Gaseous zirconium

On the basis of the energy levels for atomic zirconium, the selected heat capacity (J-K -mol ) for zirconium gas can be expressed by the following two temperature dependent equations  

The thermal functions of Zr(g) listed in Table V-7 are those derived by [85CHA/DAV] (or calculated from those values listed by [85CHA/DAV]). The equations listed above for the heat capacity of zirconium gas and equations for other thermodynamic properties derived from these equations reproduce the values listed in Table V-7 to within 0.5%. As is evident from the data presented in the table, the heat capacity exhibits a maximum at about 435 K and a minimum at 975 K. This behaviour also occurs for other metals such as titanium and iron. 

The selected values for the heat capacity and standard entropy of gaseous zirconium at 298.15 K and atmospheric pressure are  

The selected value of the enthalpy of formation of zirconium gas is the weighted average of the data from the various studies listed in Table V-8. 

When combined with the relevant entropy values at 298.15 K, this gives  

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Method No 308. Delay Powder, Non-Gaseous (Zirconium-Nickel Alloy Type) Type I (delay 2-sec) - Ba chromate 60.0, 70/30 Zr-Ni alloy 26.0 8t K perchlorate 14.0% ... 

Table 16 Bond Lengths (A) and Vibrational Frequencies" (cm-1) in Gaseous Zirconium(IV) and Hafnium(IV)...

Ackermann RJ, Rauh EG, Alexander CA (1975) The thermodynamic properties of gaseous zirconium oxide. High Temp Sci 7 304... 

The compounds M2Zr(Hf)Cle have been synthesized by fusing calculated quantities of the simple salts in sealed quartz tubes (371), or by reacting gaseous zirconium tetrachloride at one atmosphere with Na(K)CI in a double-bulbed evacuated tube in which the tetrachloride... 

Table V-8 Third law heat of sublimation values for gaseous zirconium including the p-T equation and the temperature range over which the measurements were conducted.

Barkovskii et al. [88BAR/GOR], [91BAR/TSI] studied the equilibrium between the various gaseous zirconium fluorides according to the following reactions ... 

Geometric structure and molecular parameter data were used by [97VIS/COR] to determine the heat capacity and entropy of the gaseous zirconium chlorides at... 

K. The predicted structure of the tetrachloride is tetrahedral, that of the trichloride is planar and the dichloride is linear. From the measured and estimated data, [97V1S/COR] calculated the following heat capacity and entropy values for the gaseous zirconium chlorides ... 

There have been no studies of the enthalpies of formation of the lower gaseous zirconium bromides. Values for these parameters have been estimated by [97V1S/COR] from the bond energies of the other zirconium halides. The values estimated by [97V1S/COR] are, Af//° (ZrBr, g, 298.15 K) = (366 25) kJ-mol, Af//° (ZrBrj, g,... 

The values for the lower gaseous zirconium bromides, ZrBr(g) to ZrBr3(g) are noted by this review but not selected due to the laek of experimental data for the enthalpies of formation. The Gibbs energy of formation for ZrBr4(g) is selected by this review. 

Kleinschmidt et al. [78KLE/CUB] studied the thermodynamics of the gaseous zirconium iodides at elevated temperatures using Knudsen cell mass spectrometry. The formation of Zrl3(g) over the range 1100 to 1400 K was studied using two independent reaction mechanisms ... 

All of the members of the final review team contributed, if not text, then comments to all of the chapters of the book. Their primary responsibilities for the different sections/chapters were divided as follows. Paul Brown prepared the introduction, and the sections on elemental zirconium, the zirconyl ion, the gaseous zirconium oxides, zirconium hydride, the halogen compounds and complexes, the chalcogen compounds and complexes, the Group 15 compounds and complexes, zirconium carbides and silicates. He was assisted by Christian Ekberg in the interpretation of aqueous zirconium complexes in these sections. Some initial work was done by Ken Jackson on the zirconium sulphate, nitrate and phosphate compounds and complexes. Bernd Grambow was responsible for the drafting of the sections on zirconium hydrolysis, the ion and the section on crystalline and amorphous zirconium oxides. Enzo Curti drafted the section on the zirconium carbonates. 

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