An Experimental Study of the Solubility and Speciation of MoO3(s) in Hydrothermal Fluids at Temperatures up to 350°C
Bibliographic record
Abstract
Abstract The solubility of molybdenum trioxide (MoO3(s)) in aqueous solutions has been investigated experimentally at 250°, 300°, and 350°C and saturated water vapor pressure, and total Na concentrations ranging from 0 to 3 molal (m). Results of these experiments show that the solubility of MoO3(s) increases with increasing temperature and at 350°C can reach several thousand parts per million at high salinity (>1 m NaCl). At low Na+ activity, MoO3(s) dissolves dominantly as HMoO4,− whereas at high Na+ activity, the dominant species is NaHMoO40. The two dissolution reactions are MoO3(s)+H2O=HMoO4−+H+(1) and MoO3(s)+H2O+Na+=NaHMoO40+H+.(2) The values of the logarithms of the equilibrium constants for reaction (1) are –5.20 ± 0.12, –5.31 ± 0.17, and –5.50 ± 0.09 at 250°, 300°, and 350°C, respectively, and for reaction (2) the values are –3.40 ± 0.11, –3.25 ± 0.19, and –2.97 ± 0.09 for the same temperatures. In combination, these equilibrium constants yield equilibrium constants for the reaction relating the two aqueous species: Na++HMoO4−=NaHMoO40.(3) The values of the logarithms of the equilibrium constants for reaction (3) are 1.80 ± 0.16, 2.06 ± 0.25, and 2.53 ± 0.13 at 250°, 300°, and 350°C, respectively. Calculations, based on the results of this study and thermodynamic data available for other species, suggest strongly that in ore-forming hydrothermal systems, molybdenum is transported mainly as NaHMoO40 and deposits as molybdenite in response to cooling and possibly a reduction in fO2.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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".