calculate the ph of a buffer system containing 1.0 m ch3cooh and 0.50 m ch3coona. (ka of acetic acid, CH3COOH is 1.8x10^-5)

Answer 1

Hi Ashley...

I think the m in 1.0 m should actually be M (molar) not molal. Same for the other concentration.

To find the pH of a buffer, it's usually easiest to just use the Henderson Hasselbalch equation:

pH = pKa + log [salt]/[acid]

pKa = -log Ka = -log 1.8x10-5 = 4.74

pH = 4.74 + log (0.50 M/1.0 M) = 4.74 + log 0.5 = 4.74 + (-0.3)

pH = 4.74 - 0.3

pH = 4.44