Direct access to thermodynamics from equilibrium compositional heterogeneities.

Area of Science:

• Thermodynamics
• Physical Chemistry
• Chemical Engineering

Background:

• Traditional thermodynamic analysis requires multiple bulk states to extract information from compositional heterogeneities.
• Accessing thermodynamic properties across a range of local compositions is challenging with conventional methods.

Purpose of the Study:

• To demonstrate that thermodynamic information can be extracted from equilibrium compositional heterogeneities within a single system.
• To develop a method for accessing thermodynamic properties over a broad range of local compositions from a single simulation.

Main Methods:

• Utilizing equilibrium simulations to analyze compositional heterogeneities.
• Applying the derived thermodynamic framework to a specific liquid-liquid system involving water extraction.
• Validating the approach by comparing simulation results with experimental data.

Main Results:

• A single equilibrium simulation is sufficient to recover broad thermodynamic behavior.
• The excess chemical potential of water shows a simple, thermodynamically consistent dependence on local composition.
• The method accurately reproduces experimental data and exhibits predictive power beyond the established range.
• The observed functional dependence is intrinsic, not limited to interfacial environments.

Conclusions:

• Compositional heterogeneities serve as an effective thermodynamic sampling tool.
• This approach provides access to equilibrium distributions and thermodynamic properties without requiring multiple bulk states or explicit correlation functions.
• The method is applicable beyond molecular simulations and can potentially be extended to experimental measurements.