Solute-induced effects in solvation thermodynamics: does urea behave as a structure-making or structure-breaking solute?

ABSTRACT

We determined the solute-induced perturbation of the water environment around aqueous urea from a microscopic-to-macroscopic formalism, according to a novel approach for the unambiguous interpretation of the structure-making/breaking process, regardless of either the species type or the nature of the solute-solvent interactions. Then, by using experimental data from the available literature, we analysed the evolution of the water structure around urea, assessed the microstructural responses to small perturbations of state conditions including composition, and exploited the formalism to extract three related types of osmotic second virial coefficients. Finally, after discussing the implications of the findings, we answered the question highlighted in the subtitle of this manuscript.

GRAPHICAL ABSTRACT

KEYWORDS:

• Structure making/breaking solutes
• solvation formalism
• Kirkwood-Buff
• osmotic 2nd. viral coefficients
• mixture non-idealities

Acknowledgements

The authors express their gratitude to Prof. Pablo Chialvo for his critical reading of an early version of the manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Ariel A. Chialvo http://orcid.org/0000-0002-6091-4563