Question

The next 11 questions are related to the titration of 40.00 mL of a 0.0900 M acetic acid solution with 0.0700 M KOH. Assume that the temperature is 25 oC. What is the initial pH of the analyte solution?

Answer 1

Answer:

2.9 is the initial pH of the analyte solution.

Explanation:

The dissociation constant of acetic acid as per theoretical value =  $K_a$

$K_a=10^{-4.756}=1.8\times 10^{-5}$

The initial concentration of acetic acid = c = 0.0900 M

$HAc\rightleftharpoons Ac^-+H^+$

initially

c       0    0

At equilibrium

(c-x)      x  x

The expression of dissociation constant :

$K_a=\frac{[Ac^-][H^+]}{[HAc]}$

$1.8\times 10^{-5}=\frac{x\times x}{(c-x)}$

$1.8\times 10^{-5}=\frac{x\times x}{(0.0900-x)}$

Solving for x:

x = 0.001264 M

$[H^+]=0.001264 M$

The pH of the solution :

$pH=-\log[0.001264]=2.898\approx 2.9$

2.9 is the initial pH of the analyte solution.