Electrolysis

Question 1

In solution electrolysis, how can you predict what will be produced at the anode?

Answer 1

Anode (positive electrode) attracts anions (negative ions)

If a halide ion (Cl⁻/Br⁻/I⁻)is present, that element is produced as per normal:
e.g. 2Br⁻→Br₂+ 2e⁻

Otherwise, O₂and H₂O are produced according to the following half-equation:
4OH−→O₂+ 2H₂O + 4e⁻

Question 2

In solution electrolysis, how can you predict what will be produced at the cathode?

Answer 2

Cathode (negative ions) attracts cations (positive ions)

If the metal is less reactive than hydrogen, that element is produced as per normal:
e.g. Cu²⁺+ 2e⁻→Cu

Otherwise, H₂ is produced according to the following half-equation:
2H⁺+ 2e⁻→H₂