Question

A voltaic cell with an aqueous electrolyte is based on the reaction between Cd2 (aq) and Mg(s), producing Cd(s) and Mg2 (aq). Write half-reactions for the anode and cathode and then write a balanced cell reaction. Please include the states of matter in the equations.

Answer 1

Cd²⁺(aq) + 2 e⁻ → Cd(s)

Mg(s) → Mg²⁺(aq) + 2 e⁻

Cd²⁺(aq) + Mg(s) → Cd(s) + Mg²⁺(aq)

Step-by-step explanation:

A voltaic cell is composed of two half-reactions:

Reduction (cathode): Cd²⁺(aq) + 2 e⁻ → Cd(s)

Oxidation (anode): Mg(s) → Mg²⁺(aq) + 2 e⁻

Cd²⁺ reduces to Cd (the oxidation number decreases from 2 to 0), whereas Mg oxidizes to Mg²⁺ (the oxidation number increases from 0 to 2). We can get the overall cell reaction by adding both half-reactions:

Cd²⁺(aq) + 2 e⁻ + Mg(s) → Cd(s) + Mg²⁺(aq) + 2 e⁻

Cd²⁺(aq) + Mg(s) → Cd(s) + Mg²⁺(aq)