Thermodynamics of Polyborates under Hydrothermal Conditions: Formation Constants and Limiting Conductivities of Triborate and Diborate
Bibliographic record
Abstract
Abstract Frequency-dependent molar electrical conductivities for aqueous solutions of boric acid with small additions of sodium hydroxide or potassium hydroxide have been measured from 298 to 573 K at 12 MPa to an accuracy of ±3%, using a unique high-precision flow-through AC conductance instrument. The measurements were made to yield accurate polyborate equilibrium formation constants and limiting conductivities under the primary coolant conditions of pressurized water nuclear reactors (PWRs). Complementary measurements from T = 283 K to T = 313 K at p = 0.1 MPa were completed using a commercial conductivity probe to extend the data to lower temperatures. Up to 423 K, measurements were performed under conditions where the triborate ion B3O3(OH)4– is the major anionic species in solution. At temperatures above 473 K, the conditions favored the formation of a different anionic species, which was assigned to be the diborate ion B2(OH)7–. The analysis of the concentration dependence of the molar conductivity data using the TBBK equation yielded limiting conductivities, λ0, and formation constants, Kb31,m and Kb21,m, for triborate and diborate from 283 to 473 K, and from 473 to 573 K, respectively. These results are consistent with the only other experimental study that has reported equilibrium constants for aqueous polyborates above 373 K (Mesmer et al. Inorg. Chem. 1972, 11, 537). The limiting conductivities are the first to be reported in the literature.
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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 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".