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Title: Some combination reactions of free atoms
Author: Chowdhury, Abul Kasem
ISNI:       0000 0001 3548 7304
Awarding Body: University of London
Current Institution: Royal Holloway, University of London
Date of Award: 1978
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A kinetic study has been made of the reactions: O + O2 + M → O3 + M (M = O2, CO2, He, Ar) 1.1; O + SO 2 + M → SO3 + M (M= SO2, N2, He ,Ar) 2.1; and the rate constants determined at different temperatures. An improved discharge flow apparatus was designed and used for the work; the first order decay of oxygen atoms was followed by chemiluminescence techniques. Rate constants for surface reactions were measured by an extension of the technique; this permitted the measurement of surface recombination efficiencies in the presence and absence of O2. Recombination coefficients for each third body were determined and the corresponding recombination efficiencies were evaluated. For reaction 1.1, the rate of reaction decreased with increasing temperature. The Arrhenius plots in the presence of all third bodies, except CO2, were non-linear; this was indicative of the presence of different reactions each with its own energy of activation. A possible mechanism for the reaction is advanced. The high surface recombination efficiency depended on the ambient gas, decreasing in the order Ar > He > CO2. This suggests that physical adsorption reduces the catalytic efficiency; this could explain the large range of values of the catalytic efficiency reported in the literature. The rate of reactions 2.1 increased with increase of temperature; the energy of activation (M = SO2), determined for the first time, is compared with literature values using other third bodies. The importance of the complete exclusion of water from the apparatus and reagents was essential. Unless great precautions are taken, an oily film, possibly of H2SO 4, is formed on the walls of the reactor; this has a pronounced catalytic effect on the reaction. The mechanism of this reaction is discussed in terms of the attainment of a steady state concentration of SO3.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Physical Chemistry