Strength of acids and base interm of Ka, Kb and pKa and pKb values

Problems

2. Which of the following acids is the strongest and which one is the weakest. Explain.

Solution

Thus, larger the K_a value stronger is the acid. Therefore,

3. Calculate the degree of ionization and [H₃O⁺] of a 0.1 mol /L solution of acetic acid. Given: K_a(CH₃COOH) = 1.8 x 10^-5 mol / L.

Solution

Let 'a' be the degree of ionization. The concentration of various species involved in the equilibrium are as follows:

The equilibrium constant for the ionization of CH₃COOH can be written as follows:

CH₃COOH is very feebly ionized. So, 'a' may be ignored in comparison to 1. Then,

4. At 298 K, a 0.1 M solution of acetic acid is 1.34% ionized. What is the ionization constant (K_a) for the acid?

Solution

Acetic acid ionizes as follows: