CRYOSCOPIC BEHAVIOR IN THE BINARY-MIXTURES OF ACETAMIDE-SODIUM ACETATE AND ACETAMIDE-SODIUM ACETATE TRIHYDRATE

The melting point depression of acetamide on addition of anhydrous sod ium acetate and sodium acetate trihydrate was followed by DSC. Two set s of measurements were made for two crystalline forms in which the mel ts crystallized. From cryoscopic data, activity coefficients of acetam ide were calculated in the concentration range 0 to 0.390 mole fractio n of sodium acetate and 0 to 0.376 mole fraction of sodium acetate tri hydrate. Activities of the salt components were calculated from the ac tivities of the solvent using a simple analytical method. From melting point depression data and the known molar cryoscopic constant of acet amide, the Van't Hoff dissociation factor was calculated for both anhy drous and hydrated sodium acetate in the concentration ranges studied.