Question

Which of the following options is incorrect for electrolysis of brine solution?

• A. Sodium hydroxide can be produced by this process.
• B. Gas given out at cathode burns with a pop sound.
• C. Gas given out at anode is used for making bleaching powder.
• D. Gas given out at cathode is used for making bleaching powder.

Answer 1

The correct option is D Gas given out at cathode is used for making bleaching powder.

Aqueous solution of sodium chloride is called brine. When electricity is passed through brine solution, the following reaction takes place:

$2\mathrm{NaCl}\left(\mathrm{aq}\right)+2H_{2}O\left(l\right)\to 2\mathrm{NaOH}\left(\mathrm{aq}\right)+{\mathrm{Cl}}_2\left(g\right)+H_2\left(g\right)$

Chlorine gas is given out at anode and hydrogen gas given out at the cathode. Sodium hydroxide is also produced by this process.

The chlorine produced is used for the manufacture of bleaching powder. (${\text{CaOCl}}_2$)

$\mathrm{Ca}(\mathrm{OH}{)}_2\left(\mathrm{aq}\right)+{\mathrm{Cl}}_2(\mathrm{aq})\to {\mathrm{CaOCl}}_2(\mathrm{aq})+H_{2}O(l)$

The hydrogen gas burns a matchstick with a pop sound.