Interim Report On The Thermodynamics Of Chemical Species Important

Author : National Bureau of Standards
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (113 download)

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Download or read book Interim Report on the Thermodynamics of Chemical Species Important to Rocket Technology written by National Bureau of Standards and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This report presents in detail the results and critical analyses of several recently completed NBS experimental investigations, literature surveys, and developments of new measurement methods. The heat of formation of C¿̐ưF was measured by burning it with H2 in a flame calorimeter; the result is shown to favor the new lower dissociation energy of F2 32.0 kcal per mol, but not unambiguously owing to uncertain interpretations of necessary auxiliary data. A transpiration search for chemical reaction between HF and gaseous A¿̐ưF3 revealed none detectable, near 1200 K and up to 0.75 atm of HF, beyond the sensitivity of the method (1-2Z). Selected values of the standard heats, free energies, and entropies of formation of a number of niobium compounds resulting from an up-to-date critical review of the literature are discussed and tabulated. The heat capacity, electrical resistivity, and hemispherical total and normal spectral emittances of tantalum metal were measured by an accurate high-speed pulse technique from 1900 to 3200 K; the spectral emittance (at a wavelength of 650 nm) was found to decrease approximately 3.5% during the initial one-third of the melting period. The pulse heating technique is adapted to measuring the melting points of thin-wire electrical conductors above 2000 K, and checked by finding 2044 K (estimated uncertainty, + 5 K) for platinum (accepted value, 2045 K). In designing a transpiration technique for seeking unknown higher gaseous hydrates of beryllia above 2000 K, the results of detailed calculations are presented which show that sufficiently accurate temperature measurement, dubious by pyrometer, can probably be met by comparison with the volatility of gold and application of several corrections. The results of several investigations of barium and one of its compounds are presented. Accurate heat-capacity and enthalpy measurements on the metal from 18 to 1173 K show several anomalies, unusually high heat capacities, and a heat of fusion which is thought to reflect solubility of BaO impurity in the liquid metal. Based on these new thermal data, a third-law analysis was made of the existing vapor-pressure data, leading to a heat of sublimation of the metal whose uncertainty is believed to be due largely to uncertainties in the published vapor pressures. Atomic barium, deposited in solid-argon matrices containing isotopic varieties of 0^, yielded infrared values for two stretching frequencies of several isotopic forms of the BaO2 molecule; the (much weaker) 0-0 stretching frequency is interpreted as evidence that the molecule is essentially Ba02.