Which metal has to be obtained from its ore by electrolysis because it is too reactive to be released by heating with carbon?
Question 1 Report
Which metal has to be obtained from its ore by electrolysis because it is too reactive to be released by heating with carbon?
Answer Details
Carbon can only remove oxygen from the oxide of a metal that is less reactive than carbon itself. Metals above carbon in the reactivity series hold their oxygen too strongly, so they have to be extracted by electrolysis of the molten ore, where an electric current supplies the electrons directly.
Aluminium sits well above carbon, so aluminium oxide is electrolysed after being dissolved in molten cryolite, and Al3+ ions gain electrons at the cathode: Al3+ + 3e- → Al.
Iron and lead both lie below carbon, so their oxides are reduced by carbon or carbon monoxide in a furnace, which is much cheaper. Copper is lower still and is easily obtained this way. Remember the rule: above carbon means electrolysis.
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