Other Methods Of Extracting Metals

Question 1

how are metals that are more reactive than carbon extracted

Answer 1

by using electrolysis of molten compounds

Question 2

what is done once the metal ore is melted to produce a molten compound

Answer 2

• an electric current is passed through it
• the metal is discharged at the cathode
• and the non-metal at the anode

Question 3

what is done to extract aluminium from its ore

Answer 3

• electrolysis is used using carbon electrodes
• aluminium oxide (the form it is in in the ore) has a high melting point
• so the ore is dissolved in molten cryolite to lower the metling point

Question 4

what is molten cyrolite

Answer 4

an aluminium compound with a lower melting point than aluminium oxide

Question 5

what are the ions in the molten mixture of aluminium oxide able to do

Answer 5

the ions are free to move

Question 6

what is formed at each electrode during the electrolysis of aluminium oxide

Answer 6

• aluminium ions are attracted to the cathode
• where they are discharged and aluminium forms
• while oxygen ions are attracted to the anode
• where they are discharged and oxygen gas forms
• 2Al2O = 4Al + 3O

Question 7

;what do you need in order to run electrolysis to extract metals from their ores and why does this make it expensive

Answer 7

• you need large amounts of electricity

- electricity is expensive, so electrolysis is a pricey process

Question 8

what other than the electricity required for electrolysis makes it expensive

Answer 8

• the cost associated with melting or dissolving the metal ore
• so that it can conduct electricity

Question 9

what is the extraction of metals using reduction with carbon compared to electrolysis and why

Answer 9

• it is much cheaper
• because carbon is cheap
• and also acts as the fuel to provide the heat needed for the reduction reaction to happen

Question 10

if reduction using carbon is cheaper than electrolysis, but you need electrolysis in order to extract metals that are more reactive than carbon, what conclusion can you draw from the the costs of metal extraction regarding the metals in the reactivity series

Answer 10

• metals lower down the reactivity series (lower than carbon) are cheaper to extract
• than metals higher up the reactivity series (higher than carbon) which are more expensive

Question 11

what supply is currently limited

Answer 11

the supply of metal rich ores

Question 12

why may we have a shortage of metal rich ores in the future

Answer 12

• because the supply of them is limited

- but the demand for the metals they contain is growing

Question 13

what are scientists currently trying to do in response to the shortage but high demand for metal rich ores

Answer 13

• they are looking into ways of extracting metals from low grade ores
• or from the waste that is currently produced when metals are extracted

Question 14

what is a low grade ore

Answer 14

ores that only contain small amounts of the metal

Question 15

what are the two new methods of extraction that are currently in use

Answer 15

• bioleaching

- phytoextraction

Question 16

why is bioleaching and phytoextraction considered to be biological methods of extraction

Answer 16

because they use living organisms

Question 17

how does bioleaching work

Answer 17

• it uses bacteria to separate metals from their ores
• the bacteria get energy from the bonds between the atoms in the ore
• separating out the metal from the ore in the process
• the leachate contains metal ions which can be extracted by electrolysis or displacement

Question 18

what is an example of bacteria being used to separate metals from their ores and what is the leachate

Answer 18

• copper can be separated from copper sulfide in this way

- the leachate is the solution produced from the bioleaching process

Question 19

how does phytoextraction work

Answer 19

• it involves growing plants in soil that contain metal compounds
• the plants cant use or get rid of the metals so they gradually build up in the leaves
• the plants can be harvested, dried and burned in a furnace
• the ash contains metal compounds from which the metal can be extracted by electrolysis or displacement reactions

Question 20

what is an advantage and disadvantage of the new methods of metal extraction

Answer 20

• they are safer to the environment than other methods such as mining so they have a smaller impact
• but they are quite slow compared to other methods