Electrochemistry 1 Question 24
24. The standard reduction potentials at $298 \mathrm{K}$ for the following half cells are given :
$ \begin{aligned} \mathrm{Zn}^{2+}(a q)+2 e^{-} \rightleftharpoons \mathrm{Zn}(s) ; E^{\circ}=-0.762 \mathrm{V} \\ \mathrm{Cr}^{3+}(a q)+3 e^{-} \rightleftharpoons \mathrm{Cr}(s) ; E^{\circ}=-0.740 \mathrm{V} \end{aligned} $
$ \begin{aligned} 2 \mathrm{H}^{+}(a q)+2 e^{-} & \rightleftharpoons \mathrm{H} _{2}(g) ; E^{\circ}=0.000 \mathrm{V} \\ \mathrm{Fe}^{3+}(a q)+e^{-} & \rightleftharpoons \mathrm{Fe}^{2+}(a q) ; E^{\circ}=0.770 \mathrm{V} \end{aligned} $
Which is the strongest reducing agent?
(1981, 1M)
(a) $\operatorname{Zn}(s)$
(b) $\operatorname{Cr}(s)$
(c) $\mathrm{H} _{2}(g)$
(d) $\mathrm{Fe}^{2+}(a q)$
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Answer:
Correct Answer: 24. (a)
Solution:
- Lower the value of $E^{\circ}$, stronger the reducing agent.
