A disproportionation reaction involves a substance that acts as both an oxidizing agent and a reducing agent, producing higher and lower oxidation states of the same element in the products. Which of the following disproportionation reactions are spontaneous under standard conditions? Calculate ΔG^o and K at 25^oC for those reactions that are spontaneous under standard conditions.

a. 2Cu⁺(aq)  →  Cu²⁺(aq) + Cu(s)

b. 3Fe²⁺(aq)  →  2Fe³⁺(aq) + Fe(s)

c. HClO₂(aq)  →  ClO₃^-(aq) + HClO(aq) (unbalanced)

Use the half reactions:

ClO3 ^{2 +} 3H⁺ + 2e^-  →  HClO₂ + H₂O ϐ^o = 1.21 V

HClO2 ⁺ 2H⁺ + 2e^-  →  HClO + H₂O ϐ^o = 1.65 V