6.4 Electrolysis in industry

Uses of electrolysis in industry
■ Uses of electrolysis in industry

	►	The extraction of metals
	►	The purification of metals
	►	Electroplating of metals

Extraction of metals
■ Extraction of metals

	►	Electrolysis can be used to extract metals from their ores.
	►	Used to extract metals that are more reactive than carbon - potassium, sodium, calcium, magnesium and aluminium.

■ Extraction of aluminium

	►	Extract from its ore, bauxite, which contains aluminium oxide(Al2O3)
	►	Molten aluminium oxide is mixed with crylolite to lower its melting point.
	►	Electrolysed by using carbon electrodes.
	►	Electrolyte: molten aluminium oxide At anode(+) At cathode(-) Ions present O2- Al3+ Ion selected for discharged Ion O2- selected for discharged Ion Al3+ selected for discharged Half-equation O2- → O2 + 4e- Oxygen gas is collected Al3+ + 3e- → Al Aluminium is produced

■ This video shows the processes of bauxite extraction.

Purification of metals
■ Purification of metals

	►	Electrolysis can be used to purify the impure metal.
	►	Cathode : pure metal, anode : impure metal
	►	Electrolyte : a salt containing the ions of the metal being purified.

■ Purification of copper

	►
	►	Electrolyte: Copper(II) Sulphate solution At anode(+) [Impure copper] At cathode(-) [Pure copper] Ions present SO42-, OH- Cu2+, H+ Ion selected for discharged Copper electrode ionizes to form ion Cu2+ Ion Cu2+ selected for discharged as it is lower position in electrochemical series. Half-equation Cu → Cu2+ + 2e- Copper electrode dissolve and its weight decrease. Cu2+ + 2e- → Cu Copper metal is deposited
	►	The impurities form a deposit below the anode.

■ This video shows the electrolytic refining of copper in an animated series.

Electroplating of metals
■ Electroplating of metals

	►	Electrolysis can be used to put a metallic coating on an object.
	►	Cathode : object to be plated, anode : metal that is used to plate the object.
	►	Electrolyte : a salt containing the ions of the metal used as anode.

■ Electroplating of metal spoon with silver

	►
	►	Electrolyte: Silver Sulphate solution At anode(+) [Silver] At cathode(-) [Spoon] Ions present SO42-, OH- Ag+, H+ Ion selected for discharged Silver electrode ionizes to form ion Ag+ Ion Ag+ selected for discharged as it is lower position in electrochemical series. Half-equation Ag → Ag+ + e- Silver is deposited on the electrode and its weight increase. Ag+ + e- → Ag Silver metal is deposited. A thin silver layer forms on the spoon

■ This video shows the electroplating of coin with nickel and copper.

← 6.3 Electrolysis of Aqueous Solutions

6.5 Voltaic Cell →

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