Production and Uses of
Metals
Additional Science
Chapter 8
CHEMISTRY 2
Metallic minerals
The least reactive metals occur in an uncombined
form within the Earth’s crust.
e.g. gold
The other metals exist as ores in combination with
other elements such as oxygen and sulphur.
Pyrite
Haematite
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(a mineral of iron sulphide)
(a mineral of iron - oxide)
Metals are produced from their ores by a
process called reduction.
Iron pan
The reactivity series of metals
Different metals have different reactivities. A more reactive metal will remove
oxygen from the oxide of a less reactive metal when a mixture of the two is
heated.
When a mixture of powdered aluminium and iron(III) oxide is ignited by a
high temperature fuse, molten iron is formed. This reaction is called the
thermit reaction and is used to weld sections of railway track.
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A mixture of
aluminium and
iron(III) oxide
reacting together
railway track
crucible
railway track
The reactivity series of metals
This table shows the reactivity series of common metals,
and how they are extracted from their ores.
Reactivity
Strong
Element
Extraction method
K (Potassium)
Na (Sodium)
Reaction with acid
Too dangerous
Electrolysis
Ca (Calcium)
Mg (Magnesium)
Releases hydrogen and dilute
hydrochloric acid.
Zn (Zinc)
Fe (Iron)
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Sn (Tin)
Cu (Copper)
Weak
Ag (Silver)
Chemical reduction
Doesn’t release hydrogen and
dilute hydrochloric acid.
Extracting iron from its ore
Chemical reduction with carbon
1. Raw materials (iron ore, coke and
limestone) are added at the top of the furnace.
2. Blasts of hot air (which give the furnace its
name) are blown in near the bottom of the
furnace.
Load if iron
ore, coke and
limestone
3. Oxygen in the blasts of air reacts with coke
(carbon) to form carbon monoxide.
2C + O2  2CO
Gas outlet
This reaction is very exothermic and the
temperature in the furnace reached 2000°C.
The blast
furnace
1000°C
4. As the carbon monoxide rises up the
furnace, it reacts with the iron ore (iron(III)
oxide to form iron.
1500°C
Fe2O3 + 3CO  2Fe + 3CO2
2000°C
Blasts of hot
air
Blasts of hot
air
Molten slag
(impurities)
Outlet for
molten
iron
Outlet for the slag
Molten iron
5. Molten iron runs to the bottom of
the furnace. It is tapped off from
time to time.
6. The molten iron is used to make
steel or poured into moulds to
solidify. The large chunks of iron
formed are called ‘pigs’ so this
metal is called ‘pig iron’.
Steel – properties and uses
Iron from the blast furnace is very brittle because it contains up to
4.5% carbon.
Most of this iron is converted to steel, which is far more useful, by removing
most of the carbon. Mild steel contains approximately 0.5% carbon.
Hard steel contains up to
1.5% carbon.
Car bodies
machines
Domestic
appliances
It is possible to treat steel .
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Chapter 8
Heat treatment
Creating alloys with other metals
Stainless steel
(chromium and nickel)
Very hard steel
(tungsten)
Tough steel
(manganese)
Tinplate
Recycling steel
Steel is recycled on a large scale.
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Saves up to 50% of
energy costs
Helps to conserve
iron ore
Cuts down the emission
of greenhouse gases
Electrolysis – background
Electrodes
Conducting
liquid –
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electrolyte
Electrolysis is a chemical reaction. Current enters the
electrolyte via two solid conductors called electrodes.
Electrolysis – background
Positive
electrode
ion+ ionion- ion+
ion+ ion-
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ion- ion+
Negative
Electrode
Electrolyte
The anode is the positive electrode, and the cathode is the negative
electrode.
The positive ions (cations) move towards the negative electrode, and the
negative ions (anions) move towards the positive electrodes.
Electrolysis – extraction of reactive metals
Remove impurities by
chemical method
Bauxite – a rock
containing
aluminium
Aluminium oxide
powder (alumina),
with a very high
melting point
Electrolysis of aluminium oxide (alumina)
carbon anodes
crust of solidified
electrolyte
1. Aluminium oxide is dissolved in
molten cryolite (about 950°C).
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2. Oxygen gas is formed at the
aluminium
carbon anodes, and at that high
oxide in
molten cryolite temperature the anodes react with
oxygen, burning away and having to
be replaced from time to time.
Molten aluminium
tap hole
insulated cell casing
carbon lining to cell
acting as the cathode
3. Aluminium in the form of a molten
metal forms at the cathode.
4. The tap hole is used to
collect the aluminium, the
crust needs to be broken to
add more aluminium oxide.
The equations for the reaction:
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Positive aluminium ions are attracted to
the negative cathode, where they gain
electrons and form aluminium metal.
Al3+
+3e
Al
2O2-
-4e
O2
Negative oxide ions are attracted to
the positive anode, where they lose
electrons and form oxygen gas.
Locating aluminium works
The raw materials and the product
need to be transported easily
A lot of electricity is required
for producing the metal via
electrolysis
A good transport
network
in and out
Build aluminium works
near cheap sources
of electricity
Port
Railway links
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Roads
Hydroelectric
Power Source
Nuclear Power Station
Properties of aluminium
light
strong
density of
2.7g/cm3
resistant to corrosion
layer of aluminium oxide (this prevents
corrosion even though the metal is very
reactive)
Using aluminium
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Use
1. High voltage power cables for the
Reason
Light, resistant to corrosion
National Grid
2. Saucepans and kitchen foil
Good conductor of heat, non toxic
3. Window frames and greenhouses
Strong and light
4. Drinks cans
Strong and non toxic
5. Aeroplane and car bodies
Strong and resistant to corrosion
Properties of copper
excellent conductor of
electricity and heat
malleable
ductile
non toxic
Use of copper
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Use
Reason
1. Wires in electrical circuits
Good conductor of heat
2. Saucepans
Good conductor of heat and non toxic
3. Jewellery
Malleable and ductile, attractive colour and
lustre
4. Water pipes
Non toxic and malleable
5. Produces the alloy bronze (copper
+ tin) and brass (copper + zinc)
Properties of titanium
good conductor of heat and electricity
light
strong
tough
high melting point
non toxic
low density
non corrosive
Using titanium
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Use
Reason
1. Aircraft industry
Light, tough, non corrosive
2. Surgical equipment
Light, tough, non corrosive
3. Artificial joints, plates for bone
fractures
Non toxic, light, tough, non corrosive
4. Jewellery
Non toxic
5. Titanium dioxide is the basis of
white paint.
The consequences of metal extraction
Disadvantages
Advantages
When the ore runs out, the
mine workings may be
abandoned causing a
deterioration of the
landscape.
Extraction and processing
of minerals creates
employment.
Importing metals is very
expensive for the
country.
Sometimes less useful and
toxic metals are found with the
ones that are needed.
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Important for the economy
(Economic boom in the UK
during Industrial
Revolution).
Processing minerals have
a detrimental effect on the
environment.
Fluctuations in the cost of
metals can affect the
economy.
A lot of electricity is needed
to produce aluminium.
Many minerals are
sulphides – produce
sulphur dioxide (the gas
that causes acid rain).