Thermodynamics of Sodium Dodecyl Sulfate (SDS) Micellization: An Undergraduate Laboratory Experiment
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Juan P. Marcolongo [1] ; Martín Mirenda [1]
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[1] Universidad de Buenos Aires
Universidad de Buenos Aires
Argentina
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- Localización: Journal of chemical education, ISSN 0021-9584, Vol. 88, Nº 5, 2011, págs. 629-633
- Idioma: inglés
- Texto completo no disponible (Saber más ...)
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Resumen
An undergraduate laboratory experiment is presented that allows a thermodynamic characterization of micelle formation of sodium dodecyl sulfate (SDS) in aqueous solutions. The critical micelle concentration (CMC) and the degree of micelle ionization (α) are obtained at different temperatures by conductimetry. The molar standard free energy (ΔmicG̅), enthalpy (ΔmicH̅°), and entropy (ΔmicS̅°) for the micellization process are calculated using the CMC, α, and their temperature dependences within the framework of a simplified model, the closed association model, which assumes an equilibrium between free surfactant monomers and monodispersed micelles. On the basis of hydration phenomena of surfactant molecules, a physicochemical discussion of the results is also proposed.
