Compensation relationship in thermodynamics of solvation and vaporization: Features and applications. I. Non-hydrogen-bonded systems

• Published in: Journal of molecular liquids Vol. 368; p. 120762
• Main Authors: Solomonov, Boris N., Yagofarov, Mikhail I.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15-12-2022
• Subjects: Compensation relationship; Solvation enthalpy; Solvation Gibbs energy; Vapor pressure; Vaporization enthalpy; Vaporization Gibbs energy; Solvation Gibbs energy; Compensation relationship; Solvation enthalpy; Vapor pressure; Vaporization enthalpy; Vaporization Gibbs energy
• ISSN: 0167-7322; 1873-3166
• DOI: 10.1016/j.molliq.2022.120762

•Compensation relationship is investigated in non-hydrogen-bonded systems.•Vaporization and solvation parameters obey the same compensation relationship.•Long-chain aliphatic compounds obey linear correlation with lower slope.•Vapor pressure at any temperature can be found from vaporization enthalpy.•Vapor pressure at any temperature and enthalpy can be found from boiling point.
There is a well-known connection between the entropies (or Gibbs energies) and enthalpies of many processes, particularly solvation, called the compensation relationship. It has been recognized for a long time that hydrogen bonding in solvents has a significant effect on the compensation relationship. However, apart from that, little attention has been paid to the features of the correlation between the Gibbs energies and enthalpies of solvation that may manifest different classes of organic non-electrolytes.
In this work we examined whether the Gibbs energies and enthalpies of solvation and vaporization of various non-hydrogen-bonded organic non-electrolytes obeyed the same relationship. It was established that, while most organic non-electrolytes, together with rare gases, follow the common linear correlation, long-chain aliphatics form the separate line with the lower slope.
Root-mean-square deviation of the observed correlations was below 1 kJ·mol−1, which enables to use them as a tool for predicting the Gibbs energies of solvation/vaporization from the enthalpies at 298.15 K and vice versa. Combined with our recent findings, this can be applied to determining the vapor pressure as a function of temperature from the vaporization enthalpy, or a single measurement of the vapor pressure at an arbitrary temperature, or the boiling point under a given pressure.