Electrolysis of an aqueous solution of sodium sulfate produces hydrogen and oxygen. What is the source of the hydrogen and the oxygen produced during the electrolysis of aqueous sodium sulfate solution?

In the electrolysis of an aqueous solution, there are ions from the dissolved salt and also ions from the water itself (H₂O ⇌ H⁺ + OH⁻). In the case of sodium sulfate (Na₂SO₄) solution, the ions present are Na⁺, SO₄²⁻, H⁺, and OH⁻.\n- At the negative electrode, H⁺ ions are discharged in preference to Na⁺ ions (because hydrogen is less reactive than sodium), producing hydrogen gas.\n- At the positive electrode, OH⁻ ions are discharged in preference to SO₄²⁻ ions, producing oxygen gas and water.\nTherefore, both the hydrogen and oxygen products come from the breakdown of water.