Question

a) Nitrogen forms a number of oxides in the different oxidation stats. Write the names and structural formulae of any four oxides of nitrogen. 

b) Boiling point of H₂O (373 K) is very much higher than that of H₂S (213k). Give reason.

c) Suggest a method for the quantitative estimation of ozone (O₃).

Answer 1

Name	Structural formula
Nitrous oxide	Nitric oxide
Dinitrogen Oxide (N2O)	N ≡ N - O
Nitrogen Monoxide (NO)	N = O
Dinitrogen Trioxide (N2O3)
Nitrogen Dioxide (NO2)
Dinitrogen Tetroxide (N2O4)

b) Molecules of water are highly associated through hydrogen bonding resulting in its high boiling point. Hydrogen bonding is not possible in H₂S.

c) When O₃ reacts with an excess of Kl solution buffered with a borate buffer (pH = 9.2) 12 is liberated, which can be titrated against a standard solution of sodium thiosulphate. 2Kl+ H₂O + O₃ → O₂ + KOH + l₂