Question

In electrolysis of water:
(a) Name the gas collected at cathode and anode.
(b) Why is the volume of one gas collected at one electrode is double of anode?
(c) Why are few drops of dilute ${{H}_{2}}S{{O}_{4}}$ added to water?

Answer 1

Hint: Electrolysis is a technique used to drive a nonspontaneous reaction by applying direct current. Electrolysis is used to separate elements from naturally occurring molecules (ores) by using an electrolytic cell.

Complete step by step answer:
- The electrolysis of water in the form of a chemical reaction is as follows.
\[2{{H}_{2}}O\to 2{{H}_{2}}+{{O}_{2}}\]
- In electrolysis of water hydrogen and oxygen gases are released.
(a) The gas which is released at cathode is hydrogen, ${{H}_{2}}$ and the gas released at anode is oxygen, ${{O}_{2}}$.
(b) From the above chemical reaction we can see that two moles of water undergoes electrolysis and produces two moles of hydrogen and one mole of oxygen gas. The reason for producing two moles of hydrogen and one mole of oxygen is that the water contains two hydrogens and one oxygen in its molecular formula.
Therefore after electrolysis the water volume of one gas collected at one electrode is double (hydrogen gas) of anode (oxygen gas).
(c) In electrolysis we will pass some direct current to make the reaction happen.
- We know that pure water is a bad conductor of electricity. So, we pass direct current through the water it won’t pass.
- So, to make the electrolysis to happen we should add few drops of sulphuric acid (${{H}_{2}}S{{O}_{4}}$) to water in electrolysis of water.


Note: Electrolysis of water used to generate oxygen for the space station. Electrolysis used in industries to purify many metals from their ores and used to one metal on another metal through the electroplating process.