Question

In an experiment, $20$ g of vanadium ($V$) oxide (molar mass$=182$) was reduced by excess of zinc dust in acidic solution to vanadium ($II$) ions. The required number of moles of iodine to reoxidise vanadium ($II$) to $V{O}^{2+}$ is :

• A. $0.22$
• B. $0.11$
• C. $0.30$
• D. $0.23$

Answer 1

The correct option is A $0.22$

According to given conditions:
$V_2{O}_5⟶V^{2+}⟶{VO}^{2+}$
Given,
$\underset{20g0.11mol}{V_2{O}_5}⟶\underset{0.22mol}{2V^{2+}}$
$\underset{+2}{2V^{2+}}+\underset{0}{2I_2}⟶\underset{+4}{{2VO}^{2+}}+\underset{-2}{4I^{-}}$
Thus, $\underset{0.11mol}{V_2{O}_5}\equiv 2V^{2+}\equiv 2{VO}^{2+}\equiv \underset{0.22mol}{2I_2}$
So, required number of moles of iodine to reoxidise is $0.22$.