C1.3 Metals Booklet

41
AQA GCSE SCIENCE A CHEMISTRY UNIT 2 C1.3 Metals and their uses Extracting metals Alloys Properties and uses of metals

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Workbook for AQA Core Science GCSE C1.3 Metals and their uses

Transcript of C1.3 Metals Booklet

Page 1: C1.3 Metals Booklet

AQA GCSE SCIENCE A CHEMISTRY UNIT 2

C1.3 Metals and their uses Extracting metals

Alloys Properties and uses of metals

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C1.3 Metals and their uses

Summary

Metals are very useful in our everyday lives. Ores are naturally occurring rocks that

provide an economic starting point for the manufacture of metals. Iron ore is used to

make iron and steel. Copper can be easily extracted but copper-rich ores are

becoming scarce so new methods of extracting copper are being developed.

Aluminium and titanium are useful metals but are expensive to produce. Metals can

be mixed together to make alloys.

Students should be able to:

■ consider and evaluate the social, economic and environmental impacts of

exploiting metal ores, of using metals and of recycling metals

■ evaluate the benefits, drawbacks and risks of using metals as structural materials.

Key words Ores

Bauxite

Haematite

Metal

Economical

Extract

Purified

Reduction

Reactivity

Electrolysis

Phytomining

Bioleaching

Displacement

Blast furnace

Alloy

Mixtures

Compounds

Steel

Transition metals

Density

Corrosion

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C1.3.1 Extracting metals a) Ores contain enough metal to make it economical to extract the metal. The economics of extraction may change over time. Two common ores are bauxite (aluminium ore, Al2O3) and haematite (iron ore Fe2O3)

Bauxite Three different types of haematite

b) Ores are mined and may be concentrated before the metal is extracted and purified. c) Unreactive metals such as gold are found in the Earth as the metal itself but most metals are found as compounds that require chemical reactions to extract the metal. d) Metals that are less reactive than carbon can be extracted from their oxides by reduction with carbon. In simple terms reduction is the removal of oxygen:

Al2O3 reduction Al

Fe2O3 reduction Fe

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Iron oxide (haematite) can be reduced with carbon in the blast furnace to make iron as carbon is more reactive than iron. So carbon is able to reduce iron oxide.

e) Metals that are more reactive than carbon, such as aluminium, are extracted by electrolysis of molten compounds. The use of large amounts of energy in the extraction of these metals makes them expensive.

f) Copper can be extracted from copper-rich ores by heating the ores in a furnace (smelting). The copper can be purified by electrolysis. The supply of copper-rich ores is limited.

Copper is extracted from its ores by chemical processes that involve heat or electricity. Copper-rich ores are being depleted and traditional mining and extraction have major environmental impacts.

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g) New ways of extracting copper from low grade ores are being researched to limit the environmental impact of traditional mining. Copper can also be extracted by phytomining, or by bioleaching: • phytomining uses plants to absorb metal compounds when they grow. The plants are burned to produce ash that contains the metal compounds. The metals can then be extracted from the ash. • bioleaching uses bacteria that can live by using the energy of the bond between sulfur and copper. This separates the metal from the ore. It has the advantage that it is very energy efficient typically using only 30% to 50 % of the traditional method. It has the disadvantage that it is very slow. h) Copper can be obtained from solutions of copper salts by electrolysis or by displacement using scrap iron. During electrolysis positive ions move towards the negative electrode (cathode).

i) Aluminium and titanium cannot be extracted from their oxides by reduction with carbon. Current methods of extraction are expensive because:

• there are many stages in the processes • large amounts of energy are needed.

j) We should recycle metals because extracting them uses limited resources and is expensive in terms of energy and effects on the environment

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C1.3.2 Alloys a) Iron from the blast furnace contains about 96% iron. The impurities make it brittle and so it has limited uses. Cast iron is useful because it is strong in compression. b) Most iron is converted into steels. Steels are alloys since they are mixtures (not compounds) of iron with carbon. Some steels contain other metals such as nickel, chromium and tungsten. Alloys can be designed to have properties for specific uses. Low-carbon steels are easily shaped, high-carbon steels are hard, and stainless steels are resistant to corrosion.

Type of steel Percentage of carbon

Uses

Mild steel Up to 0.25% Steel buildings, girders

Medium carbon steel

0.25% to 0.45% Car parts

High carbon steel 0.45% to 1.50% Surgical instruments eg scalpel

c) Most metals in everyday use are alloys. Pure copper, gold, iron and aluminium are too soft for many uses and so are mixed with small amounts of similar metals to make them harder for everyday use.

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C1.3.3 Properties and uses of metals a) The elements in the central block of the periodic table are known as transition metals.

Like other metals they are good conductors of heat and electricity and can be bent or hammered into shape. They are useful as structural materials and for making things that must allow heat or electricity to pass through them easily. b) Copper has properties that make it useful for electrical wiring and plumbing. Copper:

• is a good conductor of electricity and heat • can be bent but is hard enough to be used to make pipes or tanks • it can easily be joined together • does not react with water • it is non-magnetic • it is antibacterial

c) Low density and resistance to corrosion make aluminium and titanium useful metals. Aluminium

1) Low density and strength make aluminium ideal for construction of aircraft,

lightweight vehicles, and ladders. An alloy of aluminium called duralumin is

often used instead of pure aluminium because of its improved properties.

2) Easy shaping and corrosion resistance make aluminium a good material

for drink cans and roofing materials.

3) Corrosion resistance and low density leads to its use for greenhouses

and window frames.

4) Good conduction of heat leads to its use for boilers, cookers and

cookware.

5) Good conduction of electricity leads to its use for overhead power cables

hung from pylons (low density gives it an advantage over copper).

6) High reflectivity makes aluminium ideal for mirrors, reflectors and heat

resistant clothing for fire fighting.

Titanium is 60% heavier than aluminium, but it is much stronger. It is nearly half as light as steel, but it is equally strong.

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1. Metal or non-metal Place the following in the correct column:

Shiny Dull Brittle Ductile Low melting point High melting point Good conductor Poor conductor In Group 0 of the periodic table In Group I of the periodic table Malleable Sonorous Mainly solid at room temperature

Metal Non-metal

2. Explain the meaning of the words in bold Metals occur in the earth as ores. First the ore is dug up and then it has to be concentrated. Then the metal is extracted from the ore using a reducing agent. Ore

……………………………………………………………………………………………..

……………………………………………………………………………………………..

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Concentrated

……………………………………………………………………………………………..

……………………………………………………………………………………………..

Reducing agent

……………………………………………………………………………………………..

……………………………………………………………………………………………..

3. For each of these – state if the metal will reduce the oxide

a. Aluminium v magnesium oxide

b. Magnesium oxide v iron

c. Iron oxide v aluminium

d. Carbon v aluminium oxide

e. Iron oxide v carbon

4. Metal X will reduce aluminium oxide but not calcium oxide.

Use the resistivity series to identify X.

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5. Metal Y will reduce copper oxide but not iron oxide – which possible metals could

it be?

6. Which of the following metals are found in the Earth as an element and not a

compound? Circle the correct answer:

Magnesium Gold Copper Tin Iron

7. Which of the following metals could not be extracted from its ore with carbon?

Circle the correct answer

Zinc Tin Copper Aluminium Iron

8. Steel is an alloy of iron.

What does the term alloy mean?

……………………………………………………………………………………………..

……………………………………………………………………………………………..

9. Why does pure iron have fewer uses than steel?

……………………………………………………………………………………………..

……………………………………………………………………………………………..

10. Why are alloys usually harder than pure metals?

……………………………………………………………………………………………..

……………………………………………………………………………………………..

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11. Give four reasons why copper often used for electrical wiring and for plumbing?

1. ……………………………………………………………………………………

2. ……………………………………………………………………………………

3. ……………………………………………………………………………………

4. ……………………………………………………………………………………

12.

Aluminium is often used for saucepans.

Name two properties of aluminium that make

it suitable for saucepans.

1. ……………………………………………………………………………………

2. ……………………………………………………………………………………

13. Why is aluminium used rather than copper for overhead

electrical power cables?

……………………………………………………..

……………………………………………………..

……………………………………………………..

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14. Match the properties of aluminium to its uses. The property can be used more

than once.

Low density Overhead power cables

Strength Cookware

Corrosion resistance Drink cans

Low density Ladders

Good conductor of heat Heat resistant clothing for fire fighting

Good conductor of electricity Mirrors

High reflectivity Window frames

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Slides from the YouTube video via www.my-gcsescience.com

Name an ore of iron ……………………………………….

Name an ore of aluminium ………………………………………

Gold is often extracted from ores that contain very small percentages of the metal,

but iron is only extracted from ores with a large percentage of the metal. Explain why.

………………………………………………………………………………………………

………………………………………………………………………………………………

………………………………………………………………………………………………

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Copper – extraction methods

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Iron, steel and other alloys

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Transition metals

Which of these metals is not a

transition metal?

Copper Iron Aluminium Titanium

Which metals would be best for and why:

1. Saucepan base metal: …………………………………………………..

Reason 1

……………………………………………………………………………………….

Reason 2

…………………………………………………………………………………….

Car bodies metal: …………………………………………………..

Reason 1

……………………………………………………………………………………….

Reason 2

………………………………………………………………………………………….

3. Artificial hip joint

base metal: …………………………………………………..

Reason 1

……………………………………………………………………………………….

Reason 2

…………………………………………………………………………………….

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Impact of metal extraction

Social Economic Environmental

Advantage

Disadvantage

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GCSE Science A Chemistry Metals

Q1. Copper metal is used for electric wires. An alloy of copper, called brass, is used for pins and terminals of electric plugs.

(a) Copper metal is relatively soft and flexible.

Give another reason why copper is used for electric wires.

....................................................................................................................................

.................................................................................................................................... (1)

(b) Brass is an alloy.

What is an alloy?

....................................................................................................................................

.................................................................................................................................... (1)

(c) Open-cast mining of copper ore makes a very large hole.

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(i) Suggest one environmental problem that is caused by open-cast mining of copper ore.

..........................................................................................................................

.......................................................................................................................... (1)

(ii) Some copper ores contain copper sulfide, CuS.

Copper sulfide is heated in air to produce copper and sulfur dioxide.

CuS + O2 → Cu + SO2

Suggest one environmental problem caused by heating copper sulfide in air.

..........................................................................................................................

.......................................................................................................................... (1)

(d) The amount of copper-rich ores is estimated to last only a few more years. New houses need several kilometres of copper wire.

(i) Explain why the need to use so much copper will cause a problem in the future.

..........................................................................................................................

.......................................................................................................................... (1)

(ii) Suggest two ways in which society could overcome this problem.

1 .......................................................................................................................

..........................................................................................................................

2 .......................................................................................................................

.......................................................................................................................... (2)

(Total 7 marks)

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Q2. This is a headline from a newspaper.

‘Why is a 2p coin made in 1991 now worth 3.3p?’

(a) The bar chart shows the percentages of metals in UK coins in 1991.

Use the bar chart to answer these questions.

(i) Which metal is in all of these coins? ................................................... (1)

(ii) Which coin does not contain zinc? ...................................................... (1)

(iii) What is the percentage of nickel in a 50p coin? ............................... % (1)

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(b) Suggest two reasons why a 2p coin made in 1991 is now worth 3.3p.

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................ (2)

(Total 5 marks)

Q3. Cassiterite is an ore of the metal tin.

(a) What is an ore?

....................................................................................................................................

.................................................................................................................................... (2)

(b) Some metals are obtained by removing oxygen from the metal oxide.

What name do we give to this chemical reaction?

.................................................................................................................................... (1)

(c) Name one metal which must be extracted from its melted ore by electrolysis rather than by using carbon.

.................................................................................................................................... (1)

(Total 4 marks)

Q4. Copper metal can be extracted from a solution of copper(II) chloride.

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Copper chloride is an ionic compound.

State where the copper would collect and explain your answer fully.

...............................................................................................................................................

...............................................................................................................................................

............................................................................................................................................... (Total 2 marks)

Q5. Copper is a widely used metal. The main ore of copper contains copper sulfide. Copper can be extracted from copper sulfide in a three stage process.

(a) In the first stage of extraction the copper sulfide is heated in air.

(i) Balance the symbol equation for the reaction.

Cu2S + ........O2 → .........CuO + SO2 (1)

(ii) Explain why there would be an environmental problem if the gas from this reaction were allowed to escape into the atmosphere.

..........................................................................................................................

..........................................................................................................................

.......................................................................................................................... (2)

(b) In the second stage copper oxide, CuO, is reduced using carbon.

Describe and explain what happens during this reaction.

....................................................................................................................................

....................................................................................................................................

.................................................................................................................................... (2)

(c) During the third stage the copper can be purified as shown in the diagram.

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(i) What is the name of the type of process used for this purification?

.......................................................................................................................... (1)

(ii) Give one use of purified copper.

.......................................................................................................................... (1)

(d) Copper-rich ores are running out.

New ways of extracting copper from low grade ores are being researched.

Recycling of copper may be better than extracting copper from its ores.

Explain why.

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(Total 10 marks)

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Q6. Iron ore is the main source of iron.

(a) This was the headline in a newspaper.

‘Village protests against quarry’

The dotted line (---- ) on the map is drawn around the area from which a company wants to quarry iron ore.

(i) Give one reason that the company could give for the need to quarry the iron ore.

..........................................................................................................................

.......................................................................................................................... (1)

(ii) The people who live in the village do not want the quarry because it would decrease the value of their homes.

Suggest two other reasons why the villagers do not want the quarry.

1 .......................................................................................................................

..........................................................................................................................

2 .......................................................................................................................

.......................................................................................................................... (2)

(b) Iron ore contains the compound iron oxide, Fe2O3.

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(i) Iron is extracted from its oxide in the blast furnace.

Complete the word equation for the extraction of iron.

iron oxide + ............................................................... → iron + carbon dioxide (1)

(ii) This diagram represents pure iron.

Use the diagram to explain why pure iron is described as an element.

..........................................................................................................................

..........................................................................................................................

.......................................................................................................................... (2)

(iii) Pure iron is relatively soft. The iron from the blast furnace is hard and brittle. The diagram below represents iron from the blast furnace.

Use the diagram to explain why iron from the blast furnace is hard and brittle.

..........................................................................................................................

..........................................................................................................................

.......................................................................................................................... (2)

(Total 8 marks)

Q7. Many everyday items are made from iron.

(a) Haematite is an ore of iron. Haematite contains iron oxide, Fe2O3.

(i) What is the meaning of the term ore?

...........................................................................................................................

...........................................................................................................................

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(1)

(ii) Iron can be produced by reacting iron oxide with carbon in a blast furnace.

What type of reaction produces the iron?

...........................................................................................................................

........................................................................................................................... (1)

(iii) The word equation for this reaction is:

iron oxide + carbon → iron + carbon dioxide

Complete and balance the symbol equation for this reaction.

.....Fe2O3 + .....C → ................... + ................... (2)

(b) Pure iron is relatively soft and not very strong.

The iron from the blast furnace is very hard and brittle. It contains about 4% carbon and is used as cast iron.

Explain the differences in the properties of pure iron and cast iron by referring to the diagrams.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (3)

(c) The diagram shows the way in which iron is extracted, used and recycled.

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Explain why the recycling of iron is necessary for sustainable development.

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(Total 10 marks)

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Q8. Aluminium has many uses because of its low density, good electrical conductivity, flexibility and resistance to corrosion.

The main steps in the extraction of aluminium are shown in the flow chart.

(a) Use the information in the flow chart to suggest the benefits of recycling aluminium.

....................................................................................................................................

....................................................................................................................................

....................................................................................................................................

....................................................................................................................................

.................................................................................................................................... (3)

(b) Pure aluminium is rarely used for the construction of large objects. Small amounts of other metals are usually mixed with aluminium.

Explain why.

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....................................................................................................................................

....................................................................................................................................

.................................................................................................................................... (2)

(Total 5 marks)

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Q9. Use the Reactivity Series of Metals on the Data Sheet to help you to answer this question.

The table gives information about the extraction of some metals.

Metal Date of discovery Main source Main extraction method

Gold Known to ancient civilisations

In the Earth as the metal itself

Physically separating it from the rocks it is mixed with

Zinc 1500 Zinc carbonate Reduction by carbon

Sodium 1807 Sodium chloride Electrolysis

(a) Explain why gold is found mainly as the metal itself in the Earth.

.....................................................................................................................................

..................................................................................................................................... (1)

(b) One of the reactions involved in producing zinc is represented by this equation.

ZnO + C → Zn + CO

Explain why carbon can be used to extract zinc.

.....................................................................................................................................

..................................................................................................................................... (1)

(c) Sodium is one of the most abundant metals on Earth.

Explain, as fully as you can, why sodium was not extracted until 1807.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)

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Q10. The demand for iron and steel is high.

(a) Iron that is extracted from its oxide by carbon reduction in a blast furnace is called cast iron. Cast iron contains about 4% carbon. This carbon makes cast iron very brittle.

Carbon steels can be made by the following processes.

• Blowing oxygen into molten cast iron to remove most of the carbon. • Adding a calculated amount of carbon.

Sometimes different metals may also be added to the molten carbon steels.

(i) Suggest how blowing oxygen into molten cast iron removes most of the carbon.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

........................................................................................................................... (2)

(ii) Why are different metals sometimes added to molten carbon steels?

...........................................................................................................................

........................................................................................................................... (1)

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(b) The percentage of iron and steel recycled in the UK has been increasing.

Year %iron and steel recycled

1998 25

2000 35

2002 42

2004 46

2006 57

The UK government has set targets for the percentage of iron and steel to be recycled. In 2006 the target was exceeded.

Suggest two reasons why the UK government wants to encourage recycling of iron and steel.

1 ..................................................................................................................................

.....................................................................................................................................

2 ..................................................................................................................................

..................................................................................................................................... (2)

(Total 5 marks)

Q11. Copper is found in the Earth’s crust as an ore containing copper sulfide. Large areas of land, where this ore was once quarried, are contaminated with low percentages of copper sulfide. Copper would be too expensive to extract from this contaminated land using the traditional method of quarrying and then heating in a furnace.

(a) The percentage of copper ore in the contaminated land is low.

(i) It would be too expensive to extract from this land by the traditional method.

Explain why.

...............................................................................................................

............................................................................................................... (1)

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(ii) Extracting copper from this land by the traditional method would have a major environmental impact.

Give one reason why.

...............................................................................................................

............................................................................................................... (1)

(b) One way to extract the copper from land that contains low percentages of copper sulfide is by bioleaching. Bioleaching uses bacteria. The bacteria produce a solution of copper sulfate.

It is possible to get copper from a solution of copper sulfate using scrap iron.

(i) It is economical to use scrap iron to get copper.

Give one reason why.

...............................................................................................................

............................................................................................................... (1)

(ii) Why can iron be used to get copper from copper sulfate solution?

...............................................................................................................

............................................................................................................... (1)

(c) A new way to extract the copper from land that contains low percentages of copper sulfide is phytomining.

Phytomining uses plants. Plants are grown on this land and absorb copper compounds through their roots.

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(i) Use this information to give two advantages of phytomining compared to the traditional method.

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............................................................................................................... (2)

(ii) Use this information to suggest one disadvantage of phytomining compared to the traditional method.

...............................................................................................................

............................................................................................................... (1)

(Total 7 marks)

Q12. The table gives information about some metals.

Name of the metal Cost of one tonne of the metal in December 2003 (£)

Percentage of the metal in the crust of the earth

(%)

Aluminium 883 8.2

Platinum 16720000 0.0000001

Iron 216 4.1

Gold 8236800 0.0000001

(a) Use information in the table to suggest why gold and platinum are very expensive metals.

.....................................................................................................................................

..................................................................................................................................... (1)

(b) Aluminium and iron are made by reduction of their ores.

(i) Name the element that is removed from the ores when they are reduced.

........................................................................................................................... (1)

(ii) Use the reactivity series on the Data Sheet to suggest a metal that would reduce

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aluminium ore.

........................................................................................................................... (1)

(c) Aluminium is made by the reduction of molten aluminium ore, using a very large amount of electricity.

(i) How is iron ore reduced in a blast furnace to make iron?

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

........................................................................................................................... (2)

(ii) Suggest why aluminium is more expensive than iron.

...........................................................................................................................

........................................................................................................................... (1)

(Total 6 marks)

Q13. Most metals are extracted from ores, which are mined from the Earth’s crust.

In a blast furnace coke is heated in air to form carbon dioxide.

(a) (i) Give the symbol equation for this reaction.

............................................................................................................. (1)

(ii) The carbon dioxide then reacts with more coke.

Write a balanced symbol equation for this reaction.

............................................................................................................. (2)

(b) The chemical equation shows a reaction that occurs when iron is produced.

Fe2 O3 + ..... CO ......Fe + ...... CO2

(i) Balance the equation above by writing the correct numbers in the spaces in the equation.

(2)

(ii) Complete the sentences about the reaction.

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The name of the compound that is being reduced in this reaction is

.............................................................................................................

The name of the substance that is the reducing agent is

............................................................................................................. (2)

(c) (i) Some metals can not be extracted from their ores by heating with carbon. These metals are extracted by electrolysis.

Name one metal that is extracted by electrolysis.

............................................................................................................. (1)

(ii) Suggest two reasons why metals extracted by electrolysis are often more expensive than iron.

1. .........................................................................................................

.............................................................................................................

2. .........................................................................................................

............................................................................................................. (2)

(Total 10 marks)

Q14. Some objects can be electroplated (coated with metals).

The diagram shows how a key can be electroplated. The key and the metal used for electroplating are used as the electrodes.

(a) Name electrodes A and B.

A ...................................................................................................................

B ................................................................................................................... (2)

(b) Use the diagram to explain what happens to the atoms in the metal of electrode B used for electroplating during electrolysis.

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(c) Use the diagram to explain how the key becomes electroplated with the metal used for electroplating.

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...................................................................................................................... (3)

(Total 9 marks)

Q15. The diagram shows a circuit that is used in a torch. Electrons flow through this circuit.

(a) Why is copper used for the wire?

..................................................................................................................................... (1)

(b) The diagram shows the structure of an atom of lithium.

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Name the particle labelled Z.

..................................................................................................................................... (1)

(c) The table shows some properties of the metals used in the electrical circuit.

Metal Melting point in

°C Boiling point in

°C Reaction with oxygen

Copper 1083 2582 Reacts slowly to form a thin oxide layer on surface

Lithium 179 1317 Reacts rapidly to form oxide

Tungsten 3370 5930 Reacts only when very hot to form oxide

(i) Use information from the table to suggest the order of reactivity for copper, lithium and tungsten.

most reactive ..........................................................

..........................................................

least reactive .......................................................... (2)

(ii) The filament wire glows because it gets very hot.

Use information from the table to suggest one reason why tungsten is used for the filament wire in the light bulb.

...........................................................................................................................

........................................................................................................................... (1)

(d) The gas used in the light bulb is argon.

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Draw a ring around the correct word in the box to complete the sentence.

Argon is used in the light bulb because it is

dense.

solid.

unreactive.

.

(1)

(Total 6 marks)

Q16. Copper is found in the Earth’s crust as an ore containing copper sulfide. Large areas of land, where this ore was once quarried, are contaminated with low percentages of copper sulfide. Copper would be too expensive to extract from this contaminated land using the traditional method of quarrying and then heating in a furnace.

(a) Extracting copper from this land by the traditional method would have a major environmental impact.

Give two reasons why.

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................ (2)

(b) One way to extract the copper from land that contains low percentages of copper sulfide is by bioleaching. Bioleaching uses bacteria. The bacteria produce a solution of copper sulfate.

It is possible to get copper from a solution of copper sulfate using scrap iron.

(i) It is economical to use scrap iron to get copper.

Give one reason why.

..............................................................................................................

.............................................................................................................. (1)

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(ii) Iron can be used to get copper from copper sulfate solution.

Explain why.

..............................................................................................................

..............................................................................................................

..............................................................................................................

.............................................................................................................. (2)

(Total 5 marks)

Q17. Nearly all zinc is obtained from ores that also contain lead. The metals zinc and lead can be extracted by reducing their oxides using carbon.

(a) Complete the following sentence.

Zinc oxide is reduced by carbon, which takes away ............................................... to leave zinc metal.

(1)

(b) The melting points and boiling points of lead and zinc are given in the table.

Metal Lead Zinc

Melting point in °C 328 420

Boiling point in °C 1740 907

Density in g per cm3 11.34 7.14

The furnace operates at a temperature of 1200 °C.

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(i) Explain why only lead metal remains in the furnace.

..............................................................................................................

..............................................................................................................

.............................................................................................................. (2)

(ii) Suggest how zinc can be separated from the lead in the condenser.

..............................................................................................................

..............................................................................................................

.............................................................................................................. (2)

(Total 5 marks)

Q18. The hip joint between the femur and pelvis sometimes has to be replaced. Early hip replacement joints were made from stainless steel.

Stainless steel is an alloy of iron, chromium and nickel.

The diagram below represents the particles in stainless steel.

(a) Use the particle diagram to complete the percentages of metals in this stainless steel.

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The first one has been done for you.

Element Percentage (%)

Iron, Fe 72

Chromium, Cr

Nickel, Ni

(2)

(b) Pure iron is a relatively soft, metallic element.

(i) Why is iron described as an element?

...........................................................................................................................

........................................................................................................................... (1)

(ii) Suggest why pure iron would not be suitable for a hip replacement joint.

...........................................................................................................................

........................................................................................................................... (1)

(iii) Use the particle diagram to help you to explain why stainless steel is harder than pure iron.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

........................................................................................................................... (2)

(Total 6 marks)