In the standard reduction half-reaction for oxygen gas in an acidic medium, , how many moles of elec — Electrochemistry Chemistry Question

💡 Solution & Explanation

Balancing the half-reaction for oxygen reduction in acid: $O_2$ goes to $H_2O$. Oxygen changes oxidation state from $0$ to $-2$. Two oxygen atoms per $O_2$ molecule mean $2 \times 2 = 4$ electrons are gained. The balanced equation is $O_2(g) + 4H^+(aq) + 4e^- \rightarrow 2H_2O(l)$. Thus, $4$ moles of electrons are transferred.