(a)(i) Explain briefly each of the following terms: I. anode; II. cathode.

(ii) Sodium and aluminium are extracted by the electrolysis of molten sodium chloride and alumina respectively. Write balanced equations for the reactions at the anode and cathode during the extraction of: I. sodium; II. aluminium.

(iii) Explain briefly why extraction of aluminium is considered environmentally friendly while that of sodium is not.

 

(b) Consider the reaction represented by the following equation:

K\(_2\)Cr\(_2\)O\(_7\) + HC1--> KCI + CrCl\(_3\) + H\(_2\)O + Cl\(_2\)

(i) Explain briefly why this reaction is redox.

(ii) Write balanced half equations for the reaction.

(iii) Write the over-all balanced reaction equation.

 

(c) During the electrolysis of molten Al\(_2\)O\(_3\), a current of 6A was passed through the electrolyte for 1 hr. 30 mins. Calculate the mass of aluminium deposited at the cathode.