Question

A button cell used in watches functions as following.

Zn_(s) + Ag₂O_(s) + H₂O_(l) → 2Ag_(s) + Zn²⁺_(aq) + 2OH_(aq).

If half cell potentials are Zn²⁺_(aq) + 2e^- → Zn_(s) E° = – O.76V

Ag₂O_(s) + H₂O_(l) + 2e^- 2Ag_(s) + 2OH^-_(aq) E⁰ = 0.34V

The cell potential will be ……….. 

(a) 1.10V 

(b) 0.42V 

(c) 0.84V 

(d) 1.34V

Answer 1

(a) 1.10V

Cell potential = E_cathode – E_anode

= 0.34 – (- 0.76) 

= 0.34 + 0.76 

= 1.10V