During the electrolysis process aluminium is deposited at the cathode and oxygen is liberated at the anode. Some of the oxygen reacts with the carbon in the graphite to form carbon dioxide. by consuming the anode slowly. Thus the anodes have to be replaced periodically or a number of graphite electrode as anodes have to be used.
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Q. (i) Name the solution used to react with Bauxite as a first step in obtaining pure aluminium oxide, in the Baeyer's process.
(ii) Write the equation for the reaction where the aluminium oxide for the electrolytic extraction of aluminium is obtained by heating aluminium hydroxide.
(iii) Name the compound added to pure alumina to lower the fusion temperature during the electrolytic reduction of alumina.
(iv) Write the equation for the reaction that occurs at the cathode during the extraction of aluminium by electrolysis.
(v) Explain why it is preferable to use a number of graphite electrodes as anode instead of a single electrode, during the above electrolysis.
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