Question

The number of moles of $KMn{O}_4$ that will be needed to react completely with one mole of ferrous oxalate in acidic solution is:

• A. $\frac{2}{5}$
• B. $\frac{3}{5}$
• C. $\frac{4}{5}$
• D. $1$

Answer 1

Answer: (B)

$\frac{3}{5}$

$2KMn{O}_4+5C_2{O}_4+16H^{+}\to 2M{n}^{2+}+2K^{+}+10C{O}_2+8H_{2}O$

$KMn{O}_4+5F{e}^{2+}+8H^{+}\to K^{+}+5F{e}^{3+}+M{n}^{2+}+4H_{2}O$

From the above equations, it is observed that 3 moles of $KMn{O}_4$ will be needed to react completely with five moles of ferrous oxalate in acidic solution.

No. Of equivalents of KMnO${}_4=$no. Of equivalents of FeC${}_2$O${}_4$

Equiv. Of KMnO${}_4=n\times$ no. Of moles$=5\times x$.

Equivalents of FeC${}_2$O${}_4=3\times 1=3$

$5x=3$

$x=3/5$

Hence, the correct option is $\text{B}$.