Answer:
k = 2,04x10⁻⁵
Explanation:
The equilibrium of acetic acid (CH₃COOH) in water is:
CH₃COOH ⇄ CH₃COO⁻ + H⁺.
And the equilibrium constant is defined as:
k = [CH₃COO⁻] [H⁺] / [CH₃COOH] (1)
The equiibrium concentration of each specie if the solution of acetic acid is 0,05M is:
[CH₃COOH] = 0,05M - x
[CH₃COO⁻] = x
[H⁺] = x
-Where x is the degree of reaction progress-
As the pH is 3, [H⁺] = 1x10⁻³M. That means x = 1x10⁻³M
Replacing in (1):
k = (1x10⁻³)² / 0,05 - 1x10⁻³
k = 1x10⁻⁶ / 0,049
k = 2,04x10⁻⁵
I hope it helps!
