Question

What are the products of electrolysis of an aqueous solution of dilute sulphuric acid? Explain with reasons.

Answer 1

During the electrolysis of dilute sulphuric acid (H₂SO₄), the products formed are hydrogen gas (H₂) at the cathode, Oxygen gas (O₂) at the anode.

Reasons:

At the cathode, H⁺ ions from the acid are reduced to form hydrogen gas.

\[\ce{2H{^{+}_{(aq)}} + 2e- -> H2_{(g)}}\]

Hydrogen ions are preferentially discharged because they have a higher reduction potential than other available cations.

At the anode, water molecules are oxidised to form oxygen gas.

\[\ce{2H2O_{(l)} -> O2_{(g)} + 4H{^{+}_{(aq)}} + 4e−}\]

\[\ce{SO^2-_4}\] ions are not oxidised due to their low tendency to lose electrons (high oxidation potential). Therefore, water is discharged, producing oxygen.