Extracting Metals

Question 1

What is an ore?

Answer 1

A metal ore is a rock which contains enough metal to make it worthwhile extracting the metal from it

Question 2

What is the ore in many cases?

Answer 2

The oxide of the metal

Question 3

How do most ores need to be extracted?

Answer 3

Using chemical reactions

Question 4

How can economics affect metal extraction?

Answer 4

If the market price of a metal drops a lot it might not be worth extracting it

As technology improves it becomes possible to extract more metal making it worth it

Question 5

What two ways can a metal be extracted from its ore chemically?

Answer 5

Reduction

Electrolysis

Question 6

If an ore is concentrated, what does that mean?

Answer 6

The unwanted Rocky material is removed

Question 7

What else can electrolysis to used to do?

Answer 7

Purify the extracted metal

Question 8

What does reduction mean?

Answer 8

Using carbon- The removal of oxygen

Often requires electrolysis after to purify the metal

Question 9

What determines whether a metal can be extracted by reduction?

Answer 9

It’s position in the reactivity series

Question 10

Which metals can / can’t be extracted by reduction?

Answer 10

Metals below carbon can
Metals above carbon can’t

This is because carbon can only take the oxygen away from metals which are less reactive than itself

Question 11

How are metals more reactive than carbon extracted?

Answer 11

Extracted using Electrolysis of molten compounds

Question 12

Why is electrolysis much more expensive than reduction?

Answer 12

It used a lot more energy due to the high temperature used to melt the oxide so it can be extracted

Question 13

How is copper extracted?

Answer 13

Copper can be extracted by reduction with carbon
The ore is then heated in a furnace (smelting)
The copper produced is impure and doesn’t conduct electricity very well
Electrolysis is used to purify it

Question 14

Define electrolysis?

Answer 14

The breaking down of a substance using electricity

Question 15

What is the liquid required to conduct the electricity in electrolysis known as?

Answer 15

The electrolyte

Question 16

What are the electrolytes often?

Answer 16

Metal salt solutions made from the ore

Or molten metal oxides

Question 17

What does the electrolyte have allowing the process to work?

Answer 17

Free ions

Question 18

Where are electrons taken from / given too?

Answer 18

Taken away by the positive anode and given away by the negative cathode, as ions gain or lose electrons they become atoms or molecules and are released

Question 19

Describe how electrolysis is used to get copper?

Answer 19

1) electrons are pulled off copper the atoms at the anode cashing them to go into solution as Cu2+ ions
2) Cu2+ ions near the cathode gain electrons and turn back into copper atoms
3) the impurities are dropped at the anode as a sludge whilst pure copper atoms bond at the cathode

Question 20

Why do more reactive metals react more vigorously than less reactive metals?

Answer 20

If you put a reactive metal into a solution of a dissolved metal compound the reactive metal will replace the less reactive metal in the compound (displacement)

Question 21

Why does displacement happen?

Answer 21

The more reactive metal bonds more strongly to the non metal part of the compound (pushes out the less reactive metal)

Question 22

Why is it useful that scrap iron can be used to displace copper and what’s the equation for this?

Answer 22

Iron is much cheaper than copper

Copper sulfate + iron —> Iron sulfate + copper

Question 23

Why Is it important to recycle as much copper as possible?

Answer 23

The supply of copper rich ores is limited and the demand for copper is growing which may lead to shortages in the future

Question 24

What are two ways of extracting copper from low grade ores or from the waste of copper extraction?

Answer 24

Bioleaching

Phytomining

Question 25

What is bioleaching?

Answer 25

This uses bacteria to separate copper from copper sulfide
The bacteria get energy from the bond between copper and sulfur separating out the copper from the ore in the process
The leachate (solution produced) contains copper which can be extracted by filtering

Question 26

What is phytomining?

Answer 26

This involved growing plants in soil that contain copper
The plants absorb copper and can’t use or get rid of the copper so it gradually builds up in the leaves
The plants are then harvested , dried and burned in a furnace
The copper can be collected from the ash left in the furnace
Copper extracted from solution made by ash using electrolysis
Pure copper is produced

Question 27

What is a positive and negative of extraction by bioleaching and phytomining?

Answer 27

Positive- they have a much smaller impact on the environment than traditional methods
Extracts from low grade ores
Doesn’t damage landscape
Negative- these processes are much slower
Produces smaller amount of copper
Produces carbon dioxide when plants burn

Question 28

Why is mining metal ores good?

Answer 28

Useful products are made

Provided locals with jobs and boosts economy so services such as health can be improved

Question 29

Why is mining ores bad?

Answer 29

It’s bad for the environment
Causes noise and visual pollution
Loss of habitats
Deep mine shafts can be dangerous for a long time after the mine has been abandoned

Question 30

Why is recycling metals important?

Answer 30

Mining and extracting metals takes a lot of energy which comes from burning fossil fuels which are running out and contribute to acid rain, global dimming and climate change

Question 31

How much energy does recycling use?

Answer 31

Only a small fraction of the energy needed to extract new metals
(Copper = 15% energy of extracting new)

Energy is expensive so recycling saves money

Question 32

What two other reasons is recycling metals important?

Answer 32

There’s a finite amount of metals on earth recycling conserves this

recycling metal cuts down rubbish going into landfill which takes up space and pollutes surroundings

Question 33

Describe mining and smelting?

Answer 33

Copper mined from earth
Copper ore heated in furnace with carbon (smelting and reduction)
Produces impure copper

Copper purified by electrolysis
Pure copper produced

Question 34

What is an advantage and disadvantage of mining, smelting and reduction?

Answer 34

Advantage = quickest and extracts more copper so more economic

Disadvantage= supply
Of copper rich ores is limited 
Noise
Destruction of habitats 
Smelting uses non renewable fuel and produces carbon dioxide adding to global warming