Let's identify the oxidizing agents in each reaction individually.
Reaction (a):
[tex]\[ \text{Mg (s)} + \text{ZnSO}_4 \text{(aq)} \rightarrow \text{MgSO}_4 \text{(aq)} + \text{Zn (s)} \][/tex]
In this reaction, magnesium (Mg) is oxidized from Mg (s) to MgSO₄ (aq), which means it loses electrons. The substance that gains these electrons (and thus is reduced) acts as the oxidizing agent. The zinc ion in ZnSO₄ (aq) is reduced to Zn (s). Therefore, the oxidizing agent in this reaction is ZnSO₄.
Reaction (b):
[tex]\[ \text{Br}_2 \text{(aq)} + 2 \text{KI (aq)} \rightarrow 2 \text{KBr (aq)} + \text{I}_2 \text{(aq)} \][/tex]
In this reaction, iodide ions (I⁻) in KI are oxidized to iodine (I₂) while bromine (Br₂) is reduced to bromide ions (Br⁻) in KBr. The substance that is reduced (Br₂) is the oxidizing agent. Therefore, the oxidizing agent in this reaction is Br₂.
Reaction (c):
[tex]\[ 5 \text{Fe}^{2+} \text{(aq)} + \text{MnO}_4^{-} \text{(aq)} + 8 \text{H}^{+} \text{(aq)} \rightarrow 5 \text{Fe}^{3+} \text{(aq)} + \text{Mn}^{2+} \text{(aq)} + 4 \text{H}_2 \text{O (l)} \][/tex]
In this reaction, iron ions (Fe²⁺) are oxidized to iron ions (Fe³⁺), while permanganate ions ([tex]\(\text{MnO}_4^{-}\)[/tex]) are reduced to Mn²⁺ ions. The permanganate ion ([tex]\(\text{MnO}_4^{-}\)[/tex]) is thus the substance that gains electrons and is reduced, making it the oxidizing agent. Therefore, the oxidizing agent in this reaction is [tex]\(\text{MnO}_4^{-}\)[/tex].
To summarize:
- In reaction (a), the oxidizing agent is [tex]\(\text{ZnSO}_4\)[/tex].
- In reaction (b), the oxidizing agent is [tex]\(\text{Br}_2\)[/tex].
- In reaction (c), the oxidizing agent is [tex]\(\text{MnO}_4^{-}\)[/tex].
So, the oxidizing agents in the given reactions are:
- Reaction (a): [tex]\(\text{ZnSO}_4\)[/tex]
- Reaction (b): [tex]\(\text{Br}_2\)[/tex]
- Reaction (c): [tex]\(\text{MnO}_4^{-}\)[/tex]
