Question

The number of moles of acidified $KMn{O}_4$ required to convert two moles of sulphite ion into sulphate ion is:

• A. $5/2$
• B. $5$
• C. $2/5$
• D. $4/5$

Answer 1

Answer: (D)

$4/5$

The chemical reaction can be written as:

$2KMn{O}_4+5H_{2}S{O}_3⟶K_{2}S{O}_4+2MnS{O}_4+2H_{2}S{O}_4+2H_{2}O$

For $5$ moles of sulphite ion, $2$ moles of $KMn{O}_4$ is required.

Therefore, to convert $2$ moles of sulphite ion $\frac{2\times 2}{5}$ moles of $KMn{O}_4$ is required.