Question

Which substance is the reducing agent in this reaction? 2KMnO4+3Na2SO3+H2O→2MnO2+3Na2SO4+2KOH

Answer 1

Reducing agent:
`Na_2SO_3`

Step-by-step explanation:

Reducing species is a chemical species which itself undergoes oxidation and reduces other chemical species in a redox reaction.

`2KMnO_4\ + \ 3Na_2SO_3 + H_2O \rightarrow 2MnO_2 + 3Na_2SO_4+2KOH`

Oxidation state of each element is:

Before the reaction After the reaction

`KMnO_4`
`MnO_2`

Oxidation state of K = +1 Oxidation state of Mn = +4

Oxidation state of Mn = +7 Oxidation state of O = -2

Oxidation state of O = -2

Before the reaction After the reaction

`Na_2SO_3`
`Na_2SO_4`

Oxidation state of Na = +1 Oxidation state of Na = +1

Oxidation state of S = +4 Oxidation state of S = +6

Oxidation state of O = -2 Oxidation state of O = -2

Only oxidation states of S and Mn are changes during the reaction.

Oxidation of Mn is decreased and oxidation number of S is increased during the reaction. Hence,
`Na_2SO_3` undergoes oxidation, so acts as reducing agent.