Question

A solution containing $N{a}^{\oplus },N{O}_3^{\ominus },C{l}^{\ominus }$, and $S{O}_4^{2-}$ ions, all at unit concentrations, is electrolyzed between nickel anode and plantinum cathode. As the current is passed through the cell :

• A. pH of the cathode increases
• B. Oxygen is the major product at anode
• C. Nickel is deposited at cathode
• D. Chlorine is the major product at anode

Answer 1

Answer: (A), (D)

The correct options are
A pH of the cathode increases
D Chlorine is the major product at anode

At cathode : Reduction of $N{a}^{\oplus }$ does not occur but reduction of $H_{2}O$ occurs to give $\stackrel{\ominus }{O}H$ and $H_2\left(g\right)$, so pOH decreases and pH increases. Hence, option A is correct

At anode : Oxidation of $C{l}^{\ominus }$ ions occur to give $C{l}_2\left(g\right)$. Likewise, oxidation of $N{O}_3^{\ominus }$ and $S{O}_4^{2-}$ does not occur, but oxidation of $H_{2}O$ occurs to give $H^{\oplus }$ ions and $H_2$ (g). So pH decreases at anode. Also, chlorine forms hence, option D is correct.