VAPOR PRESSURE OF THORIUM¹

Abstract

The vapor pressure of solid thorium was determined over the temperature interval 1757 to 1956°K. by the vacuum evaporation method of Langmuir. Special purification of the thorium was necessary since traces of Th02 react with thorium to give ThO(g). Thorium also reacts with residual gaseous oxygen in the vacuum system to form ThO(g). The latter effect was found to be negligible at residual oxygen pressures of less than 2 X 10 ~* mm. The vapor pressure equation for Th(s) -Th(g) is log Patm = -28,780 =fc 620/7' . + 5.991 ± 0.333. These results yield values of Aff°298(subi> of 137.3 ± 2.8 keal./ mole and 136.6 ± 0.5 kcal./mole from a slope and third law determination, respectively. From an estimate of the pressure of ThO(g) over Th(s) containing ThO^s), Í)0°(ThO) = 196 kcal./mole.(1) This work was supported by the Atomic Energy Commission• This paper has been presented in part before the Division of Physical Chemistry at the 135th National Meeting of the American Chemical Society in April, 1959. (2) S. Dushman, "Scientific Foundations of Vacuum Technique,"

The Electric Conductivity of Molten HgI2 -HgBr2 and Hgl2 -Sbl3 Binary Mixtures

“…According to Mclntyre and Janz 4 , the carriers of electric current in a HgI2-HgBr2 mixture should be considered to be the Hgl + , Hgl3, HgBr + and HgBr3 ions. With this assumption and using the significant structure theory of liquids proposed by Eyring et al 15 , Mu Shik Jhon et al 16 have calculated some physical properties of mercury halides in good agreement with experiment.…”

“…Grantham and Yosim 2 have shown that the negative temperature coefficient of electric conductivity in the melts is a consequence of the decrease in density and increase in covalent character of the melt as the temperature increases. Such an explanation is satisfactory in view of the work of Darnell and McCollum 4 , who achieved a large increase in ionicity of molten Hgl2 by subjecting it to a high pressure.…”

Vaporization of Thorium Dicarbide1

“…UO(g) has been found to be the most important species in equilibrium with a mixture of U(l) and U02(s),37 just as Th(s) containing dissolved 0 produces large amounts of ThO(g). 38 No detailed theoretical explanation of such behavior has yet been made. However, it is likely that other gaseous carbide and oxide complexes will soon be identified and that species ratios as a function of stoichiometry will be better explored.…”

Kinetics and Mechanisms in the Oxidation of Metal Vapors

“…The addition of O2 in the upper + chamber enhances the intensity rh0 2 + peak and dec-eases the intensity of Th Figure 6C. When the electron beam is turned off, all peaks disappear with the exception of ThcT which proves that this ion is formed directly through a chemiionization process such as shown by equation reaction (3 «•»'""»■»"i-w™BnwP^«ppwiWTOW|WWPö*w*"T'w»PPiw^^ Further mass spectrometric and spectroscopic work is now in progress.…”