Question

Determine the pH of each of the following solutions (Ka and Kb values are given in Appendix D in the textbook).

9.9

Answer 1

The solution is as shown below,

The reaction will be,

NH2OH <===> NH2+ + OH-

Thus,

Kb = [NH2 +] [OH -] / [NH2OH]
Let, [OH-] = [NH2+] = x
We have, [NH2OH] 0.099 M

Kb for NH2OH = 1.1 x 10^-8 (From standard data chart)

Feed the values,

1.1 x 10^-8 = (x)(x)/0.099

x = [OH-] = 3.3 x 10^-5 M

Calculate pOH

pOH = -log[OH-]

        = -log(3.3 x 10^-5)

        = 4.48

Calculate pH

pH = 14 - 4.48

      = 9.52

Thus, the pH of 9.9 x 10^-2 M hydroxylamine solution is 9.52.