Explanation:
Oxidizing agent is the reactant in the chemical reaction which oxidizes others and reduces itself.
Reducing agent is the reactant in the chemical reaction which reduces others and oxidizes itself.
(a) In the given reaction :-
[tex]8H^+_{(aq)} + [Cr_2O_7]^{2-}_{(aq)} + 3SO_3^{2-}_{(aq)}\rightarrow 2Cr^{3+}_{(aq)} + 3SO_4^{2-}_{(aq)} + 4H_2O_{(l)}[/tex]
Cr exists in +6 oxidation state in [tex][Cr_2O_7]^{2-}[/tex] and forms [tex]Cr^{3+}[/tex] in which it has +3 oxidation state.
Thus, it is reduced in the chemical reaction. Thus, [tex][Cr_2O_7]^{2-}[/tex] is oxidizing agent and [tex]SO_3^{2-}[/tex] is the reducing agent.
(b) In the given reaction :-
[tex]NO_3^-_{(aq)} + 4Zn_{(s)} + 7OH^-_{(aq)} + 6H_2O_{(l)}\rightarrow 4Zn(OH)_4^{2-}_{(aq)} + NH_3_{(aq)}[/tex]
Zn exists in 0 oxidation state in [tex]Zn[/tex] and forms [tex]Zn(OH)_4^{2-}[/tex] in which it has +2 oxidation state.
Thus, it is oxidized in the chemical reaction. Thus, Zn is reducing agent and [tex]NO_3^-[/tex] is the oxidizing agent.
In reaction (i);
reducing agent in the following:
(i) 8H+(aq) + [Cr2O7]2-(aq) + 3SO32-(aq) => 2Cr3+(aq) + 3SO42-(aq) + 4H2O(l)
[Cr2O7]2- is the oxidizing agent
SO32- is the reducing agent
In reaction (ii),
ii) NO3-(aq) + 4Zn(s) + 7OH-(aq) + 6H2O(l) => 4Zn(OH)42-(aq) + NH3(aq)
NO3- is the oxidizing agent
Zn is the reducing agent.
Oxidizing agent is a substance which bring about oxidation by being reduced and gaining electrons.
A reducing agent is a substance which bring about reduction by being oxidized and losing electrons.
Learn more about oxidizing and reducing agents:
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