Question

Question 8.8 While sulphur dioxide and hydrogen peroxide can act as oxidising as well as reducing agents in their reactions, ozone and nitric acid act only as oxidants. Why?

Class XI Redox Reactions Page 272

Answer 1

in SO2, S in +4 oxidation state.we know, minimum O.N of S is -2 and maximum O.N of S is +6. It means O.N of S in SO2 can either decreases or increases its oxidation number.so,SO2 can act both as oxidizing as well as reducing agent.

in H2O2, O.N of O is -1. But we know, minimum O.N of O is -2 and maximum O.N is +2. therefore O in H2O2 can either decreases or increases its oxidation number.so,H2O2 can act both as oxidizing as well as reducing agent.

in O3, O.N of O is zero.it can't increases its oxidation number,it can only decreases its oxidation number from zero to -1 or -2.so,ozone can act only as oxidizing agent.

In HNO3, the oxidation number of N is +5. It is maximum.so,N in HNO3 can only decreases its oxidation number.so,it can act as an oxidizing agent only .

Answer 2

Answer:

Also 4th point added here in HNO3, O.N. of N is5 which is maximum. Therefore, it can only decreases its O. N. And hence it acts as an oxidant only