Standard Partial Molar Heat Capacities and Volumes of Aqueous <i>N</i>,<i>N</i>-Dimethylethanolamine and <i>N</i>,<i>N</i>-Dimethylethanolammonium Chloride from 283.15 to 393.15 K, and Ionization Constants to 598.15 K
Bibliographic record
Abstract
Densities for dilute aqueous solutions of N,N-dimethylethanolamine (DMEA) and N,N-dimethylethanolammonium chloride (DMEAH+Cl–) were measured relative to water at 283.15 K ≤ T ≤ 363.15 K and 0.1 MPa using vibrating tube densimeters. Volumetric heat capacities of the same solutions were measured at 283.15 K ≤ T ≤ 393.15 K and 0.4 MPa using twin fixed-cell, power-compensation, differential-temperature scanning nanocalorimeters. From these measurements, apparent molar volumes, Vϕ, and heat capacities, Cp,ϕ, were calculated and corrected for speciation to obtain standard partial molar properties V° and Cp°, for the species DMEA(aq) and DMEAH+Cl–(aq). The experimental values for V° and Cp°, measured in this work were combined with high temperature values reported by Bulemela and Tremaine (J. Phys. Chem. B 2008, 112, 5626–5645) over the range 423.15 to 598.15 K to derive parameters for the semiempirical “density” model that expresses the standard partial molar thermodynamic properties of aqueous species as a function of temperature and solvent density. The fitted parameters were combined with critically evaluated literature values for the standard molar Gibbs energy and enthalpy of reaction at 298.15 K to obtain values for the ionization constant of N,N-dimethylethanolamine from 283.15 to 598.15 K at steam saturation pressure.
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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 | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 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".