112. Solving a chemistry problem

To determine the molar mass of the bovine albumin protein, the osmotic pressures of its solutions were measured in an aqueous medium containing 0.15 mol/L sodium chloride and a phosphate buffer designed to maintain a constant pH. Below are the data of two series of measurements - at pH 7.0 and pH 5.3 (20 °C). Determine the desired molecular weight from them. (Note that pH affects the second virial coefficient, so the two sets of measurements should be considered separately and the resulting molecular weights, if they do not differ significantly, should be averaged).
pH = 7.0 pH = 5.3
s, g/l 16.65 29.14 49.84 55.84 8.69 17.14 26.82 56.08
π, mm Hg Art. 5.16 9.79 19.07 21.97 2.44 4.88 8.24 19.40