C1.3 Metals and their uses

Question 1

Define ‘ore’

Answer 1

A rock containing enough metal to make it economically worthwhile extracting

Question 2

What happens to ores before the metal is extracted?

Answer 2

• Mined

- Concentrated

Question 3

How might the economics of extraction change over time?

Answer 3

• If the market price decreases, it might not be worth extracting it
• If the market price increases, it might be worth extracting more of it
• As technology improves, it becomes possible to extract more metal than was originally possible.

Question 4

How are metals usually found in the earth?

Answer 4

As compounds - oxides of the metals - that need chemical reactions to extract the metals

Question 5

Why are some metals found in the earth as the metal itself?

Answer 5

They are unreactive e.g gold

Question 6

What is the ore of aluminium?

Answer 6

Bauxite

Question 7

What is the ore of copper?

Answer 7

Chalcopyrite

Question 8

What is the ore of iron?

Answer 8

Haematite

Question 9

What is the ore of titanium?

Answer 9

Rutile

Question 10

Define ‘reduction’

Answer 10

A chemical reaction in which oxygen is removed

Question 11

Which metals can be reduced with carbon?

Answer 11

Metals less reactive than carbon

Question 12

What is the process of reaction with carbon?

Answer 12

The ores are reacted with carbon to remove the oxygen in them e.g
iron oxide (haematite) + carbon ===> iron + carbon dioxde

Question 13

Explain how iron oxide is reduced in a blast furnace.

Answer 13

• Iron oxide, limestone and coke are put in the top of the blast furnace
• Hot air is blown in at the bottom
• Carbon monoxide reduces the iron core (at high temperatures carbon dioxide in the air reacts to form carbon monoxide)
• Molten slag and iron come out at the bottom

Question 14

How are metals more reactive than carbon extracted?

Answer 14

With electrolysis of their molten compounds

Question 15

Give an example of a metal extracted with electrolysis.

Answer 15

aluminium from aluminium oxide (bauxite)

Question 16

Why is electrolysis expensive?

Answer 16

A high temperature is needed to melt the metals, which uses a high amount of energy

Question 17

What is smelting?

Answer 17

Heating a copper ore in a furnace to reduce it with carbon

Question 18

Why does copper undergo electrolysis after smelting?

Answer 18

To purify it so that it can conduct electricity

Question 19

What is electrolysis?

Answer 19

The breaking down of a substance using electricity

Question 20

What is the electrolyte and what is it usually made of?

Answer 20

The liquid that conducts the electricity in electrolysis, it’s usually made of molten metal oxides or a metal salt solution from the ore.

Question 21

What is an important property of the electrolyte and why?

Answer 21

It contains free ions, they conduct electricity and allow the whole thing to work

Question 22

What happens at the anode in the electrolysis of copper?

Answer 22

Electrons are taken away from the copper ions, causing them to become copper positive ions

Question 23

What happens at the cathode in the electrolysis of copper?

Answer 23

The copper ions gain electrons and become copper atoms again.

Question 24

What is displacement?

Answer 24

A reaction where a more reactive metal replaces a less reactive one in a dissolved metal compound.

Question 25

Why does displacement happen?

Answer 25

The more reactive metal bonds more strongly to the non-metal part and pushes out the less reactive metal.

Question 26

How is copper displaced?

Answer 26

Using scrap iron - useful because its cheap Its put in a solution of copper sulfate: copper sulfate + iron ==> iron sulfate + copper

Question 27

Why is important to recycle copper?

Answer 27

- The supply of copper rich ores is limited | - The demand for copper is growing

Question 28

What are scientists looking into to supply the demand for copper?

Answer 28

- Ways of extracting copper from low grade ores | - Ways of extracting copper from the waste produced from copper extraction

Question 29

Explain bioleaching

Answer 29

- Bacteria separate copper from copper sulfide - They get energy from breaking the bond between the copper and the sulfur - The leachate (solution) they produce from this process contains copper which is extracted

Question 30

Explain phytomining

Answer 30

- Plants absorb copper compounds through their roots in copper rich soil - The plants can't use the copper so it builds up in the leaves and roots - The plants are then harvested, dried and burnt in a furnace - The copper is collected from the ash

Question 31

Why are the current methods of extracting aluminum and titanium expensive?

Answer 31

- There are many stages involved | - Large amounts of energy are needed

Question 32

What are the advantages of extracting metals?

Answer 32

- Useful products - Local people have jobs - Improves the area's economy

Question 33

What are the disadvantages of extracting metals?

Answer 33

- Causes noise - Scarring of the landscape - Loss of habitats - Abandoned deep mine shafts can be dangerous

Question 34

Give 6 reasons to recycle metals.

Answer 34

- Mining and extracting metals uses up energy and therefore fossil fuels which causes more acid rain, global dimming and climate change - Fossil fuels are running out and so need to be conserved - Recycling saves money as energy is expensive - Recycling conserves metal resources in the earth - Recycling cuts down on the amount of rubbish = less landfill

Question 35

How much iron does cast iron contain?

Answer 35

96% - the rest is carbon

Question 36

Why does cast iron have limited uses?

Answer 36

It is brittle

Question 37

What is the one good property of cast iron?

Answer 37

Good strength in compression

Question 38

What is cast iron used for?

Answer 38

Ornamental railings

Question 39

What is high carbon steel used for and why?

Answer 39

- Bridges and cutting tools | - It's very hard, inflexible and brittle

Question 40

What is low carbon steel used for and why?

Answer 40

- Car bodies | - Easily shaped

Question 41

What is stainless steel used for and why?

Answer 41

- Cutlery and containers for corrosive substances | - Its corrosive resistant

Question 42

Why are alloys harder than pure metals?

Answer 42

- Different elements have different sized atoms - When carbon is added to pure iron, the smaller carbon atoms upset the regular arrangement of the pure iron atom layers - This makes it more difficult for them to slide over each other

Question 43

Why are pure metals such as copper, gold and aluminium mixed with small amounts of similar metals?

Answer 43

They would be too soft otherwise, they are mixed to make them harder for everyday use

Question 44

Give 4 examples of alloys used today

Answer 44

- Copper + tin = bronze = hard = medals and statues - Copper + nickel = cupronickel = hard and corrosion resistant = silver coins - Gold alloys = harder = jewellery - Aluminium alloys = strong and low density = aircraft

Question 45

Give 4 properties of transitional metals

Answer 45

- Strong - Can be bent and hammered into shapes - Conductors of heat - Conductors of electricity

Question 46

What are transitional metals useful for?

Answer 46

- Bridges - Something for heat to travel through e.g a saucepan base - Electrical wires

Question 47

What are the two main uses of copper and what properties make it useful for this?

Answer 47

- Electrical wiring = good conductor of electricity | - Plumbing = doesn't react with water, hard and strong but can be bent

Question 48

What is aluminium used for and what properties make it useful for this?

Answer 48

- Strong - Can bent into shape - Light - Airplanes

Question 49

What is titanium used for and what properties make it useful for this?

Answer 49

- Light - Doesn't corrode - Doesn't bend easily - Replacement hips

Question 50

What are the problems with metals as materials?

Answer 50

- Many corrode when exposed to air and water (need painting) | - Metals can get 'tired' when stress and strain is repeatedly on them over time (known as metal fatigue)