Question

b) 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

Eo​ cell = Eo​ cath – Eo​ anode = +0.80 $-$ ($-$ 0.76) = 1.56 V

iii)ΔG = $-nFE$

If E$_o$ is positive, ΔG is negative, thus reaction is spontaneous.