42. Exactly 500 mL of a 4.0 M aqueous solution is electrolysed entirely using a liquid Mercury () ca — Electrochemistry Chemistry Question

💡 Solution & Explanation

500 mL of 4.0 M $NaCl$ contains 2.0 moles of $Na^+$. On a mercury cathode, the high overvoltage of $H_2$ allows $Na^+$ to discharge, forming the amalgam $NaHg$. 2.0 moles of $Na^+$ form 2.0 moles of $NaHg$. Total Mass = $2.0 \times (23 + 200) = 446$ g.