Oxidation Number Chemistry Example 4

Solution

1. 1
   Left side: In $\text{Fe}_2\text{O}_3$, oxygen is $-2$, so Fe is $+3$. In $\text{CO}$, oxygen is $-2$, so C is $+2$.
2. 2
   Right side: Fe is $0$ (pure element). In $\text{CO}_2$, oxygen is $-2$, so C is $+4$.
3. 3
   Iron goes from $+3$ to $0$ — it gains electrons → reduced. Carbon goes from $+2$ to $+4$ — it loses electrons → oxidized. CO is the reducing agent; Fe₂O₃ is the oxidizing agent.