Volume 7, Issue 3, July 1978
Index of content:
7(1978); http://dx.doi.org/10.1063/1.555579View Description Hide Description
An analytic thermodynamicsurface has been fitted to the experimental data for ammonia for the temperature range extending from the triple point to 750 kelvins and for the pressure range extending from the dilute gas to 500 MPa (5000 bar). Values for the thermodynamic properties are tabulated at closely spaced intervals. A major part of the correlation was devoted to a study of the extent to which thermodynamic inconsistencies degrade the accuracy of the derived properties. This study focused as much on methods for correlating the data as on the data themselves. As a consequence, we are able to assign close tolerances to the tabulated thermodynamic properties over the range of the surface, including properties for the coexisting phases and even close to the liquid‐vapor critical point.
7(1978); http://dx.doi.org/10.1063/1.555580View Description Hide Description
The thermodynamic tabulations previously published in NSRDS–NBS 37, the 1974 Supplement (J. Phys. Chem. Ref. Data 3, 311 (1974), and the 1975 Supplement (J. Phys. Chem. Ref. Data 4, 1 (1975) are extended by 131 new and revised tables. The JANAF Thermochemical Tables cover the thermodynamic properties over a wide temperature range with single phase tables for the crystal, liquid, and ideal gas state. The properties given are heat capacity,entropy,Gibbs energy function, enthalpy, enthalpy of formation, Gibbls energy of formation, and the logarithm of the equilibrium constant for formation of each compound from the elements in their standard reference states. Each tabulation lists all pertinent input data and contains a critical evaluation of the literature upon which these values are based. Literature references are given.
7(1978); http://dx.doi.org/10.1063/1.555581View Description Hide Description
The paper re‐analyzes the results of earlier, very precise measurements of the viscosity of water at essentially atmospheric pressure. This is done in terms of a new, theoretically‐based equation for the operation of a capillary viscometer rather than in terms of semi‐empirical equations used by the original authors. The new analysis eliminates possible systematic errors and permits the establishment of realistic error bounds for water in its role as a standard reference substance for viscosity. The latter are smaller than those embodied in the most recent International Formulation. Standard values of the ratio of viscosity at a temperature T to its value at 20 °C have been derived from the re‐analyzed data because the uncertainty of this ratio is an order of magnitude smaller than that of the absolute values. The ratios are used to generate absolute values with the aid of the standard NBS datum μ=1002.0 μPa s at 20 °C. The viscosity ratios have been correlated with the aid of two empirical equations. The more accurate equation covers the range 0 °C?t ?40 °C with an uncertainty of ±0.05%. The less accurate equation covers the wider range −8 °C?t?150 °C with the more limited accuracy of ±0.2%. The two empirical equations are compatible with each other to 0.09%.
7(1978); http://dx.doi.org/10.1063/1.555582View Description Hide Description
Data from the literature on the molar volume of solid oxygen have been compiled and critically analyzed. A correlated and thermodynamically consistent set of molar volumes, including the volume changes at the various solid phase transitions, is presented. Evidence for the existence of a δ‐solid phase is reviewed. Uncertainties in the data and in the recommended set of values are discussed.
7(1978); http://dx.doi.org/10.1063/1.555583View Description Hide Description
This work reviews and discuss the available data and information on the thermal conductivity of ten selected binary alloy systems and presents the recommended values resulting from critical evaluation, analysis, and synthesis of the available data. The ten binary alloy systems selected are the systems of aluminum‐copper, aluminum‐magnesium, copper‐gold, copper‐nickel, copper‐palladium; copper‐zinc, gold‐palladium, gold‐silver, iron‐nickel, and silver‐palladium. The recommended values given include values of the total thermal conductivity, electronic thermal conductivity, and lattice thermal conductivity. The uncertainty of the values is generally of the order of ±10%. The values for each of the alloy systems except two are given for 25 alloy compositions: 0.5, 1, 3, 5, 10(5)95,97,99, and 99.5%. For most of the alloy compositions, the values cover the temperature range from 4 K to the solidus temperature or 1200 K. In addition, reliable methods for the estimation of the electronic and lattice thermal conductivities of alloys have been developed in this study.
Semi‐empirical extrapolation and estimation of rate constants for abstraction of H from methane by H, O, HO, and O27(1978); http://dx.doi.org/10.1063/1.555577View Description Hide Description
It has been concluded that for extrapolating rate constants of atom transfer reactions to and from high temperatures, a useful form of the rate constant is k=A T 2 exp(−C/T), where A and C are fitted constants. For k/[cm3/(mol s)] and T K, on the basis of previous experimental data, the values of log A and C for the following reactions are: H+CH4=H2+CH3, log A=7.15, C=4449; O+CH4=OH+CH3 log A=6.71, C=3240; HO+CH4 =H2O+CH3, log A=6.93, C=1485 and O2+CH4=O2H+CH3, log A=6.93, C=26153. At all temperatures, abstraction by HO is faster than by O. The form of the rate constant is equivalent to assuming that ΔC p 0‡, the heat capacity at the constant pressure of activation, is zero. When ΔC p O‡, was estimated and assumed to be constant (in principle, a more accurate assumption than ΔC p O‡ =0), the fit to the experimental data was slightly worse. It is confirmed that at 400 to 700 K, the kinetic and thermodynamicequilibrium constants for the reaction H+CH4 =H2+CH3 are significantly different. (At 1340 K, they are in agreement.)
7(1978); http://dx.doi.org/10.1063/1.555578View Description Hide Description
The energy levels of the vanadium atom in all of its stages of ionization, as derived from the analyses of atomic spectra, have been critically compiled. In cases where only line classifications are given in the literature, level values have been derived. The percentages for the two leading components of the calculated eigenvectors of the levels are given where available. Ionization energies and experimental g‐values are also given.