Thermodynamic characterization of
micelle formation from an ionic
surfactant in aqueous solutions is a classic experiment in physical
chemistry. The critical micelle concentration (CMC) and the degree
of micelle ionization (α) can be directly obtained by conductimetry,
then thermodynamic parameters (ΔG
m
o, ΔH
m
o, ΔS
m
o) are deduced from the CMC values at different
temperatures. Herein, the CMC values at different temperatures were
generated by multiple student groups, and the resulting errors were
combined with the enthalpy calculation error for micelle formation
(ΔH
m
o). Under the presented model it was found that
ΔH
m
o data were very difficult to obtain using the
conductivity method. The isothermal titration microcalorimetry (ITC)
method gave a direct ΔH
m
o value, which was incorporated
into the experiment to determine the accuracy of the surveyed data.
The introduction, design, and improvement of a “thermodynamics
of 1-tetradecyl-3-methylimidazolium bromide (C14mimBr)
micellization” experiment using conductivity and ITC methods
were proposed, which may also improve students’ experimental
ability, practical skills, and quality of research.