THz Calorimetry of Electrolyte Solutions Links Water’s H-Bond Network to Macroscopic Properties
Year: 2026
Type: preprint
Abstract: Understanding the macroscopic properties of aqueous electrolyte solutions over their full solubility range requires a detailed microscopic picture of water-ion interactions. We combine THz calorimetry and dimensionality-reduction techniques to demonstrate that two to four spectroscopic markers are sufficient to describe ion-specific variations in mixing entropies and enthalpies, viscosity, and limiting conductivity across 19 electrolytes. Those markers allow us to classify electrolytes as ’strong’ or ’weak’ and report on changes in the water’s H-bond network. As concentration increases, spectroscopic nonlinearities due to ion aggregation appear that, based on a multipole expansion model for activities, are correlated with density changes. For CsI and LiCl, as prototypes of weak and strong electrolytes, respectively, the multipole expansion model accurately describes their conductivities, viscosities, and surface tensions. THz spectroscopy in combination with an activity coefficient model directly correlates macroscopic solution properties with changes in the H-bond network, paving the way towards efficient machine-learning approaches.
Source: ChemRxiv
Language: English
Subfield: Fluid Flow and Transfer Processes
Field: Chemical Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7223027609