Ferric <i>trans</i>-1,2-Diaminocyclohexanetetraacetic Acid (Fe<sup>3+</sup>CDTA<sup>4-</sup>/Fe<sup>3+</sup>OH<sup>-</sup>CDTA<sup>4-</sup>) in NaCl Aqueous Solutions: Effect of Temperature on the Hydroxy Complex Formation Thermodynamic Constant and on the Activity Coefficient Ion-Interaction Parameters
Bibliographic record
Abstract
The impact of the variation of temperature from (280 to 323) K on the thermodynamic equilibrium constant ( K °) for the Fe 3+ CDTA 4- + OH - ⇄ Fe 3+ OH - CDTA 4- complex formation reaction (CDTA is trans -1,2-diaminocyclohexanetetraacetic acid) was investigated in alkaline solutions. K ° is obtained by multiplying the equilibrium reaction product ( K m ) measured from species molal concentrations by the activity coefficient quotient (γ ± ) predicted by either the Hückel, Bromley, Scatchard, or Pitzer models, all of which required knowledge of ion-interaction empirical constants. For each temperature set at (280, 288, 298, 305, 313, 323) K ± 1 K, the measured K m values acquired for a multitude of sodium chloride solutions of (1.5 × 10 -4 to 0.95) mol kg -1 were fitted on the ( K ° /γ ± ) relationship for all four activity coefficient models. K ° and ion-interaction empirical constants were obtained from this action. K ° values computed from the six temperature sets were used to evaluate the reaction enthalpy (Δ r H m ) and entropy (Δ r S m ) associated with the above complex formation reaction. Δ r H m was estimated to be (−17.7 ± 0.5) kJ mol -1, whereas Δ r S m was fixed at 23.0 J mol -1 K -1 . It was also determined that most of the models ion-interaction empirical constants do not change with temperature in a recognizable way within the studied range. The only exception involves Pitzer's ion-interaction summations (Σ, Σ ) where a slight but definite trend was observed in relation to 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 | 0.000 |
| 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) | 0.001 | 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".