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Chemisty > Extraction of Metals > Flashcards

Extraction of Metals Flashcards

1
Q

how do you extract aluminium?

A

electrolysis

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2
Q

how do you extract iron or copper?

A

reduction

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3
Q

what is O.I.L.R.I.G.?

A

Oxidation

Is

Loss

Reduction

Is

Gain

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4
Q

oxidation can be…

A
  1. loss of electrons
  2. addition of oxygen
  3. loss of hydrogen
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5
Q

reduction can be…

A
  1. gain of electrons
  2. loss of oxygen
  3. gain of hydrogen
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6
Q

why is the extraction of iron a reduction reaction? what is the reducing agent?

A

Fe2O3 + 3CO —> 2Fe + 3CO2

Fe2O3 has lost oxygen

CO is the reducing agent

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7
Q

… reative atoms … … reactive atoms

A

more reative atoms displace less reactive atoms

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8
Q

what is a metal ore?

A

a mineral or mixture of minerals from which it is ‘economically viable’ to extract some metal

ore = rock containing metal

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9
Q

what is economically viable?

A

enough metal in ore to sell a metal or more than it cost to extract

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10
Q

what is rust?

A

hydrated iron oxide

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11
Q

what to most ores contain?

A

metal oxides

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12
Q

what do you need to do to extract a metal from a metal oxide?

A

reduce the oxygen (reduction reaction)

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13
Q

what two factors must you consider when deciding on the method of extraction?

A

cost of energy

cost of reducing agent

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14
Q

what is REDOX

A

it is both reduction and oxidation

they occur together in REDOX

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15
Q

what is a reducing agent?

A

a substance that reduced something else (removes oxygen from another substance)

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16
Q

what is an oxidising agent?

A

a substance that oxidises something else (gives oxygen to another substance)

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17
Q

what is the order of the reactivity series from most reactive to least reactive?

A

potassium

sodium

calcium

magnesium

aluminium

carbon

zinc

iron

tin

lead

hydrogen

copper

silver

gold

platinum

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18
Q

how do you remember the order of the reactivity series from most reactive to least reactive?

A

polly

smith

cut

my

amazingly

cool

zebra

into

two

lamp

hamburger

chops

creating

super

gravy

platas

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19
Q

what are the raw materials in the blast furnace?

A

coke (carbon)

haematite (ore iron oxide)

limestone (mainly calcium carbonate)

air (oxygen)

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20
Q

what are the reactions in the blast furnace?

A

carbon + oxygen —> carbon dioxide

carbon dioxide + carbon —> carbo monoxide

carbon monoxide + iron oxide —> iron + carbon dioxide

calcium carbonate —> calcium oxide + carbon dioxide

calcium oxide + silicon dioxide —> calcium silicate

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21
Q

what is the function of the raw materials in the blast furnace?

A

iron ore (haematite): a compound that contains iron

coke: burns in air to produce heat, and reacts to form carbon monoxide (needed to reduce the iron oxide)
limestone: helps to remove acidic impurities from the iron by reacting with them to form molten slag
air: allows the coke to burn, and so produces heat and carbon monoxide

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22
Q

balance the equation for carbon + oxygen —> carbon dioxide

A

carbon + oxygen —> carbon monoxide

C + O2 —> CO2

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23
Q

balance the equation for carbon dioxide + carbon —> carbon monoxide

A

carbon dioxide + carbon —> carbon monoxide

CO2 + C —> 2CO

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24
Q

balance the equation for carbon monoxide + iron oxide —> iron + carbon dioxide

A

carbon monoxide + iron oxide —> iron + carbon dioxide

3CO + Fe2O3 —> 2Fe + 3CO2

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25
Q

balance the equation for calcium carbonate —> calcium oxide + carbon dioxide

A

calcium carbonate —> calcium oxide + carbon dioxide

CaCO3 —> CaO + CO2

limetsone decomposes to form calcium oxide and release carbon dioxide gas

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26
Q

balance the equation for calcium oxide + silicon dioxide —> calcium silicate

A

calcium oxide —> silicon dioxide + calcium silicate

CaO + SiO2 —> CaSiO3

calcium oxide reacts with silica impurities to form calcium silicate (a.k.a. slag)

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27
Q

label this diagram

A
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28
Q

which reeaction takes place in zone 1?

A

carbon + oxygen —> carbon dioxide

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29
Q

which reeaction takes place in zone 2?

A

carbon dioxide + carbon —> carbon monoxide

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30
Q

which reeaction takes place in zone 3?

A

carbon monoxide + iron oxide —> iron + carbon dioxide

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31
Q

why does slag float on top of iron?

A

slag is less dense

iron is more dense so it sinks

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32
Q

what is slag and how does it form in the Blast furnace?

A

slag is moletn waste and is formed when calcium oxide and silicon dioxide react together

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33
Q

what can slag be used for?

A

sement and making roads

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34
Q

what does a metal lose when it reacts with oxygen?

A

it loses its lustre (shiny surface)

it has tarnished

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35
Q

what is the general formula for when a metal reacts with oxygen?

A

metal + oxygen —> metal oxide

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36
Q

what is formed when a metal reacts with acid?

A

hydrogen gas and a salt are always formed

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37
Q

explain the reaction with aluminium and acid

A

aluminium forms a layer of oxide extremely quickly when exposed to air

this prevents the acid from reacting with the aluminium as quickly as it should

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38
Q

what is the general formula for when a metal reacts with acid?

A

metal + acid —> metal salt + hydrogen

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39
Q

why do some metals, like magnesium, not react in cold water?

A

there is not enough energy

it will react in hot water because the heat provides extra energy

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40
Q

how do you test for hydrogen?

A

put a lit splint in a test tube

if a squeky popping sound was heard then hydrogen is presented

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41
Q

what is the general formula for when a metal reacts with water?

A

metal + water —> metal hydroxide + hydrogen

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42
Q

complete this recativity table

A
43
Q

what can molten iron be used for

A

it can be pured onto crack and fractures on railway links to join them

44
Q

what are the properties of aluminium

A

low density

good electrical conductor

resistant to corrosion

easy to shape

strong when alloyed with other metals

non-magnetic

good thermal conductor

45
Q

why does aluminium have a low density?

A

atoms are not packed closely together

iron has a higher density

46
Q

why is aluminium very reactive?

A

reacts extremely quickly

forms aluminium oxide which prevents further reaction

does not corrode

47
Q

why is aluminium alloyed?

A

to become stronger

pure aluminium is soft

impurities mean aluminium atoms cannoyt slide easily over each other

48
Q

what is electrolysis?

A

using electricity to split or seperate atoms

used to extract highly reactive metals

49
Q

an anode is positive/negative

A

positive

50
Q

a cathode is positive/negative

A

negative

51
Q

negative ions move to which electrode?

A

positive anode electrode

52
Q

positive ions move to which electrode?

A

negative cathode electrode

53
Q

negative ions … electrons at the … electrode to become … - this is …

A

negative ions lose electrons at the positive electrode to become neutral - this is oxidation

54
Q

positive ions … electrons at the … electrode to become … - this is …

A

positive ions gain electrons at the negative electrode to become neutral - this is reduction

55
Q

from where is aluminium extracted?

A

its ore

56
Q

what is the definition of electrolysis?

A

the process by which ionic substances are decomposed (broken down) into simpler substances when an electric current is passed through them

the substance that is broken down is called the electrolyte

57
Q

what are the native metals in the reactivity series?

A

copper

silver

gold

platinum

58
Q

how are native metals extracted?

A

they won’t need to be extracted becuase they are so unreactive they are found on their own, not in a metal oxide

59
Q

what are the metals above carbon in the reactivity series?

A

potassium

sodium

calcium

magnesium

aluminium

60
Q

how are the metals above carbon in the reactivity series extracted?

A

electrolysis

they have more reactive than carbon and thus carbon cannot displace them

61
Q

what are the metals below carbon in the reactivity series?

A

zinc

iron

tin

lead

copper

62
Q

how are the metals below carbon in the reactivity series extracted

A

reduction

usually by heating them with carbon in the blast furnace (displacement recaction)

63
Q

in electolysis, what moves to the cathcode?

A

Al3+

64
Q

what reaction happens at the cathode?

A

Al3+ + 3 electrons- —> Al(s)

this is reduction

65
Q

what reaction happens at the anode?

A

O2- —> 0.5 O2 + 2 electrons-

this is oxidation

66
Q

what are the electrodes in electroylis made of

A

graphite

67
Q

why are electrodes made of graphite?

A

graphite is a good conductor of electricity

68
Q

why must the electrodes be replaced regularly?

A

oxygen produced burns the carbon electrode away (combustion)

69
Q

is electrolysis expensive or cheap and why?

A

expensive

electricty to burn fossil fuels

graphit is expensive

70
Q

what is cyrolite and why is it used?

A

it is an ore of aluminium

bauxite has a high melting point so cyrolite, with a low melting point, ismixed with bauxite so it dissolved in the cyrolite

it makes the process less expensive as it reduces some of the energy costs involved in extracting aluminium

71
Q

why is electrolysis dangerous

A

high amounts of electricty is used

72
Q

why does aluminium oxide need to be molten in electrolysis?

A

so the ions can move

so electrictity can pass throught it

73
Q

aluminium is a very good conductor of electricity and has a low density

give one use of aluminium which relies on both of these properties

A

pylons

74
Q

what elements can pure aluminium be alloyed to strengthen it?

A

silicon

copper

magnesium

75
Q

why does aluminium resist corrosion?

A

it has a very thin, but very strong, layer of aluminium oxide on its surface

this prevents anything else getting to the surface and reacting with it

76
Q

what products is aluminium useful for? whY?

A

because aluminium doesn’t corrode it’s useful for products that come in contact with water

e.g. drink cans - you wouldn’t want rust in your drink

77
Q

aluminium is much less/more dense than iron which makes it lighter/heavier

A

aluminium is much less ​dense than iron which makes it lighter

78
Q

because aluminium is less dense and therefore lighter than iron, it is useful when …

e.g. …

A

because aluminium is less dense and therefore lighter than iron, it is useful when the weight of the metal is important

e.g. in bicycle frames and aeroplanes

79
Q

what seven properties do iron and aluminium have in common?

A

they are both dense

they are both lustrous (shiny)

they both have high melting points

they both have a high tensile strencgth - they’re strong and hard to break

they are both malleable - can be hammered into a different shape

they are both good conductors of electricity

they are both good conductors of heat

80
Q

how is pig iron formed?

A

molten iron straight from the furnace that has been cooled rapidly and solidified by running it into sand moulds

81
Q

how is cast iron formed?

A

when pig iron (molten iron straight from the furnace that has been cooled rapidly and solidified by running it into sand moulds) is remelted and cooled under controlled conditions

82
Q

is cast iron pure? what percentage of carbon does it contain?

A

it is very impure iron, containing about 4% carbon as its main impurity

83
Q

what is cast iron a mixture of?

A

iron, carbon and silicon

84
Q

what are three properties of cast iron?

A

cast iron is very fluid when it is molten and doesn’t shrink much when it solidifies (this makes it ideal for making castings)

it is very hard

it is very brittle, tending to shatter if it is hit hard

85
Q

what are five uses of cast iron?

A

making castings

manhole covers

guttering

drainpipes

cylinder blocks in car engines

86
Q

what percentage of carbon does mild steel contain? what does this increase?

A

0.25%

this small amount of carbon increases the hardness and strength of the iron

87
Q

what are six uses of mild steel?

A

wire

nails

car bodies

ship building

girders (for construction)

bridges

88
Q

what is pure iron known as?

A

wrought iron

89
Q

what did wrought iron used to be for?

A

to make decorative gates and railings, but has now been largely replaced by mild steel

90
Q

explain the properties of wrought iron

A

the purity of wrought iron makes it very easy to work because it is fairly soft

the softness and lack of strength mean that it isn’t useful for structural purposes

91
Q

what percentage of carbon does high-carbon steel contain? what does increasing the carbon content do to the iron?

A

up to 1.5% carbon

increasing the carbon content makes the iron harder, but at the same time it gets more britt;e

92
Q

what are two uses of high-carbon steel?

A

cutting tools

masonry nails - designed to be hammered into concrete blcoks or brickwork where a mild steel nail would bend

if you miss a masonry nail, it tends to break into two bits because of its increased brittleness

93
Q

what is stainless steel?

A

an alloy of iron with chromium and nickel

94
Q

in stainless steel, what is the use of the chromium and nickel?

A

chromium and nickel form strong oxide layers, and these layers protect the iron

95
Q

is stainless steel resistant to corrosion? why?

A

stainless steel is very resistant to corrosion because the chromium and nickel form strong oxide layers that protect the iron

96
Q

what are six uses of stainless steel?

A

kitchen sinks

saucepans

knives

forks

gardening toolds

major uses for it in the brewing, dairy and chemical industries, where corrosion-resistant vessels are essential

97
Q

when does iron rust? how does this process work?

A

in the presence of oxygen and water

iron loses electrons to form iron (II) ions, Fe2+, which are then oxidised by the air to form iron (III) oxide, Fe3+

reactions involving the water produce the actual rust

98
Q

what accelerates rusting of iron?

A

when iron is in the presence of electrolytes such as salt

99
Q

What does rusting refer to?

A

many metals corrode, but it is only the corrosion of iron that is referred to as rusting

100
Q

What is trust and what is the formula of rust?

A

rust is a micture of iron (III) oxide and water

Fe2O3・xH2O where x is a number

101
Q

what three ways can you prevent rusting?

A

by using barriers

by alloying the iron

by using sacrificial metals

102
Q

how does preventing rusting by using barriers work?

A

by painting, coating it in oil or greese, or covering it in plastic to keep the water and and oxygen away from it

but once the coating is broken, the iron will rust

coating the iron with a metal below it in the reactivity series is just a barrier method

103
Q

what is an example of preventing rust by alloying the iron?

A

e.g. stainless steel

even if the surface is scratched, the stainless steel won’t rust

unfortunately, stainless steel is expensive

104
Q

how does preventing rusting by using sacrificial metals work?

A

Galvanised iron is iron that is coated with a layer of zinc

As long as the zinc layer is unscratched, it serves as a barrier to air and water. However, the iron still doesn’t rust, even when the surface is broken

Zinc is more reactive than iron, so it corrodes instead of iron. During the process, the zinc loses electrons to form zinc ions:

Zn (s) → Zn2+ (aq) + 2e-

Those electrons flow into the iron. Any iron atom which has lost electrons to form an ion immediately regains them. If the iron can’t form ions, it can’t rust

Chemisty (20 decks)

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