Question

A solution of $10ml\frac{M}{10}FeS{O}_4$ was titrated with $KMn{O}_4$ solution in acidic medium. The amount of $KMn{O}_4$ used will be :

• A. 5 ml of 0.1 M
• B. 10 ml of 0.1 M
• C. 10 ml of 0.5 M
• D. 10 ml of 0.02 M

Answer 1

Answer: (D)

Given: The $10ml$ of $\frac{M}{10}FeS{O}_4$ is titrated with $KMn{O}_4.$
To Find: Amount of $KMn{O}_4$ used.
Reaction:
$Mn{O}_4^{-}+5F{e}^{2+}+8H^{+}\to 5F{e}^{3+}+M{n}^{2+}+4H_{2}O$
Hence, 1 mole of $KMn{O}_4$ is required to titrate 5 moles of $FeS{O}_4$.
Moles of $FeS{O}_4$ titrated =Molality $\times$ Volume
$=10ml\times \frac{M}{10}=1m$ mole.
The number of moles of $KMn{O}_4$
used $=\left(\frac{\text{ Moles of }FeS{O}_4}{5}\right)$
$=\frac{1mill\text{ mole }}{5}=0.2m$ mole.
So, $0.2m$ mole $=10ml\times 0.02MKMn{O}_4$.
Therefore, $10ml$ of $0.02MKM{O}_4$ is required to titrate the $FeS{O}_4$ solution.