Question

Identify the oxidizing agent and the reducing agent in the following:

Answer 1

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 :-

$8H^+_{(aq)} + [Cr_2O_7]^{2-}_{(aq)} + 3SO_3^{2-}_{(aq)}\rightarrow 2Cr^{3+}_{(aq)} + 3SO_4^{2-}_{(aq)} + 4H_2O_{(l)}$

Cr exists in +6 oxidation state in $[Cr_2O_7]^{2-}$ and forms $Cr^{3+}$ in which it has +3 oxidation state.

Thus, it is reduced in the chemical reaction. Thus, $[Cr_2O_7]^{2-}$ is oxidizing agent and $SO_3^{2-}$ is the reducing agent.

(b) In the given reaction :-

$NO_3^-_{(aq)} + 4Zn_{(s)} + 7OH^-_{(aq)} + 6H_2O_{(l)}\rightarrow 4Zn(OH)_4^{2-}_{(aq)} + NH_3_{(aq)}$

Zn exists in 0 oxidation state in $Zn$ and forms $Zn(OH)_4^{2-}$ in which it has +2 oxidation state.

Thus, it is oxidized in the chemical reaction. Thus, Zn is reducing agent and $NO_3^-$ is the oxidizing agent.