Evaluation of the thermochemical properties for tropospheric ozone reactions
International Journal of Engineering Research in Africa
Air Pollution Climatology and Energy Research Group, Department of Chemical Engineering, University of Benin, Benin City, Nigeria
The thermochemical properties of varieties of species involved in the formation and consumption or destruction of tropospheric ozone during chemical reactions have been established. Ozone in the troposphere is produced during the day-time; hence it is a photochemically induced transformation process. This compound acts as precursor specie in many atmospheric transformations and constitutes a baseline component worth investigating. This study utilized electronic structure methods of computational model chemistries to evaluate for Gibbs free energies and enthalpies of formation and reactions of the various species. Ten prominent gas-phase and aqueous-phase reactions were analysed using five computational approaches consisting of four ab initio methods and one density functional theory (DFT) method. The computed energy values in comparison to those obtained through experimental approaches yielded an error of mean absolute deviation of 0.81%. The most relevant species that tend to enhance the production of ozone in the troposphere were O* and H2O2 for the gas-phase and aqueous-phase reactions respectively. Chemical equilibrium analysis indicated that the ozone formation and consumption reactions are more favourable in colder regions and at winter. © (2010) Trans Tech Publications, Switzerland.
Ab initio method; Atmospheric transformation; Chemical equilibriums; Chemical reaction equilibrium; Computational approach; Computational model; Density functional theory methods; Energy value; Enthalpies of formation; Experimental approaches; Gasphase; Mean absolute deviations; Ozone formation; Thermochemical properties; Transformation process; Tropospheric ozone; Chemical reactions; Computational methods; Density functional theory; Electronic structure; Troposphere; Ozone