Question

1. Explain why sodium chloride:

(a) does not conduct electricity when solid, but does when molten

(b) has a high melting temperature

(c) is soluble in water.

Answer 1

a. Sodium chloride is ionic solid but in pure solid or crystal does not conduct electricity as current conducted by free Na+ and Cl- but in solid Na+ and Cl- are strongly attracted with each other and that's why they are not free to carry electricity. But in moten or liquid NaCl has free Na+ and Cl- so it can conduct electricity.

b. As NaCl is ionic solid due to strong electrostatic attraction among Na+ and Cl- ion it has high melting point.

c. As NaCl is ionic solid and water is highly polar solvent it can easily solvate the Na+ and Cl- by breaking the attraction among Na+ and Cl- in crystal. So this way water dissolves NaCl.