Question

Choose the correct option regarding the chlor-alkali reaction:

• A. $C{l}_2$ is given off at the cathode.
• B. Brine solution decomposes when electricity is passed through it.
• C. Brine is a solution of $HCl$ and $NaCl$.
• D. $H_2$ is given off at the anode.

Answer 1

The correct option is B Brine solution decomposes when electricity is passed through it.

The process of separating substances into their elements by passing direct electric current through their solution is known as electrolysis. This process can be used to get Na and Cl from brine since brine is a solution of sodium chloride in water.

The reaction for chlor-alkali process is given as :

$2NaCl+2H_{2}O⟶2NaOH+C{l}_2+H_2$

The reaction occurring at the anode is given as :
$C{l}^{-}\left(aq\right)⟶\frac{1}{2}C{l}_2+e^{-}$

The reaction taking place at the cathode is given as :
$N{a}^{+}\left(aq\right)+e^{-}⟶NaNa+H_{2}O⟶NaOH+\frac{1}{2}{H}_2$

So, chlor-alkali reaction is a process used to produce chlorine and sodium hydroxide (caustic soda) by the decomposition of brine solution by application of electricity.