Question

Explain about the strength of acids on the basis of K_a value.

Answer 1

1. K_a is called the ionisation constant or dissociation constant of the acid. It measures the strength of an acid.

2. Acids such as HCI, HNO₃ are almost completely? onised and hence they have high K_a value i.e., K_a for HCI at 25°C is 2 x 10⁶.

3. Acids such as formic acid and acetic acid are partially ionised in solution and have low K_a value. i.e., K_a for acetic acid 1.8 x 10^-5 at 25°C

4. Acids with K_a value greater than ten are considered as strong acids and less than one considered as weak acids.