Electrochemistry

Basic Physical Chemistry Electrochemistry

1. What is emf? What are its units? 2. How many grams of gold could be plated out on the cathode of an electrolytic cell by the passage of 0.5 Amps of current through AuNO3 solution for 30 minutes? 3. A galvanic cell consists of a Mg electrode in 1.0 M Mg(NO3 )2 solution and a Ag electrode in a 1.0 M AgNO3 solution. Calculate the standard emf of this cell at 25°C. 4. Calculate the equilibrium constant, K eq , for the following reaction at 25 °C: Sn (s) +2Cu 2+ (aq)

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Sn 2+ (aq) + 2Cu + (aq)

5. Predict whether the following reaction would proceed spontaneously as written at 298 K: Co (s) + Fe2+ (aq) → Co 2+ (aq) + Fe (s) given that [Co2+] = 0.15M and [Fe 2+] = 0.68 M. 6. In an alkaline energy cell the overall cell reaction is as follows: Zn(s) + 2 MnO2(s) + 2 H2O → Zn(OH)2(s) + 2 MnO(OH) Write the reaction taking place at the cathode. 7. Draw the electrochemical cell: Pt (s) │ H2 (g) │ HCl(aq) │ AgCl (s) │ Ag(s) The following data apply to the above cell: E (cell) / V T/K 0.225 294.15 0.223 297.15 0.221 300.15 0.219 303.15

Write the half cell and net cell reactions and determine the values of E0, ∆G0, ∆S0, and ∆H0 at 298 K for the cell reaction. 8. Consider the cell Pt(s)|H2(g)|HCl(aq)|AgCl(s)|Ag(s), for which the cell reaction is 2 AgCl(s) + H2(g) → 2 Ag(s) + 2 HCl(aq). At 25°C and a molarity of HCl of 0.010 mol L 1, E = +0.4658 V. (a) Write the Nernst equation for the cell reaction. (b) Calculate ∆rG for the cell reaction.

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AMW (2012)