PARTIAL MOLAR VOLUMES FOR ACETONITRILE PLUS WATER

The densities of acetonitrile + water were measured over the whole composition range at 5, 15, 25, 35, and 45-degrees-C. The apparent and partial molar volumes and partial molar expansibilities were evaluated for both components as a function of mole fraction. In the aqueous-rich region, the partial molar volume of acetonitrile increases abruptly with the mole fraction. Only a small minimum of the partial molar volume was observed at very dilute solutions at lower temperatures. although a marked maximum was recognized in the partial molar expansibility curve. The partial molar volume of water vs composition curve, on the other hand, passes through a pronounced minimum in the organic-rich region, that is, In contrast with most alcohols + water.