Question

To carry out the so-called "electrolysis of water", sulphuric acid is added to water. How does the addition of sulphuric acid produce a conducting solution?

Answer 1

When sulphuric acid is added to water, it becomes a good conductor, as the addition of sulphuric acid causes the dissociation of water molecules into H⁺ and OH⁻ ions, which are responsible for the conduction of electricity by pure water. The water thus obtained is called acidified water.

Answer 2

Pure water is non-electrolyte. All of it is made up of molecules. An electrolyte is added with a small quantity of sulphuric acid, causing the solution to ionise, giving the ions \[\ce{SO^2-_4}\] and H⁺. Thus, water was added with a small quantity of sulphuric acid containing the positive H⁺ ions and the negative \[\ce{SO^2-_4}\] and OH⁻ ions as follows:

\[\ce{H2O <=> H+ + OH-}\]

\[\ce{H2SO4 -> 2H+ + SO^2-_4}\]

Thus, the addition of H₂SO₄ helps in the ionisation of water.