Question

Account for the following:
(a) Chlorine water has both oxidizing and bleaching properties.(b) H3PO2and H3PO3act as as good reducing agents while H3PO4does not.(c) On addition of ozone gas to KI solution, violet vapours are obtained.

Answer 1

(I) chlorine need one more electron to complete its octet,thus it reduces itself and act as an oxidising agent.
When chlorine is added to water, hypochlorous acids form:
Cl2 + H2O -> HOCl + H+ + Cl-
Due to its bleaching action it acts as an disinfectant
(b)H3PO4 is already fully oxidized; it cannot accept another oxygen atom, so cannot reduce something. whereas H3PO2 and H3PO3 can accept two and one oxygen respectively
(c)violet vapours are produced due to evolution of hydrogen gas

Answer 2

Hey !!

a) Chlorine water produces nascent oxygen which is responsible for bleaching action and oxidation.

     Cl₂ + H₂O -----> 2HCl + [O]

b) Both H₃PO₂ and H₃PO₃ have P ---- H bonds, so they act as reducing agent. H₃PO₄, has no P ---- H bond but has O ---- H bonds, so it cannot act as a reducing agent.

c) Ozone gas acts as a strong oxidising agent, so it oxidises iodide ions to iodine.

      2I⁻ (aq) + H₂O (l) + O₃(g) ----> 2OH⁻(aq) + I₂(g) + O₂(g)

Good luck !!