Question

Calculate the concentration of the lactate ion in a solution that is 0.100 mm in lactic acid ( ch3ch(oh)coohch3ch(oh)cooh , pkapka = 3.86) and 0.080 mm in hclhcl .

Answer 1

Lactic acid ⇒ H+ + Lactate
pKa = 3.86

Ka = 1.38 x 10^-4 would be equal to [H+] [lactate] / [lactic acid]

HCl ⇒ H+ + Cl-
[H+] = 0.08

Lactic acid = 0.10 M

1.38 x10^-4 would be equal to 0.08 [Lactate] / 0.10

Lactate = 0.10(1.38 x 10^-4/ 0.08
Lactate = 1.73 x 10^-4