Part One: Further investigation of energy transfer processes in the unimolecular decomposition of nitryl chloride. Part Two: Decomposition of nitrogen pentoxide in the presence of nitric oxide. IV. Effect of noble gases. Part Three: Theoretical pre-exponential factors for hydrogen atom abstraction reactions. Part Four: Carbon isotope effect during oxidation of carbon monoxide with nitrogen dioxide

The unimolecular decomposition of nitryl chloride was investigated in the pressure range 10 to 500mm. and the temperature range 141 to 205°C. Relative efficiencies of foreign gases were found to vary slightly, if at all, over this range of conditions. The reaction was observed to be partially heterogeneous in the Pyrex reaction cell used. The results of this work are in agreement with those of Volpe and Cordes at low pressures and with those of Casaletto at high pressures. The discrepancies between the relative efficiencies obtained by Volpe and those obtained Schumacher and Sprenger are probably due to effects of heterogeneity in the work of Schumacher and Sprenger. The data obtained in this work were interpreted in terms of the Lindemann mechanisms. Relative efficiencies were calculated by means of the Schwartz-Slavsky-Herzfeld theory and the Landau Teller theory; the latter theory gave results in qualitative agreement with the available experimental data. Relative efficiencies of the noble gases and of carbon tetrachloride for the decomposition of nitrogen pentoxide at 50°C in the pressure range 0.1 to 3.0 mm., are reported in Part Two of this thesis. It was found that deactivation of activated reactant molecules does not occur on every collision. Part Three of this thesis, "Theoretical Pre-exponential Factors for Hydrogen Atom Abstraction Reactions," contains its own abstract. Pre-exponential factors were calculated by means of Eyring's activated complex theory for ten bimolecular reactions. Part Four of this thesis "Carbon Isotope Effect during Oxidation of Carbon Monoxide with Nitrogen Dioxide," contains its own abstract.