Answer to Question #164125 in Physical Chemistry for Parul

Question

The cell reaction for a galvanic cell is given below: 

 Zn(s) + 2Ag+

 (aq) →Zn2+ (aq) + 2Ag(s) 

i) Write the half-cell reactions at the anode and the cathode. 

ii) Calculate the value of cell emf under standard conditions;. 

 iii) Will the reaction be spontaneous as written?

Answer 1

i)  

Oxidation at anode: Zn(s) → Zn²⁺ (aq) + 2e−

Reduction at cathode: Ag⁺ (aq) + e⁻ → Ag (s)

ii)

Ag: E = +0.80 V

Zn: E = -0.76 V

E⁰_cell = E⁰_cath – E⁰_anode = +0.80 –(-0.76) = 1.56 V

iii)

ΔG = -nFE

If E⁰ is positive, ΔG is negative, thus reaction is spontaneous.