Question

The composition of a sample of Wustite is $F{e}_{0.93}O$. What is the percentage of iron present as $F{e}^{3+}$ in total iron?

• A. $15.05\%$
• B. $25\%$
• C. $35\%$
• D. $45\%$

Answer 1

The correct option is A $15.05\%$

In pure iron oxide$\left(FeO\right)$, iron and oxygen are present in the ratio $1:1$

The number of $F{e}^{2+}$

Or

Number of $F{e}^{2+}$ ions missing $=0.07$

Each $F{e}^{2+}$ ion has $2$ positive charge, the total number of charge due to missing $\left(0.07\right)F{e}^{2+}$ $=0.07\times 2=0.14$

To maintain electrical neutrility, $0.14$ positive charge compensated by the presence of $F{e}^{3+}$ ions.

Therefore, replacement of one $F{e}^{2+}$ ion by one $F{e}^{3+}$ increases one positive charge, $0.14$ positive charge must be compensated by the presence of $0.14F{e}^{3+}$ ions.

In the short, $0.93Fe$ ions have $0.14$ $F{e}^{3+}$ ions

So, in 100 $Fe$ ions have

$\frac{0.14}{0.93}(\times 100)=15.05\%$ of $F{e}^{3+}$ ions .