R3.2.15 Electrolysis of aqueous solutions

What happens when aqueous solutions are electrolysed

Water can be oxidized at anode or reduced at cathode

Water half-reactions (reduction/oxidation)

In reduction reaction, twice the volume of hydrogen gas is produced when compared to oxygen gas

Electrolysis of water

NaOH added to increase pure water’s low conductivity

Water reduced at cathode due to more positive standard electrode potential

Determining half-reaction at cathode

Two possible choices for half-reactions at cathode

Reduction of element with more positive standard electrode potential occurs at cathode

Determining half-reaction at anode

Two possible choices for half-reactions at anode

Oxidation of element with higher concentration occurs at anode

Electrolysis of CuSO₄ with copper electrodes

Copper reduced at cathode

Copper oxidized at anode