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Chemistry > Extraction And Uses Of Metals Maud > Flashcards

Extraction And Uses Of Metals Maud Flashcards

1
Q

When is the method of heating the ore with carbon or carbon monoxide used?

A

When a metal is less reactive than zinc

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2
Q

What is electrolysis used for

A

Extracting metals that are more reactive than zinc

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3
Q

The name of aluminium’s ore?

A

Bauxite

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4
Q

What is bauxite

A

Impure aluminium oxide

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5
Q

Equation for aluminium ions being reduced to aluminium?

A

Al 3+ + 3e- –> Al

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6
Q

Equation for oxygen ions forming oxygen gas?

A

2O 2- –> O2 + 4 e-

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7
Q

How does bauxite become aluminium and oxygen?

A

The aluminium ions are attracted to the cathode and are reduced to aluminium

Oxygen ions are attracted to the anode and lose electrons to form oxygen gas

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8
Q

What is aluminium oxide dissolved in and why?

A

It is dissolved in an aluminium compound called cryolite as a flux to lower its melting point

Melting aluminium oxide requires extremely high temperatures

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9
Q

Why do the anodes have to be replaced regularly?

A

Because of the high temperatures, the carbon anodes will burn with the oxygen produced to form carbon dioxide.

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10
Q

What currents do the cells have?

What does this mean?

A

Currents up to 100 000

This means it is expensive

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11
Q

Why is aluminium good for making aircraft with?

A

Resists corrosion due to its aluminium oxide coat

Has low density

Strong

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12
Q

Why is aluminium good for making saucepans with?

A

Keeps its shiny appearance

Good conductor of heat

Resists corrosion

Low density

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13
Q

Why does aluminium resist corrosion?

A

Because of its tenacious oxide layer

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14
Q

What method is used to extract aluminium?

A

Electrolysis

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15
Q

What method is used to extract iron?

A

The blast furnace

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16
Q

What is the name of irons ore?

A

Haematite

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17
Q

What is haematite?

A

An ore that contains iron (III) oxide

18
Q

What is coke and what is it used for?

A

Coke is impure carbon that burns to form carbon dioxide

It is used to heat the blast furnace as burning it is a strongly exothermic reaction.

19
Q

Blast furnace

Carbon to CO2?

A

C + O2 –> CO2

20
Q

At high temperatures, what happens to the carbon dioxide formed by coke?
Equation?

A

The carbon dioxide is reduced by more carbon to give carbon monoxide

C + CO2 –> 2CO

21
Q

What does carbon monoxide do in the blast furnace?

Equation?

A

It is the main reducing agent

Fe2O3 + 3CO –> 2Fe + 3CO2

22
Q

What is the other reducing agent other than carbon monoxide?

Reaction?

A

Carbon

Fe2O3 + 3C –> 2Fe + 3CO

23
Q

What happens to the limestone in the furnace?

Equation?

A

The heat of the furnace causes the limestone to thermally decompose form calcium oxide and carbon dioxide

CaCO3 –> CaO + CO2

24
Q

What happens to the calcium oxide in the blast furnace?

A

The calcium oxide reacts with acidic silicon dioxide(sand). SiO2 is one of the impurities found in haematite.

Molten calcium silicate is formed and trickles to the bottom of the furnace as molten slag

SiO2 + CaO –> CaSiO3(slag)

25
Q

What goes in at the top of the blast furnace?

A

Iron ore, coke and limestone

26
Q

What comes out at the top of the blast furnace?

A

Hot waste gases

27
Q

What is the blast furnace made from?

A

Steel lines with heat resistant brick

28
Q

What are electrolysis tanks made from?

A

Steel lined with refractory brick

29
Q

What is the temperature range in the blast furnace?

A

400-1800 degrees

30
Q

What goes in at the bottom of the blast furnace?

A

Hot air is blasted in

31
Q

What comes out at the bottom of the blast furnace?

A

Molten slag and below that molten (iron)

32
Q

Types of iron?

A 
Wrought iron
Mild steel
High-carbon steel
Cast iron
Stainless steel
33
Q

Wrought iron (what mixed with, properties and uses?)

A

Pure iron

Very soft

Decorative work such as gates and railings

34
Q

Mild steel (what mixed with, properties and uses?)

A

0.25% carbon

Tough, malleable

Nails, car bodies and ship building

35
Q

High-carbon steel (what mixed with, properties and uses?)

A

0.25 - 1.5% carbon

Hard

Cutting tools

36
Q

Cast iron (what mixed with, properties and uses?)

A

About 4% carbon

Very brittle but strong

Manhole covers
Guttering
Engine blocks

37
Q

Stainless steel (what mixed with, properties and uses?)

A

Chromium and nickel

Resists rusting
Expensive

Cutlery
Cooking utensils

38
Q

Ways of preventing the rusting of iron?

A

Using barriers
Alloying the iron
Using sacrificial anodes

39
Q

Using barriers to prevent the rusting of iron?

A

Keep water / oxygen away from the iron by painting / coating it with oil e.t.c

40
Q

Alloying the iron to prevent it rusting?

A

Such as allowing it with chromium and nickel to produce stainless steel

41
Q

Using sacrificial anodes to prevent iron rusting?

A

Galvanising iron by coating it with a layer of zinc

Zinc is more reactive than Iron and will corrode instead

During the process it loses electrons to form ions

These electrons flow into the iron so any iron atom which has lost electrons immediately regains them

These mean that even if the zinc is scratched, the iron won’t rust

Chemistry (18 decks)

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