Question

Consider the following equation, which represents the reaction in the extraction of chromium from its ore: \[ \text{Fe}_2\text{O}_3 + 4\text{Na}_2\text{Cr}_2\text{O}_7 + 3O_2 \rightarrow 2\text{Fe}_2\text{O}_3 + 4\text{Na}_2\text{CrO}_4 + 3O_2 \] Which of the following statements about the oxidation states of the substances is correct?

• A. The iron has been reduced from +3 to +2
• B. The chromium has been oxidized from +3 to +2
• C. The chromium has been oxidized from +3 to +4
• D. The carbon has been oxidized from +2 to +4

Hint:

Oxidation refers to the increase in oxidation state, and reduction refers to a decrease.

Answer 1

The Correct Option is C

Step 1: Understand the oxidation states.
The reaction shows that chromium is being oxidized from +3 in \( \text{Na}_2\text{Cr}_2\text{O}_7 \) to +4 in \( \text{Na}_2\text{CrO}_4 \), while iron remains in the same oxidation state.
Step 2: Conclusion.
Thus, the correct statement is that chromium has been oxidized from +3 to +4.
Final Answer: \[ \boxed{C} \]