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GCSE - Chemistry (New) > Section 5 - Pgs 66-69 > Flashcards

Section 5 - Pgs 66-69 Flashcards

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1
Q

Why are most metals found in ores?

A

They are reactive so they easily form compounds - they are the ores.

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2
Q

What is a metal ore?

A

A compound found in the Earth’s crust from which a metal can be extracted.

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3
Q

What determines how easily a metal is extracted from its ore?

A

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

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4
Q

What is a common compound type for metal ores?

A

Oxides

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5
Q

What is the extraction of a metal from its oxide ore called?

A

Reduction

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6
Q

What is the name for the chemical used to extract a metal from its oxide ore?

A

The reducing agent

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7
Q

What determines the way in which a metal is extracted from its ore?

A
  • If it is less reactive than carbon, it is heated with carbon to remove the oxygen
  • If it is more reactive than carbon, electrolysis is used
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8
Q

Why must aluminium be extracted using electrolysis?

A

It is more reactive than carbon, so the carbon will not ‘steal’ the oxygen from the aluminium.

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9
Q

What is the formula for aluminium ore?

A

Al2O3

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10
Q

What is aluminium ore called?

A

Bauxite (Aluminium oxide)

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11
Q

What is the melting point of aluminium oxide?

A

Over 2000*C

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12
Q

What is cryolite used for in aluminium extraction and why?

A

It is used to dissolve the aluminium oxide in. This is because it has a lower melting point (about 900*C) so it saves energy.

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13
Q

What is cryolite?

A

Another more rare aluminium ore, which has a lower melting point than aluminium oxide.

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14
Q

By what process is aluminium extracted?

A

Electrolysis

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15
Q

What are the electrodes in electrolysis made from?

A

Graphite

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16
Q

What happens at the anode during the extraction of aluminium from aluminium oxide by electrolysis?

A
  • O2- ions lose electrons to become O2 molecules

- These then react with the graphite anode to become CO2

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17
Q

What happens at the cathode during the extraction of aluminium from aluminium oxide by electrolysis?

A
  • Al3+ ions gain electrons to become Al atoms

- These then sink to the bottom

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18
Q

Why does the anode need to be replaced frequently during the electrolysis of aluiminium oxide?

A

The oxygen formed there reacts with the carbon to form CO2, which is wears down the anode.

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19
Q

What type of reaction is the electrolysis of aluminium oxide?

A

Redox

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20
Q

What is the half-equation for the anode during the electrolysis of aluminium oxide?

A

2O2- -> O2 + 4e-

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21
Q

What is the half-equation for the cathode during the electrolysis of aluminium oxide?

A

Al3+ + 3e- -> Al

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22
Q

At which electrodes do oxidation and reduction happen during the electrolysis of aluminium oxide?

A

Oxidation: Anode
Reduction: Cathode

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23
Q

Give the word eqauation for the decomposition of aluminium oxide by electrolysis.

A

Aluminium oxide -> Aluminium + Oxygen

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24
Q

Why is electrolysis so expensive?

A
  • It requires electricity
  • Lots of heat needed to melt cryolite (900*C)
  • Replacing anode
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25
Q

What is the melting point of cryolite?

A

900*C

26
Q

How is iron extracted?

A

Reduction using carbon in a blast furnace.

27
Q

What is iron ore called?

A

Haematite (Iron oxide)

28
Q

What is the formula for iron ore?

A

Fe2O3

29
Q

What are the raw materials used in a blast furnace?

A
  • Iron ore
  • Coke
  • Limestone
    (- Hot air)
30
Q

What is coke?

A

Almost pure carbon

31
Q

What is the chemical name for limestone?

A

Calcium carbonate

32
Q

What is the forumla for limestone?

A

CaCO3

33
Q

Remember to look at all the reactions in the blast furnace.

A

Pg 68 of revision guide

34
Q

What are the products of the blast furnace?

A
  • Molten iron
  • Slag
  • Waste gases
35
Q

Give the reactions in the blast furnace.

A 
Reducing the iron ore to iron:
• C + O2 -> CO2
• CO2 + C -> 2CO
• 3CO + Fe2O3 -> 3CO2 +2Fe
Removing the impurities:
• CaCO3 -> CaO + CO2
• CaO + SiO2 -> CaSiO3
36
Q

What is the temperature in the blast furnace?

A

About 1500*C

37
Q

Give the reactions in the blast furnace used to reduce the iron ore.

A
  • C + O2 -> CO2
  • CO2 + C -> 2CO
  • 3CO + Fe2O3 -> 3CO2 +2Fe
38
Q

Give the reactions in the blast furnace used to remove impurities.

A
  • CaCO3 -> CaO + CO2

* CaO + SiO2 -> CaSiO3

39
Q

Where are slag and iron collected from the blast furnace?

A

At the bottom, because they are very dense and sink to the bottom.

40
Q

What is the formula for slag?

A

CaSiO3

41
Q

What does limestone decompose into in the blast furnace?

A

Calcium oxide and carbon dioxide

42
Q

What is the main impurity which needs to be removed in the blast furnace?

A

Sand

43
Q

What is the chemical name and formula for sand?

A

Silicon dioxide (SiO2)

44
Q

What are some uses of slag?

A
  • Road-building

* Fertiliser

45
Q

What are some common properties of iron and aluminium?

A
  • Dense
  • Lustrous
  • High melting points
  • Strong
  • Malleable
  • Good conductors of electricity and heat
46
Q

What is the melting point of iron?

A

1538*C

47
Q

What is the melting point of aluminium?

A

660*C

48
Q

What are the different forms of iron?

A
  • Wrought iron
  • Cast iron
  • Steel
  • Stainless steel
49
Q

What is wrought iron and what are its properties and uses?

A

Almost pure iron -> Malleable

• Ornamental gates and railings

50
Q

What is cast iron and what are its properties and uses?

A

Mixture of iron, carbon and silicon -> Hard but brittle
• Manhole cover
• Some cooking pans

51
Q

What is steel and what are its properties and uses?

A

Mixture of iron, carbon and some other metals -> Hard but malleable
• Car bodies
• Girders

52
Q

What is stainless steel and what are its properties and uses?

A

Mixture of iron and chromium -> Doesn’t rust
• Knives and forks
• Cooking pans

53
Q

What is the main problem with iron and how is this solved?

A

It rusts easily, which is solved by making stainless steel.

54
Q

What is wrought iron made from and what are its properties?

A

Almost pure iron -> Malleable

55
Q

What is cast iron made from and what are its properties?

A

Mixture of iron, carbon and silicon -> Hard but brittle

56
Q

What is steel made from and what are its properties?

A

Mixture of iron, carbon and some other metals -> Hard but malleable

57
Q

What is stainless steel made from and what are its properties?

A

Mixture of iron and chromium -> Doesn’t rust

58
Q

What are the main differences between the properties of iron and aluminium?

A
  • Aluminium does not corrode as easily as iron.

* Aluminium is lighter than iron.

59
Q

How do aluminium’s properties determine its uses?

A
  • Aluminium is light -> Bicycle frames + aeroplanes

* Aluminium doesn’t corrode easily -> Drinks cans

60
Q

Why doesn’t aluminium corrode easily?

A

The aluminium reacts very quickly with the oxygen in the air to form a protective layer of aluminium oxide, which prevents any further corrosion.

GCSE - Chemistry (New) (18 decks)

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