2007-10-30 07:31:14 · 2 answers · asked by buttercrunch 1 in Science & Mathematics ➔ Chemistry
Let pyridine be called Py; let C5H5NH+ be called PyH+
Py + H2O <===> PyH+ + OH-
Kb = [PyH+][OH-] / [Py]
[H2O] = 1.0 by convention. [PyH+] = [OH-] = x. [Py] = 0.250 - x, which is essentially 0.250, because x is so small.
Kb = 1.7 x 10^-9 = x^2/0.250
x^2 = 4.25 x 10^-8
[PyH+] = x = 2.06 x 10^-4 M
2007-10-30 07:41:22 · answer #1 · answered by steve_geo1 7 · 1⤊ 0⤋
C5H5N + H2O = C5H5NH+ + OH-
We know that the concentration of C5H5N is .25M, so let "x" equal the concentrations of C5H5NH+ and OH-.
Kb = [C5H5NH+] [OH-] / [C5H5N] = 1.7 Exp -9
So x^ / .250 = 1.7 Exp -9
x = [C5H5NH+] =[OH-] = 2.1 Exp -5 (only 2 significant figures since your Kb only had 2)
2007-10-30 08:17:33 · answer #2 · answered by Dennis M 6 · 0⤊ 0⤋