Improved evaluation of liquid densities using van der Waals molecular models

Area of Science:

• Physical Chemistry
• Computational Chemistry
• Chemical Engineering

Background:

• Estimating liquid molar volumes and densities is crucial for chemical process design and understanding molecular interactions.
• Existing methods like group contribution and quantitative structure-property relationships (QSPR) have limitations in parameterization and reliability.
• The van der Waals model provides a theoretical basis for molecular interactions but requires accurate parameterization for volume and density predictions.

Purpose of the Study:

• To develop a new, parameter-efficient approach for estimating molar volumes and densities of liquids.
• To leverage the correlation between intermolecular volume and atomic contributions to molecular surface area.
• To quantify the influence of hydrogen bonding on these properties.

Main Methods:

• Utilizing van der Waals models combined with atomic contributions to molecular surface area.
• Developing a novel correlation between intermolecular volume and surface area contributions.
• Applying the method to various H-C-N-O-F-S-Cl-Br compounds under ambient conditions.

Main Results:

• The developed method accurately estimates molar volumes and densities, showing remarkable agreement with the ACD group contribution method.
• The approach requires significantly fewer empirical parameters compared to traditional methods.
• It provides a quantifiable measure of hydrogen bond contributions and demonstrates higher reliability than QSPR.
• The method offers a natural pathway for incorporating temperature effects, unlike existing group contribution methods.

Conclusions:

• The new approach offers a reliable and parameter-efficient method for predicting liquid densities and molar volumes.
• It provides a valuable tool for chemical property estimation, particularly for compounds with varying functional groups and hydrogen bonding capabilities.
• This method advances the application of van der Waals models in predictive chemistry and chemical engineering.