Question

Part A

Calculate the pH in 1.00MCH3CO2H.

Part B

Calculate the concentrations of all species present (H3O+, CH3CO2?, CH3CO2H, and OH?) in 1.00M CH3CO2H.

Answer 1

CH3COOH -------------> CH3COO- + H+

   1                                  0                  0

   1-x                                x                 x

Ka= [CH3COO-][H+]/[CH3COOH]

    Ka = x^2/1-x

ka for CH3COOH = 1.8 x10^-5

1.8 x10^-5 = x^2/1-x

x= 4.23 x 10^-3

x= [H+]= [CH3COO-] = 4.23 x 10^-3M

[CH3COOH] = 1-x = 0.995M

Part A

pH= -log[H+]= -log(4.23 x 10^-3)

      pH= 2.37

Part B

[H+]= 4.23 x 10^-3M

[CH3COO-] = 4.23 x 10^-3M

[CH3COOH]   = 0.995M

[OH-] = Kw/[H+] = 10^-14/4.23 x 10^-3

[OH-]   = 2.364 x10^-12M