Answer : [tex]O_2[/tex] is the oxidizing agent and Fe is the reducing agent.
Explanation :
Reducing agent : It is defined as the agent which helps the other substance to reduce and itself gets oxidized. Thus, it will undergo oxidation reaction.
Oxidizing agent : It is defined as the agent which helps the other substance to oxidize and itself gets reduced. Thus, it will undergo reduction reaction.
The balanced redox reaction is :
[tex]4Fe+3O_2\rightarrow 2Fe_2O_3[/tex]
The half oxidation-reduction reactions are:
Oxidation reaction : [tex]Fe\rightarrow Fe^{3+}+3e^-[/tex]
Reduction reaction : [tex]O_2+4e^-\rightarrow 2O^{2-}[/tex]
In order to balance the electrons, we multiply the oxidation reaction by 4 and reduction reaction by 3 then added both equation, we get the balanced redox reaction.
Oxidation reaction : [tex]4Fe\rightarrow 4Fe^{3+}+12e^-[/tex]
Reduction reaction : [tex]3O_2+12e^-\rightarrow 6O^{2-}[/tex]
[tex]4Fe+3O_2\rightarrow 2Fe_2O_3[/tex]
In this reaction, [tex]'Fe'[/tex] is the reducing agent that loses an electron to another chemical species in a redox chemical reaction and itself gets oxidized and [tex]'O_2'[/tex] is the oxidizing agent that gain an electron to another chemical species in a redox chemical reaction and itself gets reduced.
Thus, [tex]O_2[/tex] is the oxidizing agent and Fe is the reducing agent.