Size and temperature dependence of hydrocarbon solubility in concentrated aqueous solutions of urea and guanidine hydrochloride
Bibliographic record
Abstract
At 25°C, methane and ethane are more soluble in water than in 7 M aqueous urea or 4.9 M aqueous guanidine hydrochloride (GuHCl); the reverse is true for larger hydrocarbons. In addition, the hydrocarbon solubility in 7 M aqueous urea or 4.9 M aqueous GuHCl increases compared with that in water on raising the temperature in the range of 545°C. These experimental data have not yet been rationalized. Using a well-founded theory of hydrophobic hydration, the present analysis indicates that the transfer of hydrocarbons from water to 7 M aqueous urea or to 4.9 M aqueous GuHCl is favored by the difference in the solutesolvent van der Waals interaction energy, and contrasted by the difference in the work of cavity creation. At room temperature, on increasing the hydrocarbon size, the first contribution rises in magnitude more rapidly than the second contribution, accounting for the threshold size occurrence. Moreover, the second contribution decreases in magnitude with an increase in temperature, becoming less unfavorable, while the first contribution is practically constant in the range of 545°C. The different temperature dependence of the work of cavity creation in such solvent systems is due to the fact that the density of 7 M aqueous urea and 4.9 M aqueous GuHCl decreases more rapidly than that of water when raising the temperature. The relationship between the density of a liquid and the work to create a cavity in it is discussed in detail.Key words: work of cavity creation, solute-solvent van der Waals interaction energy, H-bond reorganization.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".