Question

While sulphur dioxide and hydrogen peroxide can act as oxidizing as well as reducing agents in their reaction, ozone and nitric acid act only as oxidants. Why?

Answer 1

Hint:Oxidizing agents itself get reduced. Reducing agents itself gets oxidized. Oxidation means increase in oxidation no. while reduction means reduce in oxidation no.

Complete step-by-step answer:
In \[S{O_2}\], the oxidation no of \[S\] is +4 and the range of O.N. that \[S\] can have is from +6 to -2 therefore, \[S{O_2}\] can act as an oxidizing as well as reducing agent.
In \[{H_2}{O_2}\], the O.N. that \[O\] is -1 and the range of the O.N. that \[O\] can have is from \[O\] to -2 Hence, \[{H_2}{O_2}\] can act as oxidizing as well as reducing agent.
In ozone, the O.N. of \[O\] is zero and the range of O.N. that \[O\] can have is from 0 to -2 therefore, O.N. can only decrease, Hence, \[O\] acts as an oxidant.
In \[HN{O_3}\], the O.N. of \[N\] is +5 and range of O.N. that \[N\] can have is from +5 to -3, therefore the O.N. of \[N\] can only decrease in this case Hence, \[HN{O_3}\] acts only as oxidant.

Additional information : Oxidizing agents have the ability to oxidize other substances, in other words to accept their electrons, common oxidizing agents are oxygen, hydrogen, peroxide and the halogens.
An oxidizing agent is a chemical species that undergoes a chemical reaction in which it gains one or more electrons in that sense it is one component in the oxidation-reduction reaction.
A reducing agent is an element or compound that loses an electron to an electron recipient in a redox chemical reaction. A reducing agent is thus oxidized when it loses electrons in the redox reaction reducing agent reduces oxidizing agents oxidize oxidizes.

Note:Oxygen can sometimes also attain the oxidation numbers +1 to +2.The abbreviation O.N. refers to oxidation number.