Anonymous

Do your own homework.

Anonymous

Calculate the pH .... I always have my students do the equilibrium calculations shown by Fern. But in addition, you will also find that the Henderson-Hasselbalch equation will give a good approximation of the pH of a buffer. To justify using the HH equation, I have my students use the equilibrium (ICE) calculations to derive the HH equation. The HH equation makes the same approximation that Fern has done: [acid] - x = [acid] pH = pKa + log([base] / [acid]) pH = -log(1.4x10^-4) + log(0.25M / 0.75M) pH = 3.38

Anonymous

Ka = [H^+][Lactate^-] / [ Lactic Acid] [H+] = Ka[Lactic Acid] / [Lactate&-] [H+] = 1.4x 10^-4 x 0.75 / 0.25 [H+] = 4.2 x 10^-4 Hence pH = -log(10)[H^+] pH = -log(10) [4.2 x 10^-4] pH = -(-3.37675...) pH = 3.38