely.

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Page 1 of 2

7Fd/8 A closer look at a

chemical reaction

7

F

d

heat

This experiment was set up to find out what happens when copper is heated in air.Some powdered copper was put into a tube. The mass of the tube was measured. Thetube was then heated.

The air in the syringes was passed over the copper while it was being heated like this.

heat

Each time air was passed over the copper, the volume of air in the syringe was measured.

At the end of the experiment the copper had changed colour from brown to black, andthe mass of the tube was measured again.

Number of passes Volume of gas (cm3)

0 (start) 100

1 92

2 87

3 84

4 82

5 81

6 81

7 80

8 80

9 80

10 80

ResultsMass of empty tube = 20.54 gMass of tube + copper = 20.66 gMass of tube + copper after heating = 20.69 g

of 2


7

F

d

7Fd/8 A closer look at a chemical

reaction (continued)

knowledge, consideringS

1 Suggest two things that tell you a chemical reaction has taken place.

2 Plot a line graph to show the volume of gas after each pass. Join up thepoints with a smooth curve.

3 Is the reaction finished after four passes of air over the copper? How do youknow?

4 How do you know that the reaction has finished after 10 passes of air?

5 The black solid is called copper oxide. Which gas in the air do you think hasreacted with the copper to form the copper oxide?

6 a Does the mass of the copper go up or down when it reacts?

b Explain why this change occurs.

c If you carefully measured the mass of the whole apparatus, including thesyringes, before and after the experiment, would you expect the mass togo up, go down or stay the same? Explain your answer.

7 Calculate:

a the mass of copper that was used

b the change in mass that took place when the copper was heated

c the percentage change in mass.

?


Page 1 of 2

7Fe/1 Burning fuels 1

7

F

e


Now write the results from your experiment in the table below:

What happens when different fuels burn?

Label the diagram using words from the list below.

delivery tube bung suction pump glass thistle funnel

U-tube large beaker iced water boiling tube

limewater thermometer candle

P

Observation Before experiment After experiment

Appearance of fuel

Appearance of limewater

Appearance of U-tube

Temperature shown on

thermometer (°C)

Name Class

of 2


7Fe/1 Burning fuels 1 (continued)

7

F

e



Use your results, and the words in the box, to help you fill the gaps in thesesentences.

When the fuel was burning, I saw . A chemical

took place and materials were

made. This experiment shows me that burning a

produces and .

It also gives out . The reaction is

because we could not get the back, even if we put the water and

carbon dioxide together again.

water new irreversible carbon dioxide fuel

reaction energy


Page 1 of 2

7Fe/2 Burning fuels 2

7

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e

When a chemical burns, oxygen joins with the atoms in the chemical to form anoxide. This reaction also gives out energy, usually in the form of heat and light. Wecan show that the oxides formed are hydrogen oxide (water) and carbon dioxide bycarrying out an experiment.

Method

1 Record the temperature shown on the thermometer.

2 Record the appearance of the limewater and the U-tube.

3 Turn on the suction pump and place the burning candle under the funnel.

4 Let the fuel burn for 5 minutes or until the limewater has changed.

5 Blow out the flame and record your observations.

6 Repeat steps 1 to 5 for your other fuels, using fresh limewater for each fuel.

P Apparatus� Delivery tubes with bungs � Suction pump � Glass thistle funnel� U-tube � Large beaker � Iced water� Boiling tube � Limewater � Thermometer� Top pan balance � Spatula/teaspoon � Stopwatch� Stand and clamps � Candle (or other fuels to burn)

suction

pump

cold water limewaterconical flaskcandle

funnel

thermometer

of 2


7Fe/2 Burning fuels 2 (continued)

7

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e



2 Was carbon dioxide produced when the fuel was burnt? How do you know?

3 Was water produced when the fuel was burnt? How do you know? How could youtest the liquid to make sure it is water?

4 Why was the U-tube placed in a beaker of iced water?

5 Was heat given out when the fuel burnt? How do you know?

6 Was anything else made during the reaction? Explain your answer.

Evaluation

7 How could you have improved your experiment?


1 Record your results in a table like this one:

Observation Before experiment After experiment

Appearance of limewater

Appearance of U-tube

Temperature shown on

thermometer (°C)


Does a burning candle use up something in the air?

predicting, observing, presenting, considering, evaluatingS

7Fe/3 Burning time

7

F

e

Prediction

1 Before you carry out your investigation, predict how the size of the beaker willaffect the length of time the candle burns. Explain the reasons for your prediction.


2 Design a table to show all the information you will need to record.

Considering your results/conclusions

3 Draw a graph to show your results. You may need to work out the volume of each beaker. Use axes like this:

4 Describe what you have found out.

5 Do your conclusions agree with the prediction you made?

6 Explain your results using scientific ideas.

Evaluation

7 If you had time to do your experiment again, is there anything you could improve?

Method

1 If your beakers have pouring spouts, use alittle plasticine to fill in the gap so that whenyou stand it upside down, no air can get in.

2 Stand your candle on the heatproof mat and light it.

3 Carefully put a beaker over the candle andstart the stopclock.

4 Watch the candle carefully. Stop timingwhen it goes out.

P Apparatus� Candle � Heatproof mat� Stopclock � Plasticine� Different size beakers

�Make sure your candle cannot

fall over. You may need to stickit to the heatproof mat with a

little melted wax.

Plasticine

Volume (cm3)

Tim

e (s

)


Cut out these statements. Choose the statements that help you to summarise what youhave learned in this unit. Arrange the statements in a sensible order, then stick theminto your book, or use them to help you to write your own summary of the unit.

7Fe/4 Reactions summary

7

F

e

A physical change is usually reversible.

Hydrogen explodes with a squeaky ‘pop’ if you put a lighted splintinto it.

You can tell if a reaction has occurred if the temperature or colourchanges, or a gas is given off.

Some metals do not react with acids at all.

Rocks like limestone contain a chemical called calcium carbonate.

Hydrogen is lighter than air, and rises up out of a test tube.

You can see bubbles when an acid reacts with a metal.

Fossil fuels contain carbon, which combines with oxygen from the air when they burn.

The fizz in fizzy drinks is carbon dioxide.

Fossil fuels contain carbon.

Chemicals called carbonates are found in rocks, some cookingingredients, and in some indigestion tablets.

Some metals can burn.

Acids react with some metals to give hydrogen gas.

When acids react with carbonates a gas called carbon dioxide isgiven off.

A chemical reaction is usually irreversible.

Fossil fuels produce carbon dioxide gas and water when they burn.

A chemical reaction makes new materials, called the products ofthe reaction.

When you add an acid to a carbonate you can see bubbles.

When metals burn they form metal oxides.

Carbon dioxide turns limewater milky.



7Fe/5 Reactions

wordsearch

7

F

e

Solve the clues below, then find the answers in the wordsearch grid.

1 The product of the reaction between copper and oxygen.

2 The name given to chemicals which react together.

3 This is released when fuels burn in oxygen.

4 The metal which reacts with oxygen to form magnesium oxide.

5 The name given to new chemicals which are made in a reaction.

6 When a fuel burns, this gas is produced. (It contains carbon.)

7 The other chemical produced when a fuel burns.

8 The oxide formed when zinc reacts with oxygen.

9 Combustion reactions cannot be reversed. They are .

10 This metal forms a black oxide when it is heated.


C A R B O N D I O X I D E

W B E D S U L P S R R E O

A Z A B A C O P P E R O Z

T D C I R F T K U D E G I

E F T K O O L T B O V H N

R M A G N E S I U M E L C

A W N E M E T J W S R E O

X R T P R O D U C T S C X

O F S U Q E G U E A I A I

Z E W L O N S O C C B Q D

D A E T N E H E Q Y L V E

C O P P E R O X I D E J T

D A Y S R G L Y T E A I D

C H I R A Y A B U Q S L F


Name Class

7Fe/6 Word equations for

burning fuels

7

F

e


1 When a candle burns, a chemical reactionhappens.

?

Fill in the boxes and the gaps in the sentences, using words from the list.

+ Æ + (+ )

Ï Ô Ô Ô Ô Ô Ì Ô Ô Ô Ô Ô Ô Ó Ï Ô Ô Ô Ô Ô Ô Ô Ô Ô Ì Ô Ô Ô Ô Ô Ô Ô Ô Ô Ô Ó

reactants products

This type of reaction is called a reaction. It is

(cannot be reversed). The candle wax is the

and oxygen comes from the .

air candle wax carbon dioxide combustion energy

fuel irreversible oxygen water

2 Now complete these word equations for the combustion of different materials.

a wood + Æ + (+ )

b natural gas (methane) + Æ + (+ )

c ethanol + Æ + (+ )

7

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ou

t bu

rnin

g h

ave

chan

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reat

ly o

ver

the

last

300 y

ears

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e Ph

logi

ston

Th

eory

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evel

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rgSta

hl

(1660–1

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was

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he

work

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ph

Pri

estl

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1733–1

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and A

nto

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Lav

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ier

(1743–1

794).

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ur

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rod

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alk

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sep

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✄

10265 7f p242 292 fm gecko - mnwikiks3scienceyear1 - Home€¦ · · 2016-05-24D air, wood, oil 2...

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