Question

Standard electrode potential of half-cell reactions are given below
$C u^{2+}+2 e^{-} \rightarrow C u ; E^{\circ}=0.34\, V $
$Z n^{2+}+2 e^{-} \rightarrow Z n ; E^{\circ}=-0.76 \,V$
What is the emf of the cell?

• A. + 1.10 V
• B. −1.10 V
• C. −0.42 V
• D. +0.42 V

Answer 1

Answer: (A)

$Z n \rightarrow Z n^{2+}+2 e^{-}$(oxidation half-reaction)
$C u^{2+}+2 e^{-} \rightarrow C u$ (reduction half-reaction)
Emf of the cell $=$ standard oxidation potential of zinc
electrode $+$ standard reduction potential of Cu electrode
$=0.76 \,V +0.34\, V =1.10 \,V$