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Chemistry: 1 > Extraction of Metals > Flashcards

Flashcards in Extraction of Metals Deck (34):
1

How do we have to extract metals that are more reactive than carbon?

Using electrolysis of molten compounds

2

Give an example of a metal that has to be extracted using electrolysis

Aluminium

3

Name a disadvantage of using electrolysis compared to reduction using carbon?

4

Describe how extracting aluminium is an expensive process

A high temperature is needed to melt aluminium oxide so that aluminium can be extracted - requiring a lot of energy

5

Why do we use electrolysis with copper when we can extract it using reduction with carbon?

After extracting the copper through reduction with carbon it is still very impure

- electrolysis is used to purify it

6

Describe how copper is purified using reduction with carbon, and name the process

Smelting

Copper ore is heated in a furnace

7

What is the problem with impure copper?

It can't conduct electricity very well, which is a problem as a lot of copper is used to make electrical wiring

8

Why do we extract copper using reduction with carbon BEFORE we electrolyise it?

It's less expensive than just using electrolysis

9

Define 'electrolysis'

Breaking down a substance using electricity

10

What does electrolysis require?

A liquid to conduct the electricity, known as the electrolyte

11

What 2 things are electrolytes usually made of?

1. Metal salt solutions made from the ore (e.g. copper sulphate

2. Molten metal oxides

12

How can electrolytes conduct electricity?

Because they contain free ions

13

Describe what the negative and positive electrodes do with the electrons

Negative electrode - gives away electrons

Positive electrode - takes away electrons

14

As the ions lose or gain electrons, what happens to them?

They become atoms or molecules and are released

15

Give the 4 steps of how electrolysis is used to get pure copper

1. Electrons are pulled off copper atoms at the positive electrode

2. This causes them to be released into the solution as Cu2+ ions

3. Cu2+ ions near the negative electrode gain electrons and turn back into copper atoms

4. The impurities are dropped at the positive electrode as sludge, whilst the pure copper atoms bond to the negative electrode

16

Describe the negative electrode for the electrolysis of copper

Starts off as a thin piece of pure copper and more pure copper adds to it

17

Describe the positive electrode for the electrolysis of copper

A lump of impure copper which will dissolve

18

Why is the Statue of Liberty green?

Because the copper coating reacts with the oxygen in the air to form copper carbonate

19

More reactive metals react ____ ____ than less reactive ones

More reactive metals react more vigorously than less reactive ones

20

What happens if you put a reactive metal into a soltion of a dissolved metal compound?

The reactive metal will replace the less reactive metal in the compound

21

Why do more reactive metals displace less reactive metals?

The more reactive metal bonds more strongly to the non-metal part of the compound and pushes out the less reactive metal

22

Explain what happens when you add scrap iron to a solution of copper sulfate, and why this is useful

The more reactive iron displaces the copper, so you are left with copper metal and iron sulfate

This is useful because iron is cheap but copper is expensive

23

What happens if a piece of silver is put into a copper sulfate solution?

Why?

Nothing

Because the copper is the more reactive metal, and it is already bonded to the sulfur

24

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

Because the supply of copper-rich ores is limited

25

The demand for copper is ____, and this may lead to ____ in the future

The demand for copper is growing, and this may lead to shortages in the future

26

What is the demand and limited supply of copper causing scientists to do?

Look into new ways of extracting copper from low-grade ores, or from the waste that is currently produced when copper is extracted

27

Name two examples of new methods to extract copper

1. Bioleaching

2. Phytomining

28

Define 'bioleaching'

Using bacteria to separate copper from copper sulfide.

29

Describe the process of bioleaching

The bacteria get energy from the bond between copper and sulfur, serparating out the copper from the ore in the process. The leachate (the solution produced by the process) contains copper, which can be extracted

30

Give an example of how the copper can be separated out from the leachate

Filtration

31

Define 'phytomining'

Growing plants in soil that contains copper, then harvesting them

32

Describe the process of phytomining

(4 steps)

1. Plants are grown in soil that contains copper.

2. The plants can't use or get rid of the copper so it gradually builds up in the leaves.

3. The plants can be harvested, dried, and burned in a furnace.

4. The copper can be collected from the ash left in the furnace.

33

Name an advantage of bioleaching and phytomining to traditional methods of copper extraction

They have a much smaller impact on the environment

34

Name a disadvantage of bioleaching and phytomining to traditional methods of copper extraction

They are much slower