PARTIAL MOLAL VOLUMES AND COMPRESSIBILITIES OF NORMAL-ALCOHOLS IN MICELLAR SOLUTIONS OF SODIUM ALKYLCARBOXYLATES

The partial molal volumes of n-alcohols (C3C10) in micellar solutions of sodium dodecanoate, sodium decanoate, and sodium octanoate have been determined at 25°C by density measurements. From ultrasound measurements the partial molal compressibilities of the alcohols in the micellar solutions have been determined. The partial molal volumes and compressibilities of the alcohols in micellar solutions are higher than those in water and are similar to the partial molal quantities for the liquid alcohol. The partial molal volumes and compressibilities decrease with increasing chain length of the surfactant and with increasing surfactant concentration. The same trend has been found for the corresponding quantities for liquid alcohols, and the results have been interpreted by comparing the interior of the micelles to liquid alcohols. © 1979.