2.23C: Explain How the Method of Extraction of a Metal is Related to its Position in the Reactivity Series, Illustrated by Carbon Extraction for Iron and Electrolysis of Aluminium

REACTIVITY SERIES:

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METAL	METHOD OF EXTRACTION
MOST REACTIVE	EXTRACTED BY ELECTROLYSIS OF THE     MOLTEN CHLORIDE OR MOLTEN OXIDE
POTASSIUM
SODIUM
LITHIUM
CALCIUM
MAGNESIUM
ALUMINIUM
CARBON
ZINC	EXTRACTED BY HEATING WITH A     REDUCING AGENT SUCH AS CARBON OR     CARBON MONOXIDE IN A BLAST FURNACE
IRON
HYDROGEN
COPPER
SILVER	FOUND AS PURE ELEMENTS
GOLD
LEAST REACTIVE

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CARBON EXTRACTION (FOR ELEMENTS BELOW CARBON):

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CARBON EXTRACTION OF IRON

Diagram showing the Carbon Extraction of Iron

RAW MATERIALS: Iron Ore (Haematite), Coke, Limestone and Air

EXPLANATION: Iron Ore, Coke and Limestone are mixed together and fed into the top of the blast furnace, while hot Air is blasted into the bottom of the blast furnace Oxygen in the Air reacts with the Coke to form Carbon Monoxide: C (s)    +    O2 (g)    →    CO2 (g) Carbon Dioxide reacts with Coke to form Carbon Monoxide: CO2 (g)    +    C (s)    →    2CO (g) Carbon Monoxide reduces the Iron (III) Oxide in the Iron Ore to form Iron, which will melt and collect at the bottom of the furnace, where it is tapped off: Fe2O3 (s)    +    3CO (g)    →    2Fe (l)    +    3CO2 (g) Calcium Carbonate in Limestone decomposes to form calcium Oxide: CaCO3 (s)    →    CaO (s)    +    CO2 (g) Calcium Oxide reacts with Silicon Dioxide - which is an impurity in the Iron Ore, to form Calcium Silicate which melts and collects as molten slag on top of the molten Iron and is tapped off separately: CaO (s)    →    SiO2 (s)    +    CaSiO3 (l)

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ELECTROLYSIS EXTRACTION (FOR ELEMENTS ABOVE CARBON):

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EXTRACTION OF ALUMINIUM BY ELECTROLYSIS

Diagram showing the Extraction of Aluminium by Electrolysis

RAW MATERIALS: Aluminium Ore (Bauxite)

EXPLANATION: Bauxite is purified to produce Aluminium Oxide Al2O3 Aluminium Oxide has a very high melting point so is dissolved in molten Cryolite to form a electrolyte with a lower melting point, as well as a better conductor of electricity than Molten Aluminium Oxide Reaction at the Negative Electrode: Aluminium melts and collects at the bottom of the cell and is tapped off: Al3+    +    3e-    →    Al Reaction at the Positive Electrode: 2O2-    -    4e-    →    O2 Some of Oxygen produced at the positive electrode then reacts with the Graphite (Carbon) to produce Carbon Dioxide Gas: C (s)    +    O2 (g)    →    CO2 (g) *This means that the positive electrode gradually burns away and needs to be replaced at regular intervals