General Principles and Processes of Isolation of Elements
In order to obtain 1 tonne of aluminium, 4 tonnes of bauxite, 150 kg of sodium hydroxide and 600 kg of graphite is required. The aluminium compound in bauxite is aluminium oxide and the main impurity is iron (III) oxide, Aluminium is obtained by the electrolysis of aluminium oxide dissolved in cryolite.
(i) Write the formulae of cryolite.
(ii) Write down the word which correctly completes the following sentence.
By dissolving aluminium oxide in cryolite a ____ (conducting/ non conducting) solution is produced.
(iii) Why is so much graphic required for the electrolytic process?
(iv) Write the equation for the reaction which takes place at cathode.