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Chemistry Yr 9 > Extraction And Uses Of Metals > Flashcards

Extraction And Uses Of Metals Flashcards

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1
Q

Infinite or finite number of metal ores?

A

They are know as “finite resources”

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2
Q

How does the reactivity series help us with extracting metals?

A

The more reactive a metal is, harder it is to extract it from a compound

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3
Q

What is the reaction called that separates pure metal from their oxides?

A

The reaction the separates a metal from the oxygen in its oxide is called a reduction reaction

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4
Q

What is reduction? Example

A

Loss of oxygen

E.G. Copper oxide + carbon —> copper + oxygen

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5
Q

What is the substance that is oxidised called in a reduction reaction?

A

The reducing agent as is reduced to its ‘normal’ form

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6
Q

How is a reduction reaction done with carbon?

A

A less reactive metal ore is heated with carbon monoxide

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7
Q

What makes a metal compound a metal ore?

A

If it has enough metal in it that it is pronounced worth extracting

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8
Q

How do you extract aluminium?

A

By using electrolysis

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9
Q

What is the symbol for pure aluminium oxide?

A

Al O

2 3

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10
Q

What is aluminium a main ore?

A

Bauxite

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11
Q

Why don’t we melt bauxite?

A

It has a very high boiling point at over 2000°C as it would be very expensive

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12
Q

What is aluminium oxide dissolved in to bring the boiling point down?

A

Cryolite ( a less common ore of aluminium ) this brings the boiling point down to around 900°C which makes it easier to melt

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13
Q

Why is electrolysis expensive?

A
  • Requires a lot of electricity and energy to heat the mixture = expensive
  • The disappearing positive electrode needs frequent replacement
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14
Q

What is the equation for the decomposition of of aluminium oxide?

A

Aluminium oxide —> aluminium + oxygen

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15
Q

What is the negative electrode known as?

A

Cathode

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16
Q

What is the positive electrode known as?

A

Anode

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17
Q

Why does the molten aluminium conduct electricity?

A

Because it contains free ions which can transport electricity

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18
Q

What happens to the positive aluminium ions?

A

They are attracted to the negative electrode called the cathode where they pick up electrons and turn into aluminium atoms then they sink to the bottom

19
Q

What happens to the negative oxygen ions during electrolysis?

A

They are attracted to the positive electrode called the anode where they lose electrons. The oxygen atoms react together to form O2 or with the carbon anode as well to form to CO2

20
Q

Why does the anode or the positive electrode often need replacing?

A

Because it is constantly reacting with oxygen and so gets worn down

21
Q

What is the symbol equation for what is happening at the cathode?

A

Al 3+ + 3e - —> Al

22
Q

What is the symbol equation for what is happening at the anode?

A

2O 2- —> O + 4e -

2

23
Q

Where is iron extracted from? What is its symbol?

A

Iron is extracted from its ore called haematite
Fe O
2 3

24
Q

How is iron extracted from its ore?

A

By reduction (removal of oxygen) in a blast furnace

25
Q

What are the ingredients that are put into a blast furnace and what do they do?

A

Iron ore - contains iron
Coke (almost pure carbon) - reducing the iron oxide to iron metal
Limestone - takes away impurities in the form of slag

26
Q

What is the first step in extracting iron from and iron ore using a blast furnace?

A

Hot air is blasted into the furnace, making the Coke burn much faster than normal, raising the temperature inside the furnace to about 1500°C

27
Q

What is the second step in extracting iron from and iron ore using a blast furnace? What is the symbol equation?

A

Coke burns and produces carbon dioxide
Carbon + oxygen —> carbon dioxide
C + O —> CO
2 2

28
Q

What is the third step in extracting iron from and iron ore using a blast furnace? What is the symbol equation?

A

The carbon dioxide reacts with the u burnt coke to form carbon monoxide.
Carbon dioxide + carbon —> carbon monoxide
CO + C —> 2CO
2

29
Q

What is the forth step in extracting iron from and iron ore using a blast furnace? What is the symbol equation?

A

The carbon monoxide then reduces the iron ore to iron
Carbon monoxide + iron (III) oxide —> carbon dioxide + iron
3CO + Fe O —> 3CO + 2Fe
2 3 2

30
Q

What is the final step in extracting iron from and iron ore using a blast furnace?

A

The iron is molten at this temperature and also is very dense. As such it falls straight to the bottom of the furnace and is tapped off there

31
Q

What is the main impurity and what removes it?

A

Sand (silicon dioxide) is the main impurity and it is removed by limestone

32
Q

How does the limestone remove the sand?

A

The limestone is decomposed by the heat into calcium oxide and CO(2)
CaCO —> CaO + CO
3 2
The calcium oxide reacts with the sand to form calcium silicate or slag which is molten can be tapped off
CaO + SiO —> CaSiO
2 3

33
Q

What can the slag be used for?

A

The cooled slag is solid and can be used for roadbuilding or for fertiliser

34
Q

What properties do iron and aluminium share?

A
  • Both metals
  • Both dense and shiny
  • Both have high melting points
  • Both have high tensile strength (strong and hard to break)
  • Both malleable (hammered into shape)
  • Both good conductors of heat energy and electricity
35
Q

What is wrought iron, and what is it used for?

A

It is completely pure iron that is malleable and often used for ornamental gates and railings

36
Q

What are two examples of iron alloys?

A

Cast iron

Steel

37
Q

What is cast iron and what is it used for?

A

It is iron with a mixture of carbon and silicon. It is very hard but brittle.
It is often used for manhole covers and some cooking pans

38
Q

What is steel and what is it used for?

A

Steel is an alloy made up of iron, carbon and usually some other metals.
It is harder than pure iron but can be hammered and made easily into sheets and welded together.
These properties mean steel is great making carbodies and girders (for construction)

39
Q

Why is cutlery made out of stainless steel?

A

Because pure iron rusts very easily. Stainless steel is an alloy made from iron and chromium and it does not rust.

40
Q

What is the main way that aluminium different from iron?

A

Aluminium does not corrode easily

41
Q

Why is it useful that aluminium does not corrode?

A

Because it means that it can be used for products where liquid is involved and will not rust such as with fizzy drink cans

42
Q

Why is aluminium particularly useful for aeroplanes and bicycle frames?

A

Because aluminium is a lot less dense than iron meaning that it is quite light. It is used for aeroplanes because of this

43
Q

Talk about aluminium and aluminium oxide. How is it useful?

A

Aluminium react very quickly with oxygen in the air to form aluminium oxide.
A nice protective layer of aluminium oxide sticks firmly to the aluminium below and stops any further reaction taking place.

Chemistry Yr 9 (7 decks)

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