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Extarction

Metals are extracted from ores using methods that depend on their reactivity, with less reactive metals extracted via reduction by coke and more reactive metals like aluminum extracted through electrolysis. Iron is extracted from haematite in a blast furnace, where coke provides heat and reduces iron(III) oxide to iron, while limestone is added to remove impurities. Bauxite is the ore for aluminum, which requires electrolysis for extraction due to its higher reactivity compared to carbon.

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23 views3 pages

Extarction

Metals are extracted from ores using methods that depend on their reactivity, with less reactive metals extracted via reduction by coke and more reactive metals like aluminum extracted through electrolysis. Iron is extracted from haematite in a blast furnace, where coke provides heat and reduces iron(III) oxide to iron, while limestone is added to remove impurities. Bauxite is the ore for aluminum, which requires electrolysis for extraction due to its higher reactivity compared to carbon.

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Justice Volney
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EXTRACTION OF METALS

Metals are extracted from their ores. An ore is the raw form of a metal obtained from the earth.

The method of extraction depends on the reactivity of the metal.

• ALL ABOVE ARE EXTRACTED VIA ELECTROLYSIS OF MOLTEN COMPOUND.


• ALL BELOW ARE EXTRACTED VIA REDUCTION BY COKE.

FACTS:

• The ore of iron is haematite (Fe2O3)


• The iron is extracted in a blast furnace.
DIAGRAM OF BLAST FURNACE:
DESCRIPTION OF EXTRACTION OF IRON FROM HAEMATITE IN BLAST FURNACE:

• Carbon in the form of coke is burnt to provide heat and produce carbon dioxide.
C + O2 → CO2

• Carbon dioxide is reduced to carbon monoxide:


C + CO2 →2CO

• Iron(III)Oxide is reduced by the carbon monoxide.


Fe2O3 + 3CO → 2Fe + 3CO2

• Thermal decomposition of limestone creates calcium oxide.


(limestone)CaCO3 → CaO(lime) + CO2

• Slag is formed.
CaO + SiO2(sand) → CaSiO3(slag)(calcium silicate)

Useful information:

• The limestone is added to remove the impurities (sand AKA silicon Dioxide).
• Calcium oxide is a base and silicon dioxide is an acidic oxide so they react.
• Uses of slag:
1. It floats on top of the iron to prevent re-oxidation.
2. It is used in roadmaking.
• The hot air provides the oxygen for the oxidation of coke.
• The highest waste gas is nitrogen.
• Carbon monoxide is formed via the reduction of carbon dioxide
• The carbon is provided by the coke
• The combustion of the carbon is needed to provide heat energy.
Aluminium

• The ore of aluminium is Bauxite : Al2O3. 2H2O.


• The name of pure Aluminium oxide is alumina. (Al2O3)
• We cannot use carbon to extract aluminium frfom bauxite since aluminium is more
reactive than carbon, therefore carbon is not able to displace it. So we use electrolysis.

Important things to note:

• The role of cryolite is to lower the melting point.


• The graphite (Carbon) electrodes must be constantly replaced since it reacts with the
oxygen to produce carbon dioxide.

At the anode:
2O2-(aq) → O2(g) + 4e-

At the cathode:
Al3+(aq) +3e- → Al(s)

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