1. In the laboratory, a general chemistry student measured the pH of a 0.540 M a
ID: 1041194 • Letter: 1
Question
1. In the laboratory, a general chemistry student measured the pH of a 0.540 M aqueous solution of triethylamine, (C2H5)3N to be 12.239.
Use the information she obtained to determine the Kb for this base.
Kb(experiment) =
2. In the laboratory, a general chemistry student measured the pH of a 0.540 M aqueous solution of aniline, C6H5NH2 to be 9.315.
Use the information she obtained to determine the Kb for this base.
Kb(experiment) =
3. In the laboratory, a general chemistry student measured the pH of a 0.540 M aqueous solution of triethylamine, (C2H5)3N to be 12.209.
Use the information she obtained to determine the Kb for this base.
Kb(experiment) =
Explanation / Answer
1)
(C2H5)3N + H2O ---------------> (C2H5)3NH+ + OH-
pH = 12.239
pOH = 1.761
[OH-] = 0.0173 M
[C] = 0.540
Kb = (0.0173)^2 / 0.540 - 0.0173
Kb = 5.75 x 10^-4
2)
pH = 9.315
pOH = 4.685
[OH-] = 2.065 x 10^-5 M
Kb = (2.065 x 10^-5)^2 / 0.540 - 2.065 x 10^-5
Kb = 7.9 x 10^-10
3)
[OH-] = 0.0162 M
Kb = (0.0162)^2 / 0.540 - 0.0162
Kb = 5.0 x 10^-4
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