we will use the PH formula: PH = Pka + ㏒ [salt/acid] PH= Pka +㏒ [lactate/lactic] when Pka = -㏒Ka = -㏒ 1.37x10^-4 = 3.86 and we have PH =4.12 So by substitution: 4.12 = 3.86 + ㏒[actate/lactic] ∴[actate/lactic] = 1.82 ∴[lactic/actate] = 1 / 1.82 = 0.55
