The free energy of transfer from the continuous oil phase to the interfacial region for 1-octanol in nonionic surfactant (Triton X 100)-water-oil(alkylarom.)-1-octanol microemulsions was reported. The effect of temperature on the change in free energy, entropy, and enthalpy value was studied. Logarithms of the free energy, entropy, and enthalpy values changed as a linear function of the no. of C atoms in the alkylaroms. The data were analyzed with respect to the microemulsion structure and stability.

Key words: WATER, AROMATIC HYDROCARBON, EMULSIONS, THERMODYNAMIC FUNCTION, ENTROPY, ENTHALPY, FREE ENERGY, NON IONIC SURFACTANTS, SIDE CHAIN, CHAIN LENGTH