Question

An aqueous solution of $N{{a}_{2}}S{{O}_{4}}$ containing a small amount of HP h is electrolyzed using Pt-electrodes. The color of solution after some time will be:
A. Remain colorless
B. Change from pink to colorless
C. Change from colorless to pink
D. Remain pink

Answer 1

$N{{a}_{2}}S{{O}_{4}}$ is generally known with the name sodium sulfate or sulfate of soda. It is an inorganic compound which is generally white in color and it is highly soluble in water. Mainly used in the manufacturing of detergents and in paper pulping.

Complete step by step answer:
Electrolysis is the process in which an electric current is passed through a substance to effect a chemical change. The chemical change is explained in the way in which the substance loses or gains an electron i.e. oxidation or reduction takes place. The process is carried out in an electrolytic cell an apparatus which consists of positive and negative electrodes held apart and dipped into a solution containing positively and negatively charged ions.
Now we have to go through the process of electrolysis of $N{{a}_{2}}S{{O}_{4}}$ solution
At cathode: $2{{H}^{+}}+2{{e}^{-}}\to {{H}_{2}}$ or $4{{H}^{+}}+4{{e}^{-}}\to 2{{H}_{2}}$
At anode: $2{{H}_{2}}O\to {{O}_{2}}+4{{e}^{-}}+4{{H}^{+}}$
The pH or color will be depend on the concentration of ${{H}^{+}}$ ion but as shown in reactions takes place at anode and cathode we can observe that concentration of ${{H}^{+}}$ does not change so we can say that it remains colorless.

Note: Electric current i.e. electrons enters through the negatively charged electrode known as cathode and components of the solution travel to cathode further combine with the electrons and are reduced and if components of the solution travel to the other electrode called anode then it gets oxidized.