No abstract

No abstract

Isotopic exchange equilibrium in the disproportionation reaction H2O+D2O=2 HDO was studied at 0° and 25° and over a range of deuterium compositions using a pulsed-molecular-beam mass spectrometer. The equilibrium constant K was found to be 3.75±0.07 at both temperatures. The pulsed-beam mass spectrometer was shown to be effective in minimizing the ``memory effect'' in the mass spectrometer. The experimental K is shown to be consistent with equilibrium constants for similar isotopic disproportionation reactions and with current theory.

Articles you may be interested inMolecular beam study of the mechanism of catalyzed hydrogen-deuterium exchange on platinum single crystal surfaces J. Chem. Phys. 62, 3149 (1975); 10.1063/1.430862Equilibrium constants of hydrogen-deuterium-tritium selfexchange reactions in water vapor as studied with a pulsed molecularbeam quadrupole mass filterThe equilibrium constants for hydrogen-deuterium self-exchange in hydrogen sulfide and hydrogen selenide have been studied over a wide range of deuterium atom percent using a pulsed-molecular-beam quadrupole mass filter. K HDS was found to be 3.88±0.03 at 24.0±0.4°C and KHDSe was found to be 3.92± 0.04 at 22± 1°C. The experimental results agree with calculations from spectroscopic data to within 1%. It is shown that equilibrium constants for self-exchange reactions in systems where two hydrogenic species are exchanged tend toward the geometric mean value of K = 4 in the series H;O: H,S: H 2 Se as expected from theory.

Mass-spectrometric and vacuum-thermobalance studies of barium oxide between 1365° and 1917°K yield for the equilibrium pressure of BaO gas, logPatm = − 22610 / T + 7.90. The enthalpy for the reaction BaO(a) = BaO(g) was calculated to be ΔH°298 = 110.9 ± 2.8 kcal / mole by the second-law method. The third-law date are consistent with this value if a 3Π state is assumed to be at or near (within a few hundred cm−1) the ground state of BaO(g). The heat of sublimation of the dimer Ba2O2(g) was found from the mass-spectrometer study to be about 142 kcal/mole and the heat of the reaction BaO(g) + Ba(g) = Ba2O(g) was found to be − 73 ± 15 kcal/mole at 1800°K. No reaction of barium oxide at 1800°K with O2(g) at pressures up to 10−3 atm was detected.