Sodium salts of pectin and of carboxy methyl cellulose in aqueous sodium chloride. II Osmotic pressures

Abstract

Abstract The osmotic pressure of solutions of sodium pectinate and three samples of sodium carboxy methyl cellulose in aqueous solutions of sodium chloride were measured in a Fuoss and Mead osmometer. The primary aim was to obtain the molecular weights of the samples. As a by‐product the change of osmotic pressure with polymer concentration and salt content was studied. The reduced osmotic pressure proves to be a linear functon of the polymer concentration. The slopes of the lines p/c versus c vary with the concentration of the sodium chloride in a manner which is in reasonable agreement with the predictions of the Donnan equilibrium. An accurate check is impossible because the activity coefficients are not known.