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; use data from Table 7.1. 

 iii) Will the reaction be spontaneous as written?

Answer 1

i) Oxidation at anode: $Zn(s) → Zn^{2+} (aq) + 2e^{−}$

Reduction at cathode: $Ag+ (aq) + e^{−} → Ag (s)$

ii)Ag: E = +0.80 V

Zn: E = -0.76 V

$E_0cell = E_0cath – E_0anode = +0.80 –(-0.76) = 1.56 V$

iii)$ΔG = -nFE$

If $E_0$ is positive, ΔG is negative, thus reaction is spontaneous.