Electrochemistry - Result Question 103
51. Consider the cell,
$ Zn\left|Zn^{2+}(a q)(1.0 M) | Cu^{2+}(a q)(1.0 M)\right| Cu $
The standard reduction potentials are $0.350 V$ for
$ \begin{aligned} Cu^{2+}(a q)+2 e^{-} & \longrightarrow Cu \\ \text { and }-0.763 V \text { for } Zn^{2+}(a q)+2 e^{-} & \longrightarrow Zn \end{aligned} $
(i) Write down the cell reaction.
(ii) Calculate the emf of the cell.
(iii) Is the cell reaction spontaneous or not?
$(1982,2 M)$
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Solution:
- (i) The cell reaction is
$ Zn+Cu^{2+} \longrightarrow Zn^{2+}+Cu $
(ii)
$E _{\text {cell }}^{\circ}=E _{\text {cathode }}^{\circ}-E{\text {anode }}^{\circ}=0.350-(-0.763)=1.113 V$
$\because$ Both $Zn^{2+}$ and $Cu^{2+}$ are at unit concentrations,
$ E=E^{\circ}=1.113 V$
(iii) $ E _{\text {cell }}=1.113 V>0$
$\Delta G = -nEF < 0 $
Therefore, the cell reaction is spontaneous.
BETA
