In: Chemistry
What is the pH of a 203 mL sample of 3.601 M acetic acid (CH3COOH) (Ka = 1.8 x 10-5)?
CH3COOH -----------------------------> CH3COO- + H+
3.601 0 0 ----------------------> initial
3.601-x x x-------------------------> after dissociation
Ka = [CH3COOH][H+]/[CH3COOH]
Ka = x^2 / 3.601-x
1.8 x 10^-5 = x^2 / 3.601-x
x^2 + 1.8 x 10^-5 x -6.48 x 10^-5 = 0
x = 8.04 x 10^-3
[H+] = 8.04 x 10^-3 M
pH = -log[H+]
pH = -log(8.04 x 10^-3 )
pH = 2.09