Question

$1$ mol of ferric oxalate is oxidised by $x$mol of ${Mn{O}_4}^{-}$ in acidic medium. The ratio $\frac{x}{y}$ is :

• A. $2:1$
• B. $1:2$
• C. $3:1$
• D. $1:3$

Answer 1

The correct option is A $2:1$

In acidic medium, two moles of permanganate oxidizes $5$ moles of oxalic acid.
Also, $1$ mole of permanganate oxidizes $5$ moles of Fe(II) ions.
$1$ mole of ferrous oxalate gives $1$ mole of Fe(II) ions and $1$ mole of oxalate ions.
It will require $\frac{1}{5}$ moles of permanganate for the oxidation of Fe(II) ions and $\frac{2}{5}$ moles of permanganate for the oxidation of oxalate ions.
Total permanganate required is $\frac{1}{5}+\frac{2}{5}=\frac{3}{5}=y$.
$1$ mole of ferric oxalate gives $2$ moles of Fe(III) ions and $3$ moles of oxalate ions.
It will require $\frac{3\times 2}{5}$ moles of permanganate for the oxidation of oxalate ions.
Total permanganate required is $\frac{6}{5}=x$.
The ratio $\frac{x}{y}=\frac{\frac{6}{5}}{\frac{3}{5}}=2:1$.