Question

20 ml of 0.02 M $KMn{O}_4$ was required to completely oxidise 10 ml of oxalic acid solution. What is the molarity of the oxalic acid solution?

• A. 4.0 M
• B. 0.1 M
• C. 0.4 M
• D. 1.0 M

Answer 1

The correct option is B 0.1 M

The concerned reaction is
$\underset{\left[\text{For}KMn{O}_4\right]}{2KMn{O}_4}+3H_{2}S{O}_4+\underset{\left[\text{For oxalic acid}\right]}{5(COOH{)}_2}\to K_{2}S{O}_4+2MnS{O}_4+10C{O}_2+8H_{2}O$
$V_1=20ml{V}_2=10ml$
$M_1=0.02M{M}_2=?$
$n_1=2n_2=5$
We know the relation
$\frac{M_1{V}_1}{n_1}=\frac{M_2{V}_2}{n_2}$
$\Rightarrow \frac{0.02\times 20}{2}=\frac{M_2\times 10}{5}$
$M_2=\frac{0.02\times 20\times 5}{10\times 2}=0.1M$
Hence option (a) is correct.