Electrolysis of Aqueous Solutions

Which ions are discharged

• In an aqueous solution there are four ions: the two from the compound, and $\text{H}^+$ and $\text{OH}^-$ from water, because some water molecules break down
• At the cathode (negative): hydrogen is produced if the metal is more reactive than hydrogen; otherwise the metal is produced
  • Sodium chloride solution gives hydrogen; copper sulfate solution gives copper
• At the anode (positive): oxygen is produced from the hydroxide ions, unless the solution contains halide ions, when the halogen is produced
  • Sodium chloride solution gives chlorine; copper sulfate solution gives oxygen

• Test the products: hydrogen gives a squeaky pop with a lit splint; oxygen relights a glowing splint; chlorine bleaches damp litmus paper