The uncertainties in the condensed-phase thermodynamic functions arise from (1) the possible existence of a solid-solid phase transition in the temperature range 2160 to 2370 K and (2) the uncertainty in the estimated value of the liquid heat capacity which is on the order of 40%. While these uncertainties affect the partial pressures of plutonium oxides by a factor of 10 at 4000 K, they are not limiting because, at that temperature, the total pressure is due essentially entirely to O2 and 0. [Pg.143]

In this paper we describe (1) the gas-phase thermodynamic functions (2) the condensed-phase thermodynamic functions (3) the oxygen potential (and the phase boundaries that are consistent with It) and (4) the resulting vapor pressure and composition as functions of temperature and composition of the condensed phase. [Pg.128]

With these formulas for Um and Sm, equations can be directly derived for the other thermodynamic functions Hm, Am, and Gm. For condensed phases Hm = Um to a very good approximation. For gases, assumed ideal, H0 = U0 and Hm = Um + RT, giving [Pg.143]

Figure 4 Equilibrium CVD phase diagram for the Nb-Ge-H-CI system. The diagram was constructed from thermodynamic calculation results and depicts the condensed phases which form as a function of experimental variables. The Nb/(Nb+Ge) values are reactant gas concentrations. After Wan.9 |

The process we have followed is identical with the one we used previously for the uranium/oxygen (U/0) system (1-2) and is summarized by the procedure that is shown in Figure 1 Thermodynamic functions for the gas-phase molecules were obtained previously ( ) from experimental spectroscopic data and estimates of molecular parameters. The functions for the condensed phase have been calculated from an assessment of the available data, including the heat capacity as a function of temperature ( ). The oxygen potential is found from extension into the liquid phase of a model that was derived for the solid phase. Thus, we have all the information needed to apply the procedure outlined in Figure 1. [Pg.124]

Use the NIST WEB BOOK (http //webbook.nist.gov) to find the vapor pressure of water as a function of temperature over the range from 300 K to 600 K. When you reach the home page foir the WEBBOOK, cUck on the NIST Chemistry Webbook, cfick on Name under search options, type water in the space for name, cfick on thermodynamic data, cfick on condensed phase, cfick on saturation properties, and insert the temperature [Pg.209]

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