PLEASE SHOW ALL WORK. I DID THIS QUESTION MULTIPLE TIMES, AND I DONT KNOW WHAT I

Question

PLEASE SHOW ALL WORK. I DID THIS QUESTION MULTIPLE TIMES, AND I DONT KNOW WHAT I DID WRONG.

The following information is given. Concentration of sodium acetate: 1.071M   Concentration of Acetic Acid is: 1.041M   The pKa of acetic acid is 4.75.

a) Calculate the pH of the stock acetic solution.

b) Calculate the pH of the stock sodium acetate solution.

The above values are called theoritical values. The values recorded within the experiment using pH meter was pH of stock acetic acid = 2.35 and ph of sodium acetate is 8.38.

Thanks

Explanation / Answer

pKa = 4.74

a)

HA <-> H+ and A-

Ka = [H+][A-]/[HA]

Ka = 10^-4.75

[H+]= x= [A-]

[HA] = M-x = 1.041-x

10^-4.75 = (x*x)/(1.041-x)

x = h+ = 0.0043

pH = -log(H) = -log(0.0043) = 2.36653

b)

for the conjugate

A- + H2O <-> HA + OH-

Kb = [HA][OH-]/[A-]

Kb = Kw/Ka = 10^(14-4.75) = 5.55*10^-10

[HA]= [OH-]= x

[A-] = 1.071 -x

Kb = [HA][OH-]/[A-]

5.55*10^-10 = (x*x)/(1.071 -x)

x =) OH = 2.43*10^-5

pO H= -log( 2.43*10^-5) = 4.6143

pH = 14-4.6143 = 9.3857

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