Electrolysis of Na2SO4

An electric current is passed through a dilute solution of Na2SO4 using platinum electrodes. Current is conducted through movement of ions. A few drops of universal indicator solution are added to the solution to indicate the ion movement. It is red in acid, blue in a base and green in neutral solutions

At the positive electrode, the equation for the reaction is 2H2O → O2 + 4H(+) + 4e(-). This results in the release of H(+) ions which turn the indicator solution red. Also we see from the equation that oxygen gas is evolved from the reaction.

At the negative electrode the equation is 2H2O +2e(-)  → H2 + 2OH (-). Hydrogen gas is evolved at this electrode. The indicator turns blue as a result of the basic OH (-) ions. Twice as much H2 is evolved in comparison to O2

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