Question

What are the criteria for purity of a solid?​

Answer 1

Answer:

• i. A chemically pure compound' has characteristic physical properties such as crystalline for refractive index, specific gravity, density, sharp melting and boiling point etc.
• ii. The magnitude of these properties change depending upon the nature and the amount of impurities present.
• iii. Presence of impurities lowers the melting point of solids and increases the boiling point of liquid.
• iv. Thus, melting point of a solid and boiling point of a liquid are important criteria of purity.

Answer 2

Answer:

• Melting point is used as criteria for purity of solids.
• Pure solids will have sharp and fixed melting point. For example, pure NaCl always melts at 801 ℃.
• Impure solids have lower and variable melting point due to presence of impurity. For example, adulterated NaCl will have variable low melting point.