Question

A button cell used in watches function as following Zn(s) + Ag₂O(s) + H₂O(l) \(\rightleftharpoons\) 2Ag(s) + Zn²⁺(aq) + 2OH^-(aq). If half cell potentials are \({Zn^{2+}_{ (aq)} + 2e\to Zn(s); E^{\circ} = -0.76V}\) \({Ag2O_{(s)} + H2O_{(l)} + 2e\to 2Ag_{(s)} + 2OH^{-}_{(aq)};}\) \(E^{\circ} = 0.34V\)

• A. 1.34 V
• B. 1.10 V
• C. 0.42 V
• D. 0.84 V

Answer 1

The Correct Option is B

\({ Zn^{2+}(aq) + 2e^-\to Zn(s); E^{\circ} = -0.76 V}\)
\({Ag2O(s) + H2O(l) + 2e^- \to 2Ag(s) + 2OH^-(aq);}\)
\(E^{\circ} = 0.34 \, V\)
\({Zn(s) + Ag2O(s) + H2O(l) \to 2Ag(s) + Zn^{+2} (aq) + 2OH^-(aq); E_{cell} = ?}\)
\({ E^{\circ}_{cell} = (E^{\circ}_{R.P.})_{cathode} - (E^{\circ}_{R.P.})_{anode}}\)
\({E^{\circ}_{cell} = 0.34 - (-0.76) = 1.10 V}\)
\({E_{cell} = E^{\circ}_{cell} = 1.10V}\)

So, the correct answer is (B): 1.10 V