The behavior of eighteen metal 8-hydroxyquinolates upon heating in vacuo has been investigated. Many of the compounds were observed to sublime completely, without appreciable decomposition, over fairly narrow temperature ranges. The temperature range of volatilization was found to be a function of metal ion electronegativity for the divalent metal 8hydroxyquinolates. In contrast to this behavior, nearly all of the trivalent metal 8-hydroxyquinolates volatilized over the same temperature range, 250 to 350°. Sublimation of the Ca(II) and Bi(III) 8-hydroxyquinolates was accompanied (or preceded) by significant decomposition, while the Ba(II), Sr(II) and La(III) compounds did not sublime appreciably, but decomposed at sufficiently high temperatures.
The presented results obtained by weighing the zinc electrode in the electrolyte during the discharge cycle agree with data of others and explain why the capacity of the zinc electrode is a function of the amount of electrolyte used and roughly linearly dependent on the concentration of the potassium hydroxide up to about 10M. Previous results, that part of the zinc goes into solution, part is precipitated out as oxide or hydroxide, and that some adherent layer is formed which finally forces the potential of the plate to drop sharply, are substantiated on a more quantitative basis. The experiments also indicate that the relatively thick scale formed might not be the sole cause of the passivation phenomena.
The appearance potentials of C+, CH+, and CH2+ in the mass spectra of methylene, methyl, and methane are found to be mutually consistent and when combined with the spectroscopic value of the ionization potential of the carbon atom (11.26 ev) lead to 15.5±0.5 ev/molecule for the heat of atomization of methane. This value (15.5) when further combined with the heat of formation of methane (—0.78 ev/molecule) and the dissociation energy of H2 (4.48 ev/molecule) yields 5.76 ev/atmos or 133 kcal/mole for the heat of sublimation of graphite.
The set of appearance potentials confirmed the spectroscopic value for the heat of dissociation of CH+ (3.6 ev/molecule) and yield the following additional energetic quantities: D(CH2–H) = 3.75±0.3 ev/molecule, D(CH–H) = 3.99±0.3 ev/molecule, D(CH3+–H) = 1.34±0.1 ev/molecule, D(CH2+–H) = 5.54±0.2 ev/molecule, and D(CH+–H) = 3.37±0.2 ev/molecule. Earlier determinations of Iz(CH4), Iz(CH3) and D(CH3–H) are confirmed (within the experimental error) and the ionization potential of the methylene radical, Iz(CH2), is found to be 11.75±0.1 ev/molecule.
Combination of the appearance potentials of CH2+ in the methane and diazomethane mass spectra gives 46±6 kcal/mole for the heat of formation of diazomethane.
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