The solubility of inert gases and methane in H2O and D2O has been measured between room temperature and 600 K. The calculation of Henry’s constants kH, from the solubility data is analyzed in detail; if due account is taken of the nonideality in the gas phase, they can be determined unambiguously up to 520 K. Above this temperature, the ambiguity in kH increases sharply as contributions of third and higher order virial coefficients to the equation of state of the gaseous mixture become more important. The differences of gas solubilities in light and heavy water essentially disappear above the temperature of minimum solubility of the gases. The characteristic thermodynamic features of the aqueous solutions of gases (i.e., large values of −ΔS02 and of ΔC0p2) are still present at 520 K. It is shown that mean-field theories can account for the

We have developed correlations for the Henry's constant k H and the vapor-liquid distribution constant K D for 14 solutes in H 2 O and seven solutes in D 2 O. The solutes considered are common gases that might be encountered in geochemistry or the power industry. Solubility data from the literature were critically assessed and reduced to the appropriate thermodynamic quantities, making use of corrections for nonideality in the vapor and liquid phases as best they could be computed. While the correlations presented here cover the entire range of temperatures from near the freezing point of the solvent to high temperatures approaching its critical point, the main emphasis is on representation of the high-temperature behavior, making use of asymptotic relationships that constrain the temperature dependence of k H and K D near the critical point of the solvent.

The solvatochromism and thermochromism of 4-aminophthalimide and 4-amino-N-methylphthalimide were studied by absorption and steady state and time-resolved fluorescence emission in solvent mixtures of toluene−ethanol and toluene−acetonitrile in the temperature range 5−70 °C. The wavelengths of the maximum of absorption and of fluorescence emission shift to the red with the increase of the proportion of the polar component in the mixture. The greater affinity for the polar component of the mixture of the excited state compared to the ground state enhances preferential solvation, which is the origin of this red shift. On the other hand, a spectral shift to the blue is found upon temperature increase in solvent mixtures. This fact can be explained by considering that association of the polar component with the excited-state solute is exothermic and decreases with temperature. The appointed solvation change is attained by diffusion-controlled exchange of solvent molecules between the bulk and the solvation sphere. This process leads to a time-dependent emission spectrum in the nanosecond time domain. In this work a kinetic scheme is developed to describe this exchange and explain the time-dependent fluorescence emission spectra. The description is based on a Langmuir type association of the solvent molecules with the solute. The solvation equilibrium is attained by stepwise solvent exchange. The kinetic data and the spectral information are integrated in a thermodynamic cycle that can describe the solvation of excited and ground states at any solvent composition.