Question

Give appropriate reason for each of the following :
(i) Metal fluorides are more ionic than metal chlorides.
(ii) Perchloric acid is stronger than sulphuric acid.
(iii) Addition of chlorine to KI solution gives it a brown colour but excess of Cl₂ makes it colourless.

Answer 1

[Hint : (i) According to Fajan’s Rule, bigger ions are more polarized than the
smaller ions by a particular cation.
(ii) ClO₄ - is more resonance stabilized than SO₄ ²- since dispersal of negative charge is more effective in ClO₄  as compared with SO₄ ^2-.
(iii) 2KI + Cl₂ → 2KCl + I₂
5Cl₂ (excess) + I₂ + 6H₂O → 2HIO3 + 10HCl
(colourless)