Question

During electrolysis of an aqueous solution of sulphuric acid between platinum electrodes, two types of anions migrate towards the anode but only one of themis discharged:

(a) Name the two anions,

(b) Name the main product of the discharge of anion at the anode and write the anode reaction,

(c) Name the product at the cathode and write the reaction.

(d) How you notice any change in colour. State why?

(e) Why this electrolysis, is considered as an example of catalysis?

Answer 1

(a) Two anions are SO 2⁻4 and OH^-.

(b) OH^- is discharged at anode and the main product of the discharge of OH^- is O₂

Reaction is :

OH^- ⟶ OH + e^-

4OH ⟶ 2H₂O + O₂

(c) The product formed at cathode is hydrogen. The reaction is :

H⁺ + e^- ⟶ H

H + H ⟶ H₂

(d) No change in colour is observed.

(e) Dilute sulphuric acid catalyse the dissociation of water molecules into ions, hence electrolysis of acidified water is considered as an example of catalysis.