Question

Morpholine (C4H9NO) is a weak organic base with pKb=5.68.

Calculate the pH in a 1.10×10⁻²M morpholine solution.

Calculate the the concentration of C4H9NO in a 1.10×10⁻²M morpholine solution.

Calculate the the concentration of HC4H9NO+ in a 1.10×10⁻²M morpholine solution.

Calculate the concentration of H3O+ in a 1.10×10⁻²M morpholine solution.

Calculate the concentration of OH− in a 1.10×10⁻²M morpholine solution.

Please show work thank you!

Answer 1

pKb = 5.68

Kb = 2.089 x 10^-6

C4H9NO + H2O ---------------------->   HC4H9NO+ +   OH-

0.011                                                               0               0

0.011-x                                                            x                x

Kb = x^2 / 0.011 - x

2.089 x 10^-6 = x^2 / 0.011 - x

x = 1.506 x 10^-4

[OH-] = 1.51 x 10^-4 M

[ HC4H9NO+] = 1.51 x 10^-4 M

[C4H9NO] = 0.0108 M

[H3O+] = 6.61 x 10^-11 M

pOH = -log [OH-] = -log (1.506 x 10^-4)

        = 3.82

pH = 10.18