First Hydrolysis Constants of Hexaaquacobalt(III) and -manganese(III): Longstanding Issues Resolved
Bibliographic record
Abstract
The acid dissociation constants, Kh, of the hexaaquacobalt(III) and -manganese(III) ions are reported under conditions which minimize the problems of instability of these species at modest acidities (pH 1-4). A rapid and convenient preparation of aqueous Co(III) has been used, and the latter has been reacted with aqueous Mn(II) to form aqueous Mn(III). The noncoordinating buffer H2PIPPS (1,4-bis(3-sulfopropyl)piperazine) has been used to react with H+ and provide some control of the pH. Spectrophotometric changes, after stopped-flow mixing for Co(III) and conventional mixing for Mn(III), were used to determine the Kh values. The pKh values are as follows: Co(III), 3.10 +/- 0.07 (6.0 degrees C) and 2.92 +/- 0.04 (20.0 degrees C) in 1.0 M H+, Na+, ClO4-; Mn(III), 0.22 +/- 0.04 (7.6 degrees C) and 0.08 +/- 0.04 (20.0 degrees C) in approximately 4 M H+, Mn2+, ClO4-. Global fits of the data for each metal have been used to estimate the DeltaH degree and DeltaS degree values for Kh. It is suggested that the unusually high acidity of Mn(OH2)6(3+) may be due to a Jahn-Teller distortion effect.
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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 | 0.001 |
| 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 | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".