extraction and uses of metals Flashcards

(35 cards)

1
Q

What is an ore?

A

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

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2
Q

What are the two main methods of extracting?

A
  • electrolysis

- heating with reducing agent

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3
Q

Which metals in reactivity series require electrolysis?

A

all metals above carbon

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4
Q

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

A

zinc, iron, copper

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5
Q

which reducing agent is usually used?

A

carbon or carbon monoxide

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6
Q

how is silver/gold extracted?

A

they occur naturally

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7
Q

Which method of extraction is aluminium

A

electrolysis

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8
Q

What are the electrodes made out of?

A

graphite (carbon)

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9
Q

What is the electrolyte made out of?

A

solution of aluminium oxide dissolved in molten cryolite

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10
Q

What is the main ore of aluminium?

A

bauxite

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11
Q

Why is it dissolved in molten cryolite?

A
  • bauxite has high melting point
  • cryolite lower melting point
  • cheaper and also better conductor of electricity than molten aluminium oxide
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12
Q

What is formed at cathode?

A

aluminium

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13
Q

What is formed at anode?

A

oxygen + 4 electrons

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14
Q

How is aluminium collected?

A
  • melted
  • collects at bottom
  • tapped off
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15
Q

Why do electrodes need replacing?

A
  • react with graphite to form carbon dioxide
  • electrodes burn away
  • regularly needs replacing
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16
Q

Raw materials needed for extraction of iron

A
  • haematite (iron ore)
  • coke (carbon)
  • limestone (calcium carbonate
  • air
17
Q

Where are the raw materials inserted?

A
  • hot air blasted at bottom

- rest are mixed and fed in at top

18
Q

How is carbon monoxide formed?

A
  • oxygen in air reacts with coke to form carbon dioxide

- carbon dioxide reacts with coke to form carbon monoxide

19
Q

What is the purpose of the carbon monoxide?

A
  • reducing agent for iron
20
Q

What happens once the iron is reduced?

A
  • melts

- collects at bottom of furnace where it is tapped off

21
Q

What happens to the limestone?

A

calcium carbonate decomposes to form calcium oxide

22
Q

What happens to the calcium oxide?

A

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

23
Q

What happens to the silicate?

A

melts and collects as molten slag on top of molten iron

24
Q

What is molten slag?

A

waste material produced in blast furnace during the production of iron

25
What is the cooled slag used for?
- road-building | - fertiliser
26
Properties of iron and aluminium
- dense and lustrous - high melting ponts - high tensile strength - malleable - good conductors of electricity and heat
27
what is wrought iron? give a property and uses
- pure iron - malleable - gates/ railings
28
what is cast iron? give a property and uses
- iron with 4% carbon and silicon (pig iron remelted under controlled conditions) - brittle - drainpipes, manholes, cooking pans
29
what is steel? give a property and uses
- alloy of iron, carbon and other metals - hard but malleable(strong) - car bodies, girders, bridges, ships, nails
30
what is stainless steel? give a property and uses
- alloy of iron and chromium and nickel (strong oxide layers protect iron from rust) - resistant to corrosion - cutlery, kitchen utensils, kitchen sinks
31
why is aluminium useful for food cans?
- resists corrosion | - non-toxic
32
why is aluminium useful for window frames?
resists corrosion
33
why is aluminium useful for aeroplane bodies/ bicycle frames?
- less dense than iron: weight of them
34
why is aluminium useful for power cables?
good conductor of electricity
35
why is aluminium useful for saucepans?
good conductor of heat