Measurement of Vapor Pressures by Means of Matched Thermistors.

Osmotic coefficients and enthalpies of dilution of aqueous sodiumn-alkane-1-sulphonates at the temperatures (298.15, 313.15, 328.15, and 343.15) K

“…All D dil H m values for a given surfactant were treated simultaneously with the mass-action model using equation (8). Thermodynamic self-consistency was assured for the relationships between K, D r H°m, and D r C°p ,m using equations (10) to (12): The values of B 1g (=0) and B ng given in table 4 were used at T = 328.15 K, and the temperature dependence of B 1g was described by equation (13):…”

“…The calorimetric experiments are more difficult to perform and require larger correction terms at the higher temperatures. As noted earlier, (1)(2)(3)24) there are several assumptions inherent in equations (1) to (8). The assumption of a fixed single stoichiometry for reaction (1) is likely to become less valid at the higher temperatures.…”

“…The assumption of a fixed single stoichiometry for reaction (1) is likely to become less valid at the higher temperatures. The inclusion of additional temperature-dependent terms in equations (10) to (13), and the use of the term (1B ng /1T ) p in equation (8), would help to compensate for the breakdown in these assumptions. However, a thermodynamically based model and equations FIGURE 8.…”

“…The vapour-pressure osmometry measurements were made with a Hitachi Perkin-Elmer Model 115 molar mass apparatus maintained at T = (328.15 2 0.1) K. This type of osmometer, its principles of operation, and its application to the estimation of osmotic coefficients of surfactant solutions have been described previously. (8)(9)(10)(11)(12)(13)(14) Details of the experimental procedure, the calculation of osmotic coefficients, and the method of calibration were identical to those described in an earlier study. (14) The calibration constant was determined by making a series of measurements of NaCl(aq) solutions.…”

Vapor Pressures of Aqueous Potassium Octanoate Solutions

“…Vapor pressure depressions of a series of potassium octanoate solutions \\rere measurecl with a pair of thermistors in an apparatus similar to that clescribecl by several previous workers (4)(5)(6). The For personal use only.…”