To a beaker containing 0.1 M – HCl, a little pure solid AgCl is added. Both a silver and a hydrogen electrode (P_H2 = 1.0 bar) are then placed in the solution. What is the approximate value of EMF mea

Question

To a beaker containing 0.1 M – HCl, a little pure solid AgCl is added. Both a silver and a hydrogen electrode (P_H2 = 1.0 bar) are then placed in the solution. What is the approximate value of EMF measured between the electrodes at 25°C? (Given: E°_Ag+\|Ag = 0.80 V and Ksp (AgCl) = 10^–10)

Prashant Kotian · Accepted Answer

Correct answer: B. The cell is Pt \| H2(1 bar) \| HCl(0.1M) \| AgCl(s) \| Ag. Anode: H2 -> 2H^+ + 2e^-. Cathode: AgCl + e^- -> Ag + Cl^-. Overall: 1/2 H2 + AgCl -> Ag + H^+ + Cl^-. Standard potential E°_cell = E°_AgCl/Ag = E°_Ag+/Ag + 0.0591 * log(Ksp) = 0.80 - 0.60 = 0.20 V. Using Nernst equation: E = 0.20 - 0.06 * log([H^+][Cl^-]) = 0.20 - 0.06 * log(0.1 * 0.1) = 0.20 - 0.06 * (-2) = 0.20 + 0.12 = 0.32 V. Therefore, correct answer is B.

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