Calculate the concentration of OH of the following solutions

Calculate the concentration of OH- of the following solutions amine. (K_b = 1.00 times 10^-5) (Ans. last three scenarios, [OH] times 10^3: 1.62, 5.21, 10.1)

Solution

3. concentration of [OH-] ion,

amine + H2O <==> amineH+ + OH-

let x amount has hydrolysed in each case

Kb = [amineH+][OH-]/[[amine]

NaOH is strong acid dissociates completely into Na+ and OH- ions.

So,

Component A : 0.100 M amine

1 x 10^-5 = x^2/0.1

x = [OH-] = 1 x 10^-3 M

Component A = 0.1 M amine

component B = 0.001 M NaOH

[OH-] = 0.001 + 0.001 = 0.002 M

Component A = 0.1 M amine

component B = 0.005 M NaOH

[OH-] = 0.001 + 0.005 = 0.006 M

Component A = 0.1 M amine

component B = 0.010 M NaOH

[OH-] = 0.001 + 0.010 = 0.011 M