Thermodynamics of Micellar Systems: Volumes and Heat Capacities of Alkyldimethylamine Oxides in Water
As part of a general study of the thermodynamic properties of micellar systems, the apparent molal volumes and heat capacities of the homologous alkyldimethylamine oxides, CxDAO, where x = 4,6,8 and 10, were measured with a flow densimeter and a flow microcalorimeter. A wide temperature range was covered with C8DA0, C6DA0 was studied at 25 and 5°C and C4DAO and C10DAO at 25°C only. The changes in volume and heat capacity during micellization are reported. The present data are compared with those of ionic surfactants and organic-aqueous mixed solvents. As with many other hydrophobic solutes which have strong acid-base interactions with water, the apparent and partial molal heat capacities of C8DAO and C10DAO pass through a sharp maximum region and then level off to a constant value.
KeywordsHeat Capacity Ionic Surfactant Micellar System Critical Micelle Concentration Apparent Molal Volume
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