The ionization constant or dissociation of a base BOH in water may be represented as:
BOH (aq) <---------> B+ (aq) + OH– (aq)
Therefore the ionization constant of the base, Kb,
Therefore, Kb = [B+] [OH–] / [BOH]
(Concentration of water remains constant)
If c is the number of moles of the base in one litre of the solution and α is the degree of ionization, then the concentrations of each species at equilibrium are:
[B+] = cα
[OH–] = cα
[BOH] = c (1 – α)
Therefore, Kb = (cα) X (cα) / c (1 – α)
But for weak bases, α is very small so that 1 – α ≈ 1
Therefore,
Kb = (cα) 2
α= (Kb / c) 1/2
And
[OH–] = c x (Kb / c) 1/2
[OH–] = (Kb. c) 1/2
Explain the Dissociation of bases in water.
Category: Ionic Equilibria
More Questions
- Discuss the concentration of H+ ions for weak acids.
- What do you mean by common ion effect?
- Derive the hydrogen and hydroxyl ion concentration in aqueous solutions of acids and bases.
- Discuss the ionization of water.
- Discuss the Arrhenius concept of Acids and Bases
- Derive the relationship between Kh, Kw, Ka.
- Compare the strengths of acids and bases.
- Calculate the percent ionization of 0.20 M solution of hydrocyanic acid, HCN. Ka for HCN = 4.9 x 10-10.
- Calculate the concentration of H3O+ ions in a mixture of 0.02 M acetic acid and 0.1 M sodium acetate.
- What do you mean by Hydrolysis?