Unraveling order and entropy with modern quasi-chemical models

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作   者：

Soares, Rafael de P.;  Staudt, Paula B.; 

作者机构：

Univ Fed Rio Grande do Sul; 

关键词：

Water;  LIQUID-MIXTURES;  Association;  THERMODYNAMICS;  Quasi-chemical;  Polar;  EXCESS GIBBS ENERGY;  EQUILIBRIUM;  LOCAL COMPOSITIONS;  COSMO-RS;  EXPRESSION;  COSMO-SAC; 

期刊名称：

Fluid Phase Equilibria

i s s n：

0378-3812

年卷期：

2024 年 583 卷

页   码：

ARTN 114113-

页   码：

摘   要：

In this work, the derivation of a general expression for the residual entropy for quasi -chemical models - including modern COSMO-RS/SAC - is shown. This expression is equivalent to equations that had to be assumed or postulated in previous works. More interestingly, it allows to unravel order (or non -randomness) in pure compounds and mixtures in a very detailed way. It is possible to investigate the entropic contribution of every possible pair of molecular surface segments, without relying on any lattice or coordination number. Different types of mixtures are very well explained by modern quasi -chemical models, including polar, apolar, and associating compounds showing positive, negative, and s -shaped excess entropy. Finally, it is shown that these models are unable to precisely represent some aqueous mixtures - the assumption of pairwise additive interactions is apparently too limited in those cases.