Why micelles form in water and hydrazine. A reexamination of the origins of hydrophobicity
- Alexandria Univ., Egypt
Micelle formation, a typical ''hydrophobic process'' in water, has been studied in hydrazine. The standard free energies, ..delta..G, for micellization are similar in the two solvents (-9.6 kcal mol/sup -1/ for water and -7.8 kcal mol/sup -1/ for hydrazine for sodium dodecyl sulfate). The corresponding ..delta..H/sup 0/ values (-6.1 and -13.3 kcal mol/sup -1/, respectively) and ..delta..S values (11 and -18 gibbs mol/sup -1/, respectively) are very different. The differences between hydrazine and water are attributed to a large positive increment in both ..delta..H(H/sub 2/O) and ..delta..S(H/sub 2/O) accompanying the transfer of the surfactant hydrocarbon chain out of water. These increments nearly compensate each other and thus make only a small contribution to the free energy in the temperature range 25-45/sup 0/C. This interpretation is bolstered by the almost identical free energy of transfer of a methylene group from water (-0.76 kcal mol/sup -1/) and hydrazine (-0.71 kcal mol/sup -1/) to the micelle. These results suggest that the lipophobic properties of water and hydrazine are very similar and that the unique properties of water do not play a dominant role in the equilibrium properties of this liquid. The critical micelle concentrations (cmc) are reported for sodium, octyl, decyl, and dodecyl sulfates and decyl- and dodecyltrimethylammonium bromide in hydrazine at 25, 35, and 45/sup 0/C. 3 figure, 5 tables.
- OSTI ID:
- 6981161
- Journal Information:
- J. Phys. Chem.; (United States), Vol. 87:22
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
HYDRAZINE
SOLVENT PROPERTIES
MICELLAR SYSTEMS
THERMODYNAMICS
WATER
AMMONIUM COMPLEXES
BROMIDES
COMPARATIVE EVALUATIONS
ENTHALPY
ENTROPY
EQUILIBRIUM
EXPERIMENTAL DATA
FLUORESCENCE SPECTROSCOPY
FREE ENERGY
MEDIUM TEMPERATURE
NMR SPECTRA
PERYLENE
QUANTITATIVE CHEMICAL ANALYSIS
QUANTITY RATIO
SAMPLE PREPARATION
SODIUM CHLORIDES
SODIUM COMPLEXES
STRUCTURAL CHEMICAL ANALYSIS
SULFONATES
SYNTHESIS
TEMPERATURE DEPENDENCE
ALKALI METAL COMPLEXES
ALKALI METAL COMPOUNDS
AROMATICS
BROMINE COMPOUNDS
CHEMICAL ANALYSIS
CHLORIDES
CHLORINE COMPOUNDS
COMPLEXES
CONDENSED AROMATICS
DATA
EMISSION SPECTROSCOPY
ENERGY
HALIDES
HALOGEN COMPOUNDS
HYDROGEN COMPOUNDS
INFORMATION
NITROGEN COMPOUNDS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
SODIUM COMPOUNDS
SPECTRA
SPECTROSCOPY
THERMODYNAMIC PROPERTIES
090310* - Inorganic Hydrogen Compound Fuels- Properties- (1976-1989)
400201 - Chemical & Physicochemical Properties