Electrochemistry - Result Question 54
####56. Standard potentials $(E^{\circ})$ for some half-reactions are given below :
[1997]
(1) $Sn^{4+}+2 e^{-} \to Sn^{2+} ; E^{o}=+0.15 V$
(2) $2 Hg^{2+}+2 e^{-} \to Hg_2^{2+} ; E^{o}=+0.92 V$
(3) $PbO_2+4 H^{+}+2 e^{-} \to Pb^{2+}+2 H_2 O$;
$ E^{\circ}+1.45 V $
Based on the above, which one of the following statements is correct?
(a) $Sn^{4+}$ is a stronger oxidising agent than $Pb^{4+}$
(b) $Sn^{2+}$ is a stronger reducing agent than $Hg_2{ }^{2+}$
(c) $Hg^{2+}$ is a stronger oxidising agent than $Pb^{4+}$
(d) $Pb^{2+}$ is a stronger reducing agent than $Sn^{2+}$
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Solution:
- (b) $Sn^{2+} \longrightarrow Sn^{4+}+2 e^{-} ; E^{0}=-0.15 V$
$Hg_2^{2+} \longrightarrow 2 Hg^{2+}+2 e^{-} ; \quad E^{0}=-0.92 V$
Thus, $Sn^{2+}$ can more easily get oxidized than $Hg_2{ }^{2+}$ or $Sn^{2+}$ is stronger reducing agent than $Hg_2{ }^{2+}$.
