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
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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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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 | 0.002 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.000 | 0.002 |
| 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 it