Electrochemistry Result Question 47
47. The standard reduction potential of $\mathrm{Cu}^{2+} / \mathrm{Cu}$ and $\mathrm{Ag}^{+} / \mathrm{Ag}$ electrodes are 0.337 and 0.799 V respectively. Construct a galvanic cell using these electrodes so that its standard emf is positive. For what concentration of $\mathrm{Ag}^{+}$will the emf of the cell, at $25^{\circ} \mathrm{C}$, be zero if the concentration of $\mathrm{Cu}^{2+}$ is $0.01 M$ ?
(1990, 3M)
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Answer:
Correct Answer: 47. $(1.57 \times 10^{-9} \mathrm{M})$
Solution:
- The galvanic cell is : $\mathrm{Cu}\left|\mathrm{Cu}^{2+} | \mathrm{Ag}^{+}\right| \mathrm{Ag}$
Cell reaction $\mathrm{Cu}+2 \mathrm{Ag}^{+} \rightleftharpoons \mathrm{Cu}^{2+}+2 \mathrm{Ag}; E^{\circ}=0.462 \mathrm{~V}$
$E =0=0.462-\frac{0.0592}{2} \log \frac{(0.01)}{\left[\mathrm{Ag}^{+}\right]^2} $
$\Rightarrow \left[\mathrm{Ag}^{+}\right] =1.57 \times 10^{-9} \mathrm{M}$
BETA
