C6.3 - The extraction of aluminium

Question 1

Aluminium is a very what metal?

Answer 1

Aluminium is a very important metal

Question 2

Examples of the uses of aluminium, or its alloys

Answer 2

Examples of the uses of aluminium, or its alloys are:

1. Pans
2. Overhead power cables
3. Aeroplanes
4. Cooking foil
5. Drink cans
6. Window and patio door frames
7. Bicycle frames and car bodies

Question 3

Why must you use electrolysis to extract aluminium?

Answer 3

You must use electrolysis to extract aluminium, because carbon is not reactive enough to use

Question 4

When aluminium is electrolysed, what is the compound?

Answer 4

When aluminium is electrolysed, the compound is aluminium oxide, Al2O3

Question 5

What ore do you get aluminium oxide from?

Answer 5

You get aluminium oxide from the bauxite ore

Question 6

How is bauxite mined?

Answer 6

Bauxite is mined by open cast mining, digging it directly from the surface

Question 7

You get aluminium oxide from the bauxite ore.

What does bauxite contain?

Answer 7

Bauxite contains mainly aluminium oxide

Question 8

Bauxite contains mainly aluminium oxide, but it is mixed with other rocky impurities, so the 1st step is to separate aluminium oxide from the ore.
What do the other rocky impurities in the bauxite ore contain?

Answer 8

The other rocky impurities in the bauxite ore contain a lot of iron(III) oxide

Question 9

The other rocky impurities in the bauxite ore containing a lot of iron(III) oxide makes the colour of the waste solution from the separation process a what colour?

Answer 9

The other rocky impurities in the bauxite ore containing a lot of iron(III) oxide makes the colour of the waste solution from the separation process a rusty brown colour

Question 10

The rusty brown wastewater from the separation process of aluminium oxide from the bauxite ore have to be stored in what?

Answer 10

The rusty brown wastewater from the separation process of aluminium oxide from the bauxite ore have to be stored in large lagoons

Question 11

What does the electrolysis of aluminium oxide require?

Answer 11

The electrolysis of aluminium oxide requires a lot of energy

Question 12

Once purified, why must happen to the aluminium oxide?

Answer 12

Once purified, the aluminium oxide must be melted

Question 13

Once purified, why must the aluminium oxide be melted?

Answer 13

Once purified, the aluminium oxide must be melted, to enable the ions to move to the electrodes

Question 14

What is the melting point of aluminium oxide?

Answer 14

The melting point of aluminium oxide is very high at 2050 degrees Celsius

Question 15

Chemists save at least some energy when melting aluminium oxide by doing what?

Answer 15

Chemists save at least some energy when melting aluminium oxide by mixing the aluminium oxide with molten cryolite

Question 16

Cryolite

Answer 16

Cryolite is an ionic compound

Question 17

The melting point of aluminium oxide is very high at 2050 degrees Celsius.
However, chemists save at least some energy when melting aluminium oxide by mixing the aluminium oxide with molten cryolite.
The molten mixture of aluminium oxide and cryolite be electrolysed at the temperature of what?

Answer 17

The molten mixture of:
1. Aluminium oxide
2. Cryolite
be electrolysed at the temperature of about 850 degrees Celsius

Question 18

What keeps the mixture of aluminium oxide and cryolite molten?

Answer 18

The large amount of electrical energy that is transferred to the electrolysis cells keeps the mixture of:
1. Aluminium oxide
2. Cryolite
molten

Question 19

In the electrolysis of aluminium oxide, the aluminium oxide is dissolved in molten cryolite, so the ions are what?

Answer 19

In the electrolysis of aluminium oxide, the aluminium oxide is dissolved in molten cryolite, so the ions are free to move (conduct electricity)

Question 20

In the electrolysis of aluminium oxide, the aluminium metal that is formed at the cathode is what?

Answer 20

In the electrolysis of aluminium oxide, the aluminium metal that is formed at the cathode is:

1. Molten at the temperature of the cell
2. Collects at the bottom

Question 21

In the electrolysis of aluminium oxide, after the oxygen atoms covalently bond in pairs to form molecules of oxygen gas (O2), what does the oxygen do?

Answer 21

In the electrolysis of aluminium oxide, after the oxygen atoms covalently bond in pairs to form molecules of oxygen gas (O2), the oxygen reacts with the hot carbon anodes

Question 22

In the electrolysis of aluminium oxide, after the oxygen atoms covalently bond in pairs to form molecules of oxygen gas (O2), the oxygen reacts with the hot carbon anodes, making carbon dioxide gas which goes into our atmosphere.
What happens as a result?

Answer 22

As a result, the carbon anodes:

1. Gradually burn away
2. Need to be replaced regularly

Question 23

What do the electrodes having to be replaced regularly add to?

Answer 23

The electrodes having to be replaced regularly adds the cost process of the electrolysis of aluminium oxide

Question 24

What do aluminium alloys have?

Answer 24

Aluminium alloys have a low density

Question 25

What does the process of extracting aluminium require?

Answer 25

The process of extracting aluminium requires a lot of energy

Question 26

The process of extracting aluminium requires a lot of energy. What does the purification of aluminium oxide from the ore make?

Answer 26

The purification of aluminium oxide from the ore makes aluminium oxide

Question 27

The process of extracting aluminium requires a lot of energy. The purification of aluminium oxide from the ore makes aluminium hydroxide. What happens to this?

Answer 27

This is separated from the impurities

Question 28

The process of extracting aluminium requires a lot of energy. The purification of aluminium oxide from the ore makes aluminium hydroxide. This is separated from the impurities, but then must be heated to turn it back to pure aluminium oxide. Then, what happens?

Answer 28

Then, even more energy is needed to: 1. Melt 2. Electrolyse the oxide

Question 29

What does an aluminium plant use?

Answer 29

An aluminium plant uses the same amount of electricity as a small town

Question 30

You must use electrolysis to extract aluminium, because carbon is not reactive enough to use, because it cannot do what?

Answer 30

You must use electrolysis to extract aluminium, because carbon is not reactive enough to use, because it cannot displace aluminium from its compounds

Question 31

You get aluminium oxide from the bauxite ore. Bauxite contains mainly aluminium oxide. Bauxite contains mainly aluminium oxide, but it is mixed with what?

Answer 31

Bauxite contains mainly aluminium oxide, but it is mixed with other rocky impurities

Question 32

You get aluminium oxide from the bauxite ore. Bauxite contains mainly aluminium oxide. Bauxite contains mainly aluminium oxide, but it is mixed with other rocky impurities, so the 1st step is to do what?

Answer 32

Bauxite contains mainly aluminium oxide, but it is mixed with other rocky impurities, so the 1st step is to separate aluminium oxide from the ore

Question 33

In the electrolysis of aluminium oxide, the aluminium oxide is dissolved in molten cryolite, so the ions are free to move (conduct electricity). Energy is saved by doing this, because it does what?

Answer 33

Energy is saved by doing this, because it lowers its melting point

Question 34

In the electrolysis of aluminium oxide, the aluminium oxide is dissolved in molten cryolite, so the ions are free to move (conduct electricity). Energy is saved by doing this, because it lowers its melting point, so what?

Answer 34

Energy is saved by doing this, because it lowers its melting point, so that the temperature needed to melt so much is less

Question 35

In the electrolysis of aluminium oxide, the aluminium oxide is dissolved in molten cryolite, so the ions are free to move (conduct electricity). Energy is saved by doing this, because it lowers its melting point, so that the temperature needed to melt so much is less. This is cheaper for what?

Answer 35

This is cheaper for the organisations involved

Question 36

In the electrolysis of aluminium oxide, the aluminium metal that is formed at the cathode is molten at the temperature of the cell and collects at the bottom. It is what?

Answer 36

It is: 1. Siphoned Or, 2. Tapped off

Question 37

In the electrolysis of aluminium oxide, after the oxygen atoms covalently bond in pairs to form molecules of oxygen gas (O2), the oxygen reacts with the hot carbon anodes, making what which goes into our atmosphere?

Answer 37

In the electrolysis of aluminium oxide, after the oxygen atoms covalently bond in pairs to form molecules of oxygen gas (O2), the oxygen reacts with the hot carbon anodes, making carbon dioxide gas which goes into our atmosphere

Question 38

Aluminium alloys have a low density, but are what?

Answer 38

Aluminium alloys have a low density, but are very strong

Question 39

The process of extracting aluminium requires a lot of energy. The purification of aluminium oxide from the ore makes aluminium hydroxide. This is separated from the impurities, but then must be what?

Answer 39

This is separated from the impurities, but then must be heated to turn it back to pure aluminium oxide