Sodium amalgam is prepared by electrolysis of aqueous NaCl using 10 g mercury as cathode. How many F — Electrochemistry Chemistry Question

💡 Solution & Explanation

Let $x$ be the mass of Na deposited. The amalgam mass is $10 + x$. Given $x / (10 + x) = 0.187$. Solving for $x$: $x = 1.87 + 0.187x \Rightarrow 0.813x = 1.87 \Rightarrow x \approx 2.30$ g. Moles of Na = $2.30 / 23 = 0.10$ mol. Theoretical Faradays required = 0.10 F. Since current efficiency is 50%, actual Faradays required = $0.10 / 0.50 = 0.2$ F. Therefore, correct answer is B.