The dand fblock elements - Result Question 43
####43. Assuming complete ionization, same moles of which of the following compounds will require the least amount of acidified $KMnO_4$ for complete oxidation
[2015 RS]
(a) $FeSO_4$
(b) $FeSO_3$
(c) $FeC_2 O_4$
(d) $Fe(NO_2)_2$
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Solution:
- (a) Considering the same moles of compounds $Fe^{2+} SO_4^{2-}$ only $Fe^{2+}$ is oxidised by $KMnO_4$. $\stackrel{(+6)}{SO_4^{2-}}$ in which sulphur is in highest oxidation state cannot be oxidised.
$ \begin{aligned} & Fe^{2+} SO_3^{2-} \xrightarrow[(+6)]{ } Fe^{3+} \\ & CO_3{ }^{2-} \longrightarrow SO_4{ }^{2-}+2 e^{-} \end{aligned} $
Sulphur can be oxidised to (+6) i.e to $SO_4^{2-}$
In $FeC_2 O_4 \longrightarrow Fe^{3+}$
Carbon can be oxidised to (+IV) i.e to $CO_2$
