Chemical Equilibrium Approach Research Articles

Thermodynamic Evaluation of the Polydispersity of Droplet Microemulsions

By exploiting our previously presented multiple chemical equilibrium approach to the theory of Winsor II microemulsions (Eriksson, J. C.; Ljunggren, S. Progr. Colloid Polym. Sci. 1990, 81, 41.) we derive relations which enable an evaluation from thermodynamic data of the polydispersity of Winsor II type microemulsions as well as of corresponding one-phase (ternary droplet) microemulsions. We find that, quite generally, a size polydispersity ( R /R max ) in the range 0.1-0.2 is to be anticipated for such microemulsion and, moreover, that the absolute width of the size distribution to a large extent is determined simply by the value of the interfacial tensio, γ∞, of the planar, surfactant-laden oil/water interface. The shape and surfactant film packing density flucuations also influence the peak width but to a lesser extent. Furthermore, we show how the curvature-related bending constant k 2 =2k c +k c can be evaluated from the overall volume fraction of droplets

Formation of nitric acid hydrates ‐ A chemical equilibrium approach

Published data are used to calculate equilibrium constants for the reactions over the temperature range 190 to 205 K. Standard enthalpies of formation and standard entropies are calculated for the tri‐ and mono‐hydrates. These are shown to be in reasonable agreement with earlier calorimetric measurements. The formation of nitric acid trihydrate in the polar stratosphere is discussed in terms of these equilibrium constants.