In: Chemistry
Consider the titration of 50.00 mL of 0.100 M trimethylamine ( (CH3)3N, Kb = 6.25 x 10-5) with 0.100 M HI. Calculate the pH at the initial point.
(CH3)3N + H2O -------------------------> (CH3)3NH+ + OH-
0.100 0 0
0.100 -x x x
Kb = x^2 / 0.1-x
6.25 x 10^-5 =x^2 / 0.1-x
x^2 + 6.25 x 10^-5 x - 6.25 x 10^-6 = 0
x = 2.47 x 10^-3
[OH-] = 2.47 x 10^-3 M
pOH = -log [OH-]
pOH = -log (2.47 x 10^-3)
pOH = 2.61
pH +pOH = 14
pH = 11.39