Solvent isotope effects on the solubility of argon and pair interactions in aqueous solution of hexamethylenetetramine

The solubilities of gaseous argon in solutions of hexamethylenetetramine (h mta) in H2O and D2O were measured at different concentrations, at five temp eratures in the range of 283-318 K. and at a partial gas pressure of 101325 Pa by microvolumetry with an accuracy of less than or equal to 0.3%. The s tandard Setchenov coefficients for argon solutions and the thermodynamic pa rameters of Ar-hmta pairvise interactions wire calculated from the data on the solubility. Interactions between hydrated Ar and hmta molecules are cha racterized by mutual repulsions. The structural states of water in the hydr ation sphere of hmta and in the bulk of solution are substantially differen t. Due to the difference in the mechanisms of hydration of hmta and Ar, the addition of the first component leads to a decrease in the solubility of t he second component.