If the Kb of a weak base is 4.6 * 10-6, what is the pH of a 0.32 M solution of this base?

Assuming that the given base is a weak monoprotic base, the pH of the solution can be calculated as follows:

Write the balanced reaction and ice chart:

BOH - - > OH - + B+

i 0.32 0 0

c - x x x

e 0.32-x x x

Kb = x^2 / (0.32-x)

x = 1.21x10^-3 = [OH-]

pOH = - log[OH-] = - log[1.21x10^-3] = 2.917

pH = 14 - pOH = 14 - 2.917 = 11.08