Question

Hydrazine (NH2NH2) is a weak base that ionizes in water as follows.

NH2NH2(aq) + H2O(l) <==> HNH2NH2^+(aq) + OH^−(aq)

Calculate the concentration of OH^− ions in a 0.20 M solution of hydrazine, given that the base-dissociation constant (Kb) for hydrazine is 1.3 ✕ 10^−6. (Note that 0.20 M is known as the initial, formal, or total concentration of hydrazin.)

Answer 1

hydrazine = BH
......BH + H2O ==> BH2^+ + OH^-
I....0.2M...........0.......0
C.....-x............x.......x
E....0.2-x..........x.......x

Write the Kb expression, plug in the E line and solve for x = OH^-

Post your work if you get stuck.

Answer 2

5.7 x 10-12