Q46 / 180 · COMEDK 2019 · Chemistry
Electrolysis of brine gives a mixture of
- A$\mathrm{H}_{2}, \mathrm{Na}_{2} \mathrm{Cl}_{2}$
- Correct answerB$\mathrm{Cl}_{2}, \mathrm{H}_{2}, \mathrm{NaOH}$
- C$\mathrm{H}_{2}, \mathrm{O}_{2}, \mathrm{NaOH}$
- D$\mathrm{O}_{2}, \mathrm{Cl}_{2}, \mathrm{NaOH}$
Solution
Brine is a solution of sodium chloride and water. On electrolysis, it gives chlorine $\left(\mathrm{Cl}_{2}\right)$, hydrogen $\left(\mathrm{H}_{2}\right)$ and sodium hydroxide $(\mathrm{NaOH})$.
At cathode
$2 \mathrm{H}^{+}(a q)+2 e^{-} \longrightarrow \mathrm{H}_{2}$
$2 \mathrm{H}_{2} \mathrm{O}+2 e^{-} \longrightarrow \mathrm{H}_{2}+2 \mathrm{OH}^{-}(a q)$
At anode
$$
2 \mathrm{Cl}^{-} \longrightarrow \underset{\text { Chlorine }}{\mathrm{Cl}_{2}}+2 e^{-}
$$
The hydroxide ion, with the unchanged sodium ion, forms $\mathrm{NaOH}$.
$\mathrm{Na}^{+}+\mathrm{OH}^{-} \longrightarrow \underset{\substack{\text { Sodium } \\ \text { hydroxide }}}{\mathrm{NaOH}}$
Hence, the correct answer is option: 'B'.