Thermodynamics of Partitioning System with Dimerization Taking Place in Both Phases
Bibliographic record
Abstract
The partition coefficients of benzoic acid in partially miscible two phase mixtures of (methanol + cyclohexane) were measured at the temperature of 293.15, 303.15, and 313.15 K. The experimental results show that the benzoic acid is more soluble in methanol than in cyclohexane and thus it makes the partition coefficients, defined as the ratio of the total molar concentration of benzoic acid in methanol phase to cyclohexane phase, be greater than unity. In addition, the partition coefficient at each temperature is not a constant but increases with the increase of benzoic acid concentration in each phase even at very low concentration. This seeming deviation to the Nernst law can be explained by chemical theory of strong dimerization reactions taking place in both phases. Accordingly, a new generalized equilibrium model was proposed to describe the partition system with solute self-dimerization in both phases. The new model predictions agree well with the experimental data and the equilibrium constants for all the proposed association and partition reactions are obtained simultaneously by fitting the experimental data with nonlinear least-squares method. The results show that there is much stronger dimerization reaction for benzoic acid in methanol phase than in cycolhexane phase, which results in that the dimerization in cycolhexane phases can be totally neglected. In the methanol phase alone, the calculation results further show that dimerization of benzoic acid is so strong that almost all the solute molecules form dimers within the concentration investigated. The standard thermodynamics functions of Gibbs energy, enthalpy and entropy changes for the proposed reactions were estimated with the obtained parameters at different temperature.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".