Question

Describe the bulk preparation of dihydrogen by electrolytic method. What is the role of an electrolyte in this process?

Answer 1

We know that Electrolysis is the process by which the ionic substances are broken down into simpler substances when an electric current is passed through it. The flow of ions is called Electricity. So, the compound must contain ions in it for the electrolysis process to work. The cations are reduced at cathode and the anions are oxidized at anode.

Complete Step by step answer: Let us see how the bulk preparation of ${H_2}$ by electrolytic method works: -
Here water is used for the preparation of dihydrogen. For the electrolysis of water, we can use acidified or alkaline water. Generally, $15 - 20\%$ of acid or base is used. For acid we can use ${H_2}S{O_4}$ and for base we can use $NaOH$ . For the electrodes we use platinum electrodes.
Now we see that cathode reduction is taking place, water is being reduced.
So, we write as:
At cathode: $2{H_2}O + 2e{H^ - } \to 2{H_2} + 2O{H^ - }$
We see that at anode oxidation is taking place, so $O{H^ - }$ ions will get oxidized.
So, we write as:
At anode: 2O{H^ - } \to {H_2}O + \dfrac{1}{2}{O_2} + 2{e^\\_}
Hence the net reaction will be:
${H_2}O(l) \to 2{H_2}(g) + \dfrac{1}{2}{O_2}(g)$
This is how the bulk preparation of dihydrogen takes place by electrolytic method.
The role of an electrolyte in electrolysis is to increase the conductivity. We know that the electrical conductivity of water is very low. Therefore, electrolysis of pure water takes place at a low rate. So, if an electrolyte such as acid or base is added to the process, the electrical conductivity of water increases and hence the rate of electrolysis also increases.

Note: Electrical conductivity of pure water is very low because water covalent bond is present so due to the presence of covalent bond ions are absent in it so electricity will not be conducted. Therefore, addition of electrolyte makes the ions available for the conductivity of electricity. Also, in the setup of electrolysis the two electrodes are separated from each other by an asbestos diaphragm which prevents mixing of ${H_2}$ and ${O_2}$ .