Question

What is the oxidation state of Fe in \( \mathrm{Fe_3O_4} \)?

• A. \( +2 \)
• B. \( +3 \)
• C. \( +8/3 \)
• D. \( +4 \)

Hint:

For compounds with mixed oxidation states, calculate the average oxidation number by summing the contributions of each oxidation state and dividing by the total number of atoms.

Answer 1

The Correct Option is C

Step 1: Understanding the composition of \( \mathrm{Fe_3O_4} \):

\( \mathrm{Fe_3O_4} \) is a mixed oxide composed of \( \mathrm{FeO} \) and \( \mathrm{Fe_2O_3} \). In this structure:

• \( \mathrm{FeO} \) contains iron with an oxidation state of \( +2 \).
• \( \mathrm{Fe_2O_3} \) contains iron with an oxidation state of \( +3 \).

Step 2: Calculating the average oxidation state:

The formula for \( \mathrm{Fe_3O_4} \) contains 3 atoms of iron, where:

\[ \text{Oxidation states:} \quad 1 \, (\mathrm{Fe}^{+2}) + 2 \, (\mathrm{Fe}^{+3}). \]

The total oxidation number for all iron atoms is:

\[ (+2) + 2(+3) = +8. \]

The average oxidation state of iron is:

\[ \frac{+8}{3}. \]

Thus, the oxidation state of \( \mathrm{Fe} \) in \( \mathrm{Fe_3O_4} \) is \( \mathbf{+8/3} \).