Thermodynamic Properties of Normal Hydrogen

Temperature K Pressure MPa Density mol/dm3 Volume dm3/mol Int. energy kj/mol Enthalpy kj/mol Entropy kJ/(mol K) c, kJ/(mol K) Q kJ/(mol-K) Sound speed m/s Joule-Thomson K/MPa Therm, cond. mW/(m K) Viscosity TPa s 

TABLE 2-223 Thermodynamic Properties of Normal Hydrogen (Concluded) 

The uncertainties in density are 0.1% in the liquid phase, 0.25% in the vapor phase, and 0.2% in the supercritical region. The uncertainty in heat capacity is 3%, and the uncertainty in speed of sound is 2% in the liquid phase and 1% elsewhere. The uncertainty in viscosity ranges from 4% to 15%. The uncertainty in thermal conductivity below 100 K is estimated to be 3% below 150 atm and up to 10% below 700 atm. For temperatures around 100 K at low densities, the uncertainty is about 1%. Above 100 K, the uncertainty is estimated to be on the order of 10%. 

Temperature Pressure Density Volume Int. energy Enthalpy Entropy Cp Sound speed Joule-Thomson Therm, cond. Viscosity 

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John W. Dean, A Tabulation of the Thermodynamic Properties of Normal Hydrogen from Low Temperatures to i00°X and from 1 to 100 Atmospheres, National Bureau of Standards Technical Note 120, Office of Technical Services, Washington, D.C., 1961, 71 pp. 

The principal sources ot P-V-T data used in this correlation and compilation were from reports of H. L. Johnston and his co-workers [1,2] and from National Bureau of Standards Research Paper RP1932 [3]. Other reports and publications reviewed include a paper by Friedman and Hilsenrath [4] on thermodynamic and transport properties, a report of White and Johnston [5] on the thermodynamic properties of liquid normal hydrogen, and another by White and Johnston [6] on the thermodynamic properties of gaseous hydrogen. 

Many of the thermodynamic and transport properties of liquid water can be qualitatively understood if attention is focused on the statistical properties of the hydrogen bond network [9]. As an example, let us observe the temperature dependence of density and entropy. As temperature decreases, the number of intact bonds increases and the coordination number is closer to the ideal value 4. Because of the large free volume available the temperature decrease is associated with an increase of the local molecular volume. This effect superimposes of course to the classical anharmonic effects which dominate at high temperature, when the number of intact bonds is smaller. The consequence of both effects is a maximum on the temperature dependence of the liquid density. This maximum is actually at 4°C for normal water and 11 °C for heavy water. Such a large isotopic effect can also be understood because the larger mass of the deuterium makes the hydrogen bonds more stable. 

D. White and H. L. Johnston. The Thermodynamic Properties of Liquid Normal Hydrogen Between the Boiling Point and the Critical Temperature and up to 150 Atmospheres Pressure, Ohio State University, Cryogenic Laboratory Technical Report Number TR 264-23 (Feb. 1, 1953). 

Standard oxidation potentials referred to the normal hydrogen electrode (E°) for the divalent and trivalent lanthanide aquo ions are given in table 24.8 based primarily on the selected experimental results compiled by Chariot et al. (1971) and the systematic correlations summarized by Nugent (1975). Only Eu and Yb can persist for times of the order of minutes to hours in dilute acid solution, and can be readily produced by reduction of the trivalent ionic species (Laitinen and Taebel, 1941 Laitinen, 1942 Christensen et al., 1973). The value of E° = -0.43 V for the Eu(II-III) couple quoted in many previous compilations was obtained using both potentiometric and polarographic techniques. However, in a reevaluation of the solution thermodynamic properties of europium, Morss and Haug (1973) recommended the value E° = —0.35 V. 

In order to obtain thermodynamic properties of hydride compositions other than the hydrogen-deficient dihydride phase (which is normally in equilibrium with the metal phase), it is necessary to use partial molal quantities of hydrogen in the hydride, as illustrated for the calculation of enthalpy (n the following expression ... 

Tables 2,3, and 4 outline many of the physical and thermodynamic properties ofpara- and normal hydrogen in the sohd, hquid, and gaseous states, respectively. Extensive tabulations of all the thermodynamic and transport properties hsted in these tables from the triple point to 3000 K and at 0.01—100 MPa (1—14,500 psi) are available (5,39). Additional properties, including accommodation coefficients, thermal diffusivity, virial coefficients, index of refraction, Joule-Thorns on coefficients, Prandti numbers, vapor pressures, infrared absorption, and heat transfer and thermal transpiration parameters are also available (5,40). Thermodynamic properties for hydrogen at 300—20,000 K and 10 Pa to 10.4 MPa (lO " -103 atm) (41) and transport properties at 1,000—30,000 K and 0.1—3.0 MPa (1—30 atm) (42) have been compiled. Enthalpy—entropy tabulations for hydrogen over the range 3—100,000 K and 0.001—101.3 MPa (0.01—1000 atm) have been made (43). Many physical properties for the other isotopes of hydrogen (deuterium and tritium) have also been compiled (44).

The process gas of ethylene plants and methyl tertiary butyl ether plants is normally a hydrogen/ methane mixture. The molecular weight of the gas in such processes ranges from 3.5 to 14. The tliermodynamic behavior of hydrogen/methane mixtures has been and continues to be extensively researched. The gas dynamic design of turboexpanders, which are extensively used in such plants, depends on the equations of state of the process gas. Optimum performance of the turboexpander and associated equipment demands accurate thermodynamic properties for a wide range of process gas conditions. 

White, Friedman, and Johnston (343) have measured the critical constants for normal hydrogen and have found 33.244 K. and 12.797 atmospheres. Woolley, Scott, and Brickwedde have presented data on the dissociation energy and the thermodynamic properties for the ideal diatomic gas, including contributions from nuclear spin. We have omitted the spin entropy in compiling our tables. Thermodynamic properties for the ideal monatomic gas have been computed at the National Bureau of Standards (395). Note that the reference state represents 2 gram atomic weights for this element. 

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