❌C6.1 (3) - extractions Flashcards

c6.1.6 - extracting metals c6.1.7 - extracting iron c6.1.8 - extracting aluminium c6.1.9 - biological metal extraction

1
Q

define an ore

A

a mineral or rock that contains a enough metal/metal compound to make it economical to extract the metal

(= the value of the metal is more than the cost of extracting it)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what is the ore to extract copper (carbonate)?

A

malechite

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what is the ore to extract iron(III) (oxide)?

A

haematite

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what is the ore to extract aluminium (oxide)?

A

bauxite

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

describe the 3 main stages to extract a metal

A

1) ore is mined

2) ore is processed
(metal compound separated from other substances in the ore)

3) metal is extracted from the pure method compound using chemical reactions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what is the mneunomic to remember the metal reactivity series?
(and what does each stand for - in terms of elements)

A
pink - potassium
smiling - sodium
cats - calcium
meow - magnesium
at - aluminium
cute - carbon (NOT METAL)
zebras - zinc
in - iron
the - tin
long - lead
hot - hydrogen (NOT METAL, USED FOR REFERENCE) 
curly - copper
swirly - silver
grass - gold
privately - platinium

Please stop calling me a (cute) zebra, I think love has copper silver gold platinum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What extraction methods are there - when are they used

A
  • in principle, all metals could be extracted from their compounds using electrolysis, but electricity is expensive
  • if metal is less reactive than carbon, cheaper methods are used instead
  • copper + iron are less reactive than carbon, so they can be extracted by heating their compounds with carbon or with carbon monoxide
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

all metals can be extracted from their compounds using …… but is expensive

A

electrolysis (electricity is expensive)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

why can copper be extracted using carbon, but not sodium?

A

as copper is less reactive than carbon

- wheras sodium is too reactive to be extracted by reduction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

describe the 2 main steps of how copper is extracted from copper sulfide
(and the word and symbol equation for each one)

A

1) copper sulfide (II) is ‘roasted’ in air
(to get it into metal oxide form for carbon to reduce later) :

copper(II) sulfide + oxygen -> copper(II) oxide + sulfur dioxide
2CuS(s) + 3O2 (g) -> 2CuO(s) + 2SO2 (g)

2) copper(II) oxide is heated with carbon:

copper (II) oxide + carbon -> copper + carbon dioxide
2CuO(s) + C(s) -> 2Cu(s) + CO (g)
2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

explain how the extraction of copper sulfide is a redox reaction
- and what is the reducing agent

A
  • copper(II) oxide loses oxygen and is reduced
  • carbon gains oxygen and is oxidised
  • carbon is acting as a reducing agent (reduced copper oxide to copper)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what form of carbon is used when extracting copper from copper sulfide?

A

charcoal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what is the machinery used to extract iron from its ore called?

A

a blast furnace

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what are the raw materials used to extract iron?

and what is each one’s function

A
  • iron ore (haematite - contains iron needed for extraction)
  • coke (reduces iron(III) oxide to iron)
  • limestone (purifies iron)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

describe the three steps in which iron is extracted

- and the symbol equation for each one

A

1) coke burns in hot air, making carbon dioxide
C(s) + O (g) -> CO (g)
2 2

2) more coke reduces carbon dioxide to carbon monoxide
C(s) + CO (g) -> 2CO(g)
2

3) carbon monoxide reduces iron(III) oxide to iron
3CO(g) + Fe2O3(s) -> 3CO2 (g) + 2Fe (l)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what is the main reducing agent in the blast furnace for extracting iron from iron(III) oxide?
(and why can it do so)

A

carbon monoxide

- it is more reactive than iron

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

in what state does iron leave the blast furnace?

A

molten state (temperatures are very high, 1500C)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

how is extracted iron purified?

A
  • using limestone
    1) calcium carbonate decomposes in the high temperatures :

CaCO3(s) -> CaO(s) + CO2(g)

2) calcium oxide reacts with silica from the sandy impurities from extracted iron to form calcium silicate:

CaO(s) + SiO2(g) -> CaSiO3(l)

The molten calcium silicate is called slag. It floats on the molten iron, and both the iron and slag are removed separately at the bottom of the blast furnace.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

how does purified iron leave the blast furnace?

A
  • as molten calcium silicate/slag floats on the molten iron (as it is less dense)
  • iron leaves from bottom tube in liquid state
  • slag leaves from tube on top of it
20
Q

what does impure iron contain?

A

sandy impurities

21
Q

why is the reaction between calcium oxide and silica a neutralization reaction?

A

as calcium oxide is slightly alkalinic

and silica is slightly acidic

22
Q

how does a blast furnace work?

A
  • raw materials added to top of blast furnace
    (iron ore, such as haematite, which contains iron(III) oxide;
    coke;
    limestone, which is used to purify the iron )
  • hot air forced in at the bottom of furnace = high temperature
  • they react together at a high temperature
23
Q

what is coke?

A
  • a compound made of mostly carbon

- formed by heating coal in the absence of air

24
Q

why is electrolysis used to extract some metals from their ores?
(and give an example)

A

if they are more reactive than carbon

ie. aluminum

25
Q

why is aluminium oxide dissolved in molten cryolite?

A
  • as electrolysis only works if the compound is in solution or molten (so ions can move)
  • melting point of aluminium oxide is very high
  • and aluminum oxide does not dissolve in water
  • cryolite lowers melting point of aluminium oxide from 2000C to 950C
26
Q

what is the structure which allows aluminium to be extracted from aluminium oxide?

(and what is it made of)

A

huge electrolysis cell

  • carbon anodes
  • carbon lining of cell (cathode)
  • insulation on outside of cell
27
Q

what is produced at the cathode and anode during electrolysis/extraction of aluminium?

(is it oxidation/reduction)

A

cathode (-) = aluminium ions are reduced (gain electrons)

anode (+) = oxygen ions are oxidised (lose electrons)

28
Q

2 reasons why extraction of aluminium is expensive

A
  • requires electricity (for electrolysis)

- carbon anodes constantly need replacing as oxygen reacts with carbon to produce carbon dioxide

29
Q

how is aluminium oxide seperated?

A
  • as in molten state, Al3+ ions and O2- ions are free to move around
  • so aluminium is reduced by the carbon lining of cell and becomes molten aluminium
  • as it is more dense than the aluminium oxide cryolite solution, it sinks
  • and leaves the cell through the tapping hole (molten)
  • oxygen ions are oxidised by the suspended carbon anodes
  • and later react with the carbon and produce carbon dioxide
30
Q

downside of extracting aluminium?

A

released carbon dioxide which is a greenhouse gas

31
Q

write the half equations that happen at each electrode when aluminium oxide is extracted

A

cathode:
Al3+ + 3e- -> Al

anode:
2O 2- -> O2. + 4e-

32
Q

what material lines the cathode and anode in the extraction of aluminium?

A

graphite

33
Q

name 2 examples of alternative biological methods of metal extraction (and describe each one briefly)

A

bioleaching

  • when bacteria breaks down low grade ores to metal compounds
  • and produce leachate solutions with dissolved metal compounds

phytoextraction

  • when plants absorb metal compounds from low-grade soil
  • trapped within leaves/stem
  • then burned to extract metals
34
Q

how are the metals in bioleaching extracted?

A

metals are dissolved in solution, and dissolve in a stream/river
(collected at end)

35
Q

why do bacteria cause the process of bioleaching to occur?

A
  • similar to how we get energy from respiration

- bacteria get energy from breaking bonds

36
Q

positives of bioleaching?

A
  • energy efficient (compared to electrolysis)
  • cheaper than traditional mining and processing
  • no toxic greenhouse gases released
37
Q

negatives of bioleaching?

A
  • very slow

- toxic substances usually produced (must take care )

38
Q

what allows metals to be extracted through phytoextraction?

A
  • plant is burned
  • ash contains a high concentration of metals
  • which are extracted
39
Q

what does a complexing agent do?

A

allows plants to absorb ions more easily (during phytoextraction)

40
Q

positives of phytoextraction?

A
  • cheaper than mining or processing
  • less energy needed
  • close to carbon neutral (carbon dioxide released when burning is absorbed when growing)
  • allows a high concentration of metals to be extracted
41
Q

negatives of phytoextraction?

A
  • very slow
  • reliant on the weather
  • only certain plants absorb certain metal compounds
42
Q

what is good about phytoextraction and bioleaching?

A

both can extract metals from low-grade ores (which would have been unviable)

  • and some ores are becoming scarce
43
Q

What does the method chosen to extract a metal depend upon

A

Its position in the reactivity series

44
Q

Extracting metals topic:

Copper(II) oxide can also be reduced to copper by heating it with __ or with __
Rather than carbon

A

Methane, hydrogen

45
Q

Extracting iron topic:

Iron is extracted from a large reaction container called what?

A

Blast furnace

46
Q

Why is limestone added to blast furnace - in a sentence

A

Limestone - used to purity the iron