Question

In the electrolysis of acidulated water,_________ gas is evolved at the anode

Answer 1

The gas evolved at anode in the acidulated water is oxygen gas. At cathode hydrogen gas is evolved. In electrolysis an ionic substance is broken down into smaller ions. Acidulated water is water containing some acid. Different reactions result in formation of the oxygen and hydrogen gas.

Complete answer:
Electrolysis is the process by which ionic substances are decomposed into simpler substances when an electric current is passed through them. in electrolysis a direct electric current through the compound in a fluid form. During electrolysis, the cations get reduced at the cathode and anions get oxidized at the anode. We can understand this by taking an example of water that has salt in it. So in the container water is present. In water salt is present. two rods one of the cathode and another of the anode are dipped in this solution. And a direct current is made to pass through the solution. So during the electrolysis, the molten sodium chloride will get decomposed into sodium and chlorine. The container in which electrolysis is performed is called an electrolytic cell.
Acidulated water is water that contains some sort of acid. The ions present in an acidified solution are $S{O_4}^{2 - },{\text{ }}O{H^ - }\;and{\text{ }}{H^ + }$.When the electrolysis of acidulated water takes place, the gas that is released is oxygen gas. In acidified water, an acid ${H^ + }$ is present which gets attracted towards the cathode. This ${H^ + }$ gains an electron and forms hydrogen gas. The $O{H^ - }$ ions present get attracted towards the anode. These lose electrons and turn into oxygen gas.

Note:
During the electrolysis of acidified water or acidulated water the reaction taking place at cathode is ${H^ + }\; + {\text{ }}{e^ - }\; \to {\text{ }}H$ then this H combines with other H to become hydrogen gas $H{\text{ }} + {\text{ }}H{\text{ }} \to {\text{ }}{H_2}$. The reaction taking place at anode is $O{H^ - }\; \to {\text{ }}OH{\text{ }} + {\text{ }}{e^ - }$ then these $O{H^ - }$ ions come together at anode to form oxygen gas $4OH{\text{ }} \to {\text{ }}2{H_2}O{\text{ }} + {\text{ }}{O_2}$.