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  • 1 University of La Coruña Department of Energía y Propulsión Marina ETS Ingenieros de Caminos, Canales y Puertos, Campus de Elviña 15071 La Coruña Spain
  • | 2 University of Santiago de Compostela Nanomaterials and Soft Matter Group, Department of Physics of Condensed Matter, Faculty of Physics Campus Sur s/n 15782 Santiago de Compostela Spain
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Abstract  

The molality dependence of specific conductivity of pentadecyl bromide, cetylpyridinium bromide and cetylpiridinium chloride in aqueous solutions has been studied in the temperature range of 30–45 °C. The critical micelle concentration (cmc) and ionization degree of the micelles, β, were determined directly from the experimental data. Thermal parameters, such as standard Gibbs free energy
\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{upgreek} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} $$\Updelta G_{m}^{0} ,$$ \end{document}
enthalpy
\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{upgreek} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} $$\Updelta H_{m}^{0}$$ \end{document}
and entropy
\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{upgreek} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} $$\Updelta S_{m}^{0} ,$$ \end{document}
of micellization were estimated by assuming that the system conforms to the pseudo-phase separation model. The change in heat capacity on micellization
\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{upgreek} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} $$\Updelta C_{p} ,$$ \end{document}
was estimated from the temperature dependence of
\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{upgreek} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} $$\Updelta H_{m}^{0} .$$ \end{document}
An enthalpy–entropy compensation phenomenon for the studied system has been found.