Model Computation of Water Clustering (H2o)N Effect in the Negative Ion Proton Transfer Reactions

Degaga, Gemechis Dereje (2010) Model Computation of Water Clustering (H2o)N Effect in the Negative Ion Proton Transfer Reactions. Masters thesis, Addis Ababa University.

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Abstract

We report the effect of water clustering (H2O) n in the negative ion proton transfer reactions on reaction rate constants and the change in the Gibbs free energy of the corresponding reactions. Reaction rate constant of the reaction between the new proposed reagent acetate ion CH3COO- than the usual hydronium H3O+ and environmentally important molecules were computed. The computation was made using the hard sphere average dipole orientation theory (HSA) and the average dipole orientation theory (ADO) as an investigation tool. It was found that rate constant decreases for a range of cluster size and starts to below up steadily for the HSA. For ADO, it decreases approaching a lower limiting value. Rate constant were observed to rise as molecular size in enlarges and became non-sensitive to isomers of the same molecule for molecules which have similar dipole moments but different molecular size and structural configuration. Fifteen atmospherically potential molecules were chosen in the study scheme of the effect of the clustering to the reagent ion on the proton transfer reaction rate constant and the change in Gibbs free energy of these reactions. In both cases of the theories, the computed results of the rate constants of the clustered reagent ion were found to be less than that of the non-clustered. In contrary to this, change in the Gibbs free energy of the reactions was found to be greater. The rate constant of the reaction between clustered ions of these molecules and the neutral acetic acid molecule was also computed. These computed results facilitate the use of NI-PTR MS technique, which uses acetate ion as reagent ion, in the application of laboratory investigations and field measurement of environmentally important volatile organic compounds VOCs.

Item Type:	Thesis (Masters)
Subjects:	G Geography. Anthropology. Recreation > GE Environmental Sciences Q Science > Q Science (General) Q Science > QD Chemistry
Divisions:	Africana
Depositing User:	Selom Ghislain
Date Deposited:	25 May 2018 13:06
Last Modified:	25 May 2018 13:06
URI:	http://thesisbank.jhia.ac.ke/id/eprint/4114

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