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, V ϕ, and heat capacities, C p,ϕ, were calculated and corrected for speciation to obtain standard partial molar properties V ° and C p °, for the species DMEA(aq) and DMEAH + Cl – (aq). The experimental values for V ° and C p °, 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 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 | 0.001 | 0.003 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
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".