Question

One mole of ferric oxalate is titrated with acidified potassium permanganate solution. In this, :

• A. $3$ mol of potassium permanganate are required
• B. $1.2$ mol of potassium permanganate are required
• C. oxalate ion is oxidised to carbondioxide
• D. ferric ion is oxidised to ferrate ($VI$) ion

Answer 1

Answer: (B), (C)

$1.2$ mol of potassium permanganate are required
oxalate ion is oxidised to carbondioxide

1 mole of ferric oxalate will give 2 moles of Fe(III) ions and 3 moles of oxalate ions.
$\underset{1mol}{{Fe}_2{\left(C_2{O}_4\right)}_3}\rightleftharpoons 2{Fe}^{3+}+\underset{3mol}{3C_2{O}_4^{2-}}$
Fe(III) is already in the oxidized form. It cannot be oxidized further. Hence, the option (d) is incorrect.
$2Mn{O}_4^{-}+5C_2{O}_4^{2-}⟶10C{O}_2+2{Mn}^{2+}$
Oxidation of 5 moles of oxalate ions will require 2 moles of potassium permanganate.
$5mol{C}_2{O}_4^{2-}\equiv 2molMn{O}_4^{2-}$
Hence, the number of moles of potassium permanganate required for the oxidation of 3 moles of oxalate ions will be $\frac{2\times 3}{5}=1.2mol$.
Thus, the option (a) is incorrect and option (b) is correct.
In this reaction, oxalate ion is oxidized to carbon dioxide. Thus, option (c) is correct.