This document discusses the extraction of metals from ores. It begins by stating that most metals are found in nature combined with other elements in compounds like oxides, sulfides, and carbonates. It then explains different extraction methods including heating alone, heating with carbon or carbon monoxide, and electrolysis. As an example, it describes the extraction of iron from iron ore in a blast furnace. The document also briefly discusses alloys and their important uses.

2. After completing this topic you should be able to :
• State ores are naturally occurring compounds of metals.
• State the less reactive metals, including gold, silver and copper, are found
uncombined in the Earth’s crust and the more reactive metals have to be extracted
from their ores.
• Explain why some metals can be obtained from metal oxides by heat alone; some
metal oxides need to be heated with other substances, e.g. carbon or carbon
monoxide; other metals cannot be obtained by these methods.
• Describe how iron is produced from iron ore in the Blast Furnace.
• Give examples of the important uses of alloys, e.g. brass, solder, “stainless” steel.
• Describe the extraction of metals from compounds as a reduction reaction.
N5
• Describe the reaction taking place at the negative electrode during
electrolysis for the extraction of metal as a reduction reaction. N5

3. The metals we use are obtained from rocks in the Earth’s crust.
Most metals are too reactive to exist in a pure uncombined form in the Earth’s
crust. Metals are found as in rocks metal compounds. The usual metal
compounds found in rocks are OXIDES, SULPHIDES and CARBONATES.
A few metals are found uncombined, as they are very unreactive. Metals, which are
found uncombined are called NATIVE METALS.
The native metals are:
Gold
(Au)
Platinum
(Pt)
Silver
(Ag)
Copper
(Cu)

4. NAME OF ORE NAME OF METAL
COMPOUND IN ORE
METAL IN ORE
Iron pyrites
(Fools Gold)
iron sulphide
Malachite
copper carbonate
Galena
lead sulphide
iron
copper
lead

5. NAME OF ORE NAME OF METAL
COMPOUND IN ORE
METAL IN ORE
aluminium oxide
iron(III) oxide
tin(IV) oxide
aluminium
iron
tin
Haematite
(Blood Stone)
Cassiterite
Bauxite

7. A large number of ores contain .
To extract a metal from an ore requires heat. Some metal oxides break down by
heat alone.
HEATING AND
(II)
HEAT
(I)
HEAT
breaks
down on heating to
form and
.
Heating has no effect
on .

8. +
+22 4
heat
heat
The is changed to a . To do this each has to
. This change is reduction.
Breaking down a compound into its elements from which it is made is called a
DECOMPOSITION REACTION.
decomposes on heating to form silver and oxygen.
+( )22 4
+
heat

9. WITH CARBON
with can be extracted by just heating their compounds.
is too reactive to be extracted by HEAT ALONE.
with can be extracted by heating their compounds
with carbon.
HEATING WITH CARBON
+
carbon
HEAT
After the reaction some
can be seen in
the beaker.
The products of the
reaction are
and CARBON
.
cold
water
Drop hot test tube
into cold water

10. Carbon helps remove the from the . The transfers
to the carbon forming carbon .
+ carbon + carbon
+ C C+
heat
heat
2 2
+ C C+2 2
The is changed to a . To do this each
has to . This change is reduction.
+
heat

11. Iron is extracted from its ore using carbon. The
reaction requires a lot of heat. To provide the
necessary heat the reaction is carried out in a
BLAST FURNACE.
Iron ore, coke
(carbon) and
limestone enter
the furnace from
the top of the
furnace.
The extraction of the iron happens in 3 stages.
STAGE 1: The coke (carbon) burns to produce
carbon dioxide CO2.
STAGE 1
C(s) + O2(g) CO2(g)
STAGE 2: The CO2 from stage 1 reacts with more
carbon to form carbon monoxide CO.
CO2(g) + C(s) 2CO(g)
STAGE 2
STAGE 3
STAGE 3: The CO from stage 2
reacts with iron(III) oxide Fe2O3 in
the iron ore removing the oxygen.
Fe2O3(s) + 3CO(s) 2Fe(l) + 3CO2(g)
Molten iron
flows to the
bottom of the
furnace.
Fe(l)

12. + carbon + carbon
+ C C+
heat
heat
3 2 3
( )2( )3 + C C+3 2
heat
3
The is changed to a . To do this each has to
. This change is reduction.
+

13. AND
The terms and originates from the extraction of metals
industry. These terms were used for centuries before atoms and electrons were
discovered.
An reaction is a reaction where a reactant .
An reaction is a reaction where a reactant
.
The extraction of iron from in the shows these
original definitions of and .
+ carbon + carbon
+ C C+
heat
heat
3 2 3
The has to produce . It has been
.
The carbon has an to produce carbon
. It has been .

14. Aluminium is too reactive to extract by heating with carbon or carbon
monoxide.
All reactive metals from aluminium upwards on the reactivity series are extracted
using ELECTROLYSIS.
Bauxite
The bauxite ore is purified to produce pure
aluminium oxide Al2O3. This is called
ALUMINA.
Solid ionic compound do not conduct
electricity as their ions are not free to move.
Alumina is dissolved in
, as it has a lower melting point than
aluminium oxide, which reduces the energy
needed for the extraction.
This solution is electrolysed and
forms at the negative
electrode.
Alumina

15. +-
Carbon positive
electrodes.
Carbon lining as
the negative
electrode.
Solution of
aluminium oxide
in molten cryolite.
Molten aluminium
collects at the bottom.
The moves to the negative electrode where it
and changes to an . This change is reduction.
+

16. Often the properties of a pure metal makes it unsuitable for the purposes we wish to
use it. Iron, for example, rusts easily and is quite brittle.
The properties of metals can be altered, by adding
small quantities of other metals, or non-metals, to
make a new metal called an ALLOY.
An ALLOY is a metal made by mixing different
metals, or metals with non-metals.
Alloys improve the properties of metals by making them harder, stronger and more
resistant to corrosion.
ALLOY CAR WHEEL
SOLDER STAINLESS STEEL BRONZE

17. Mild steel
Stainless
steel
12-carat
gold
Duralumin
Bronze
Brass
Cupro-
nickel
iron carbon Girders, cars,
tools
iron chromium, nickel Sinks, taps,
cutlery
gold silver, copper Jewellery
aluminium copper, magnesium Aircraft bodywork
copper tin Coins, knives,
swords
copper zinc Ornaments, bells
musical
instruments
copper nickel “Silver” coins
ALLOY MAIN METAL
OTHER ELEMENTS
PRESENT
USES