Question

You have determined that the solubility product Ksp of Herbigon is 8.50

Answer 1

Herbigon is a herbicide used in the agriculture.

XAc + HAc ----> X^- + H⁺ + Ac            (Ac = acetate ion, CH₃COO^-)

ICE Table:

                          XAc   HAc            X             H Ac
initial conc.....................1M .............0............ 0.......... 0
change...........................-x............+0.002.......+x..... x+0.002
final...............................1-x ............0.002....... x...... x+0.002

Now,

K_a = antilog(pK_a) = 10^-4.76 = 1.74x10^-5.


K_a = [H⁺][Ac]/[HAc]

K_a = x(x+0.002)/(1-x)       (assume x<<0.002,1)

1.74 x 10^-5 = x x 0.002

x = 0.0087 M

pH= -log[H⁺]

pH = -log(0.0087) = 2.06