At 25∘C, the dissociation constant of a base BOH is 1.0 × 10−12. The
concentration of Hydroxyl ions in 0.01 M aqueous solution of the base
would be
1.0 × 10−7molL−1
BOH ⇋ B++OH−
Initially,
BOH = C, B+ = 0 and OH− = 0
At Equilibrium
BOH = C − Cα, B+ = Cα and OH− = Cα
Kb = C2α2C(1−α) = Cα2 assuming α<<1; 1 − α ∼ 1
10−12 = 10−2 × α2; α2 = 10−10; α = 10−5
OH− = Cα = 0.01 × 10−5 = 10−7