extraction and uses of metals

Question 1

What is an ore?

Answer 1

a mineral that contains enough of a metal/compound to make it worthwhile extracting

Question 2

What are the two main methods of extracting?

Answer 2

• electrolysis

- heating with reducing agent

Question 3

Which metals in reactivity series require electrolysis?

Answer 3

all metals above carbon

Question 4

Which metals in reactivity series require heating with a reducing agent?

Answer 4

zinc, iron, copper

Question 5

which reducing agent is usually used?

Answer 5

carbon or carbon monoxide

Question 6

how is silver/gold extracted?

Answer 6

they occur naturally

Question 7

Which method of extraction is aluminium

Answer 7

electrolysis

Question 8

What are the electrodes made out of?

Answer 8

graphite (carbon)

Question 9

What is the electrolyte made out of?

Answer 9

solution of aluminium oxide dissolved in molten cryolite

Question 10

What is the main ore of aluminium?

Answer 10

bauxite

Question 11

Why is it dissolved in molten cryolite?

Answer 11

• bauxite has high melting point
• cryolite lower melting point
• cheaper and also better conductor of electricity than molten aluminium oxide

Question 12

What is formed at cathode?

Answer 12

aluminium

Question 13

What is formed at anode?

Answer 13

oxygen + 4 electrons

Question 14

How is aluminium collected?

Answer 14

• melted
• collects at bottom
• tapped off

Question 15

Why do electrodes need replacing?

Answer 15

• react with graphite to form carbon dioxide
• electrodes burn away
• regularly needs replacing

Question 16

Raw materials needed for extraction of iron

Answer 16

• haematite (iron ore)
• coke (carbon)
• limestone (calcium carbonate
• air

Question 17

Where are the raw materials inserted?

Answer 17

• hot air blasted at bottom

- rest are mixed and fed in at top

Question 18

How is carbon monoxide formed?

Answer 18

• oxygen in air reacts with coke to form carbon dioxide

- carbon dioxide reacts with coke to form carbon monoxide

Question 19

What is the purpose of the carbon monoxide?

Answer 19

• reducing agent for iron

Question 20

What happens once the iron is reduced?

Answer 20

• melts

- collects at bottom of furnace where it is tapped off

Question 21

What happens to the limestone?

Answer 21

calcium carbonate decomposes to form calcium oxide

Question 22

What happens to the calcium oxide?

Answer 22

reacts with silicon dioxide (impurity of iron ore) to form calcium silicate

Question 23

What happens to the silicate?

Answer 23

melts and collects as molten slag on top of molten iron

Question 24

What is molten slag?

Answer 24

waste material produced in blast furnace during the production of iron

Question 25

What is the cooled slag used for?

Answer 25

• road-building

- fertiliser

Question 26

Properties of iron and aluminium

Answer 26

• dense and lustrous
• high melting ponts
• high tensile strength
• malleable
• good conductors of electricity and heat

Question 27

what is wrought iron? give a property and uses

Answer 27

• pure iron
• malleable
• gates/ railings

Question 28

what is cast iron? give a property and uses

Answer 28

• iron with 4% carbon and silicon (pig iron remelted under controlled conditions)
• brittle
• drainpipes, manholes, cooking pans

Question 29

what is steel? give a property and uses

Answer 29

• alloy of iron, carbon and other metals
• hard but malleable(strong)
• car bodies, girders, bridges, ships, nails

Question 30

what is stainless steel? give a property and uses

Answer 30

• alloy of iron and chromium and nickel (strong oxide layers protect iron from rust)
• resistant to corrosion
• cutlery, kitchen utensils, kitchen sinks

Question 31

why is aluminium useful for food cans?

Answer 31

• resists corrosion

- non-toxic

Question 32

why is aluminium useful for window frames?

Answer 32

resists corrosion

Question 33

why is aluminium useful for aeroplane bodies/ bicycle frames?

Answer 33

• less dense than iron: weight of them

Question 34

why is aluminium useful for power cables?

Answer 34

good conductor of electricity

Question 35

why is aluminium useful for saucepans?

Answer 35

good conductor of heat