Q.27 (a) Distinguish between crystalline and amorphous solids.
(b) Explain bleaching action of chlorine in the presence of moisture.
Best answer
Answer:
(a)
| Crystalline solids | Amorphous solids |
|---|---|
| Constituent particles are arranged in a regular, long-range order. | Particles have only short-range order (irregular arrangement). |
| Have a definite geometrical shape. | Have irregular shape. |
| Have a sharp melting point. | Soften over a range of temperature. |
| Anisotropic (properties differ in different directions). | Isotropic (properties same in all directions). |
| Give clean cleavage with plane surfaces on cutting. | Give irregular cleavage. |
| True solids, e.g. NaCl, diamond, quartz. | Pseudo solids or supercooled liquids, e.g. glass, rubber, plastics. |
(b) Bleaching action of chlorine: In the presence of moisture, chlorine reacts with water to give nascent oxygen:
Cl2 + H2O → HCl + HOCl; HOCl → HCl + [O]
The nascent oxygen oxidises the coloured substance to a colourless product: coloured substance + [O] → colourless substance. Thus bleaching by chlorine is due to oxidation and is permanent. Dry chlorine does not bleach. It is used to bleach wood pulp, cotton and textiles, but not delicate articles like silk and wool, which it damages.
Log in or create a free account to answer this question.
