Sciencemadness Discussion Board

OsO[sub]4[/sub] water solubility?

chornedsnorkack - 23-8-2024 at 12:00

I have trouble finding detailed data about solubility of OsO4 and water at various temperatures.
Best source I found
https://chempedia.info/info/osmium_tetroxide/
gives 5,3 "%" at 0 C and 7,24 "%" at 25 C. Elsewhere that latter number is given as g for 100 g solvent.
Nobody seems to give any data about solubility at any temperature above 25 C.
And yet the melting point of (dry!) solute is quoted as 40 C.
Try calculating. I get that at 25 C, 1000 g (that is 55 mol...) water dissolves less than 0,3 mol OsO4.
Given that, do you expect the solubility to diverge to infinity before melting?
I would rather suspect that the solubility of OsO4 is still finite at 40 C, and that it forms two immiscible liquids (the water-rich and the less polar solution of water in OsO4. But I have not seen anyone directly state it, and give the mutual solubilities.
And then what next?
Boiling points are pretty close. Pure water 100 C, (dry) OsO4 130 C.
Liquids with far different boiling points can stay zeotropic even in nonideal solutions because although vapour pressure deviates from ideal, it does not reach an extremum. Liquids with close boiling points have a strong tendency to form azeotropes because even small deviations from ideal create extrema.
OsO4 is close to water... it has a lower boiling point than propanoic acid, which has an azeotrope and yet is miscible.
Immiscible liquids always, inherently form a low boiling azeotrope. But so do many miscible ones.
What are the azeotrope properties of OsO4? One liquid, or two? Compositions, densities of the phases? Cannot find any discussion.

bnull - 23-8-2024 at 14:16

I suggest you look inside the references below. They are given in page 5-167 of the CRC Handbook.
  1. Solubility Data Series, International Union of Pure and Applied Chemistry. Volumes 1 to 53 were published by Pergamon Press, Oxford, from 1979 to 1994; subsequent volumes were published by Oxford University Press, Oxford. The number following the colon is the volume number in the series. Current reports in the series appear in the Journal of Physical and Chemical Reference Data.
  2. Clever, H. L., and Johnston, F. J., J. Phys. Chem. Ref. Data, 9, 751, 1980.
  3. Marcus, Y., J. Phys. Chem. Ref. Data, 9, 1307, 1980.
  4. Clever, H. L., Johnson, S. A., and Derrick, M. E., J. Phys. Chem. Ref. Data, 14, 631, 1985.
  5. Clever, H. L., Johnson, S. A., and Derrick, M. E., J. Phys. Chem. Ref. Data, 21, 941, 1992.
  6. Söhnel, O., and Novotny, P., Densities of Aqueous Solutions of Inorganic Substances, Elsevier, Amsterdam, 1985.
  7. Krumgalz, B.S., Mineral Solubility in Water at Various Temperatures, Israel Oceanographic and Limnological Research Ltd., Haifa, 1994.
  8. Potter, R. W., and Clynne, M. A., J. Research U.S. Geological Survey, 6, 701, 1978; Clynne, M. A., and Potter, R. W., J. Chem. Eng. Data, 24, 338, 1979.
  9. Marshal, W. L., and Slusher, R., J. Phys. Chem., 70, 4015, 1966; Knacke, O., and Gans, W., Zeit. Phys. Chem., NF, 104, 41, 1977.
  10. Stephen, H., and Stephen, T., Solubilities of Inorganic and Organic Compounds, Vol. 1, Macmillan, New York, 1963.


I do have copies of some of them but I have a really bad habit of not renaming files after downloading and there are currently over 3100 files on the temporary folder, so...