Heat capacities and volumes of alkyldimethylphosphine and arsine oxides in water at 25°C

Comparison of the Calorimetric and van't Hoff Enthalpy of Micelle Formation for a Nonionic Surfactant in H2O and D2O Solutions from 15 to 40 °C

“…It may also be pointed out that our earlier value obtained from continuous enthalpy titrations in H 2 O at four temperatures 19 is within experimental error of the result from Method 4 (with no allowance for a possible temperature variation of Δ C p ° in either case). The value obtained from direct heat capacity measurements was slightly lower than our current calorimetric values.…”

A Calorimetric Determination of the Standard Enthalpy and Heat Capacity Changes that Accompany Micelle Formation for Four Long Chain Alkyldimethylphosphine Oxides in H2O and D2O Solution from 15 to 79 °C

“…Finally, the current values of ΔCp° in water for C 8 DPO and C 10 DPO obtained by titration calorimetry (−77 ± 3 and −123 ± 2 cal/(mol·K)) may be compared with corresponding values from direct measurements of the apparent molar heat capacity 16 of −110 to −117 and −115 to −129 cal/(mol·K) depending upon the model used for extrapolation of the data to the cmc and the value of −133 ± 16 for C 10 DPO from continuous titration calorimetry . The importance of the procedure used to obtain thermodynamic values for the micellization process from calorimetric data can be appreciated by comparing the enthalpy change of 8 ± 1 kJ/mol reported by Perron et al for C 6 DPO and an extrapolated value of 15 kJ/mol from the work of Clint and Walker. This apparent discrepancy results from the manner by which the data were treated rather than to differences in the measured values themselves.…”

A styrylpyridinium salt in aqueous solution: unusual solution behaviour

“…Such a change of slope at the c.m.c. of a surfactant has been reported by Perron et al 15 Values for the Rayleigh scattering at an angle of 90°, measured at a temperature of 25 °C, as function of concentration, are shown in Fig. 3; the sharp increase in scattering which occurs at concentrations approaching 0.04 m indicates the appearance of larger particles, the micelles in fact.…”

“…Heats of dilution measurements, at 25 °C, as a function of the initial concentration of the solution, Fig. 3, also show a sharp change of slope, in this case at 0.035 m, yet again indicating a major change in the solution state of the solute, from monomer to micelle 15 has occurred.…”