Reactivity Series
The reactivity series affects how easily a metal can be extracted from its ore.
K
Metals ABOVE CARBON are
extracted by ELECTROLYSIS.
Electrolysis
Na
Ca
Metals BELOW CARBON
are extracted by heating
them with carbon in a
BLAST FURNACE. This is
called REDUCTION.
Mg
Al
Heating with
carbon
Zn
Fe
Sn
Pb
These LOW REACTIVITY
metals usually don’t need to
be extracted because they are
so unreactive you can find
them NATIVE (as an element).
Cu
Ag
Au
Pt
1
Ores
An ore is a naturally occurring rock that contains enough metal (or metal
compound) to make extraction worthwhile.
The more reactive the metal, the more difficult and expensive it is to extract.
Ores are often oxides, carbonates or sulphides. They are all finite resources.
Examples:
← Iron ore: hematite
Aluminium ore: bauxite →
2
Extraction of Iron
Iron is extracted in a blast furnace from its ore hematite (contains iron(III)
oxide).
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Zone 3
The reduction of iron(III) oxide by
carbon monoxide.
Zone 2
The reduction of carbon dioxide to
carbon monoxide.
Cao site
Zone 1
The burning of carbon (coke) to provide
heat and produce carbon dioxide.
3
Extraction of Aluminium
Aluminium is extracted from its ore bauxite (contains aluminium oxide).
A 203
More reactive metals (like aluminium) are above carbon in
the reactivity series, so they cannot be extracted by
reduction using carbon.
Instead, aluminium is extracted by electrolysis.
Electrolysis is the process of decomposing a compound by
sending an electric current through it.
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4
Extraction of Aluminium
Before adding it to the cell, Al2O3 is mixed with cryolite to lower its melting
point.
A layer of graphite around the inside of the cell forms the negative electrode. The
positive electrodes are also made from graphite.
In the cell, the mixture of Al2O3 and cryolite is melted and a current is passed
through.
Molten Al is formed at the negative electrode, where the Al3+ ions are reduced to
Al atoms. The liquid Al runs to the bottom of the cell, where it is removed.
At the positive electrode, the O2– ions are oxidised and form oxygen gas. The
graphite in the positive electrodes react with oxygen, producing carbon dioxide
and so the electrodes must be replaced regularly.
Reaction at the positive electrode (anode): 2 02
Reaction at the negative electrode (cathode): A1
Overall reaction:
602
441
602
4
02
ᵗ
3 e
302
451 3
Al
xc
25
44
4
5
Extraction of Zinc
Zinc is extracted from zinc blende (zinc ore that contains zinc sulfide).
2n
ᵗ
52
The zinc sulfide is roasted in air, where it reacts with oxygen to form zinc oxide
and sulfur dioxide.
The zinc oxide is then reduced by carbon monoxide (produced from
carbon/coke) in a furnace to form zinc.
Zinc is produced as a vapour, which rises to the top of the furnace and is then
condensed to form liquid zinc.
2 ZnS + 3 O2 → 2 ZnO + 2 SO2
ZnO + CO → Zn + CO2
6
Extraction of Zinc
Isis
Compare and contrast the pros and cons of the extraction of metals via
electrolysis vs. reduction with carbon.
Reduction with carbon
elentricity from renewable
sources can be used
C
is cheap
slog
can be used
only metals which are less
reactive than carbon can be redu
releases
O
Electrolysis
greenhousegas
needs high temperatures
Uses non renewable resources
can produce metals which are
more reactive than carbon
uses
a
lot of energy
expensive
high temperatures ones need
to be melted
7
Recycling of Metals
Metals can be recycled instead of being extracted from ores.
On the next slide, list the possible advantages and disadvantages of recycling
metals (compared to extraction).
9
Recycling of Metals
Advantages:
Saves
natural
resources
reduces greenhouse gas emissions
reduces waste
uses
less energy
reduces landfill waste
Disadvantages:
metals need to
be
collected and transported
10
Exam Question
1)
88 1
iron
Isaitt
loss of
CO is oxidised
sat
water
oxygen
12
Mark Scheme
1)
13
Exam Question
2)
14
Exam Question
2)
15
Mark Scheme
2)
16
Exam Question
3)
17
Mark Scheme
3)
18
Mark Scheme
3)
19
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