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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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 :
$$ \begin{gathered} \frac{1}{2} \mathrm{H}{2}(g) \longrightarrow \mathrm{H}^{+}+e^{-} \quad \begin{array}{l} \text { At anode } \ \mathrm{AgCl}(s)+e^{-} \longrightarrow \mathrm{Ag}+\mathrm{Cl}^{-} \quad \text { At cathode } \end{array} \ \text { Net }: \frac{1}{2} \mathrm{H}{2}(g)+\mathrm{AgCl}(s) \longrightarrow \mathrm{H}^{+}+\mathrm{Ag}(s)+\mathrm{Cl}^{-} \end{gathered} $$
