Enthalpy and entropy increments above 298.degree.K. and a .SIGMA.-plot treatment of vaporization data for niobium pentachloride

Thermodynamic properties of gaseous niobium chlorides

“…The enthalpy of formation of solid NbClE has been determined,14-16 as well as the enthalpy of formation of several solid lower chlorides.14 '17 The enthalpy and entropy increments above 298 °K for NbCls have been determined in our laboratory. 10 Schafer, et al, 18 have investigated the decomposition of solid NbCl4 into solid NbCls and gaseous NbCl5. Thermodynamic functions for gaseous NbCls have been reported by Werder, et al.,ia based on the results of spectroscopic studies and using the structural data of Skinner and Sutton.20 Knowledge of the thermodynamic properties of the lower valent gaseous chlorides of niobium is scarce, and in an attempt to provide needed data we have carried out the transpiration and mass spectrometer experiments described below.…”

“…Afef = y4fef(NbCl4,g) -fef(NbCI6,g) -V4fef(Nb,s) (10) AG°T (11) G°T = R In KM (12) we calculate fef(NbCl4,g) = -96 ± 5 cal/ (deg mol) at…”

“…A review of the chemical and physical properties is given by Pascal.2 Several papers on the vapor pressure of NbClE have been published.3-9 We have previously reviewed and correlated most of these data. 10 The vapor pressure of NbCl4 has been studied by Schafer and Bayer,11 and of NbOCl3 by Schafer and Kahlenberg12 and Saeki,et…”

“…TableIare those corresponding to the temperatures measured at the NbCle saturator bulb, the pressures being obtained from literature data 10. The symbols Pnb* and Pci* refer to pressures calculated from the moles of Nb and Cl collected.…”

The synthesis and properties of the hexachloroniobates and hexachlorotantalates of Na, K, Rb, and Cs

“…The first method was to sublime the salt in a stream o f helium saturated with thionyl chloride as described by Keneshea et a/. (5). Oxychloride and water reacted according t o…”