Electrochemistry 1 Question 20
20. The reaction,
$ \frac{1}{2} \mathrm{H} _{2}(g)+\mathrm{AgCl}(s) \rightleftharpoons \mathrm{H}^{+}(a q)+\mathrm{Cl}^{-}(a q)+\mathrm{Ag}(s) $
occurs in the galvanic cell
$(1985,1 M)$
(a) $\mathrm{Ag}|\mathrm{AgCl}(s)| \mathrm{KCl}$ (soln) $\left|\mathrm{AgNO} _{3}\right| \mathrm{Ag}$
(b) $\mathrm{Pt}\left|\mathrm{H} _{2}(g)\right| \mathrm{HCl}$ (soln) $\mid \mathrm{AgNO} _{3}$ (soln) $\mid \mathrm{Ag}$
(c) $\mathrm{Pt} \mid \mathrm{H} _{2}(g) \mathrm{HCl}$ (soln) $|\mathrm{AgCl}(s)| \mathrm{Ag}$
(d) $\mathrm{Pt}\left|\mathrm{H} _{2}(g)\right| \mathrm{KCl}($ soln $)|\mathrm{AgCl}(s)| \mathrm{Ag}$
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Answer:
Correct Answer: 20. (c)
Solution:
- In a galvanic cell, oxidation occur in the left hand electrode chamber and reduction in right hand electrode chamber. In the following cell.
$ \mathrm{Pt}\left|\mathrm{H} _{2}(g)\right| \mathrm{HCl}(l) || \mathrm{AgCl}(s) \mid \mathrm{Ag}(s) $
The cell reactions are :
$ \begin{gathered} \frac{1}{2} \mathrm{H} _{2}(g) \longrightarrow \mathrm{H}^{+}+e^{-} \quad \text { At anode } \\ \mathrm{AgCl}(s)+e^{-} \longrightarrow \mathrm{Ag}+\mathrm{Cl}^{-} \quad \text { At cathode }\\ \hline \text { Net }: \frac{1}{2} \mathrm{H} _{2}(g)+\mathrm{AgCl}(s) \longrightarrow \mathrm{H}^{+}+\mathrm{Ag}(s)+\mathrm{Cl}^{-} \\ \hline \end{gathered} $
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