Question

The composition of a sample of wustite is ${Fe}_{0.92}O$. What percentage of the iron is present in the form of $Fe\left(III\right)$?

• A. $5$%
• B. $7.08$%
• C. $15.05$%
• D. $23.6$%

Answer 1

The correct option is C $15.05$%

From the valency of $Fe\left(II\right)$ and $Fe\left(III\right)$ it is clear that three $Fe\left(II\right)$ ions will be replaced by two $Fe\left(III\right)$ causing a loss of one iron.

Total loss of iron from one molecule of $FeO=1-0.93=0.07$

Hence, total $Fe\left(III\right)$ present in one molecule of $FeO=2\times 0.07=0.14$

Total number of $Fe\left(II\right)$ and $Fe\left(III\right)$ present in one molecule of $FeO=0.93$.

Hence, percentage of $Fe\left(III\right)=\frac{0.14\times 100}{0.93}$$=15.05$%