The reaction for the base can be written as BOH + HCl → BCl + H2O B++H2O ⇌ BOH + H+ Initial concentration : c → 0 , 0 Equilibrium concentration : c - cα → cα , cα Volume of HCl used can be obtained as M1V1(BOH) = M2V2(HCl)
2
5
×2.5 =
2
15
×V2 V2 = 7.5 ml Similarly, concentration of salt can be obtained as M1V1(salt) = M2V2(BOH) M1 × (2.5 + 7.5) = 2.5 ×
2
5
M1 = 0.1 M We know that Ka×Kb = Kw Ka =
cα2
(1−α)
=
Kw
Kb
. Solving, we get a = 0.27. [H+] = cα = 2.7 × 10−2 M