Question

Give reasons for each of the following: 

1. Bleaching of flowers by Cl₂ is permanent while by SO₂ is temporary. 

2. Molten aluminium bromide is a poor conductor of electricity. 

3. Nitric oxide becomes brown when released in air.

4. PCl₅ is ionic in nature in the solid state. 

5. Ammonia is a good complexing agent.

Answer 1

1. Cl₂ bleaches by oxidation, while SO₂ does it by reduction. The reduced product gets oxidise again and the colour is regained back. 

2. Aluminium bromide exists as a dimer, Al₂Br₆ . In this structure, each aluminium atom forms one coordinate bond by accepting a lone pair of electrons from the bromine atom of another aluminium bromide molecule and thus complete the octet of electrons. Due to lack of free electrons, molten aluminium bromide is a poor conductor of electricity. 

3. Nitric oxide reacts with air and oxidised into NO₂ which is brown in colour. 

2NO + O₂ → 2NO₂ 

4. In solid state PCl₅ exists as [PCl₄]⁺ [PCl₆]^- and hence it is ionic in nature. Due to its ionic nature, it conducts current on fusion. 

5. N atom in ammonia has lone pair of electrons which can coordinate with other atoms or cations required for the stability of electron pair.