Vapor Pressures of Platinum, Iridium, and Rhodium.
- 1 July 1961
- journal article
- Published by National Institute of Standards and Technology (NIST) in Journal of Research of the National Bureau of Standards Section A: Physics and Chemistry
- Vol. 65 (4) , 289-295
- https://doi.org/10.6028/jres.065A.034
Abstract
The vapor pressures of platinum, iridium, and rhodium have been measured using a microbalance technique based on the Langmuir method. Heats of sublimation at 298 °K were calculated with the aid of free energy functions. The least square lines for the vapor pressure data, the heats of sublimation, and the normal boiling points obtained were as follows: Platinum: Log P atm = 6.761 - 27 , 575 T ( 1 , 916 to 2 , 042 ° K ) Δ H s ° ( 298 ) = 134.9 ± 1.0 kcal / mole bp = 4 , 100 ± 100 ° K Iridium: Log P atm = 7.139 - 33 , 337 T ( 1 , 986 to 2 , 260 ° K ) Δ H s ° ( 298 ) = 159.9 ± 2.0 kcal / mole bp = 4 , 800 ± 100 ° K Rhodium: Log P atm = 6.894 - 27 , 276 T ( 1 , 709 to 2 , 075 ° K ) Δ H s ° ( 298 ) = 132.5 ± 2.0 kcal / mole bp = 4 , 000 ± 100 ° K . The indicated uncertainties are estimates of the overall limits of error. The value of the gas constant R used in the calculation of Δ H s ° is 1.98726 cal/degree mole.Keywords
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