Papers by Keyword: Chemical Reaction Equilibrium

Abstract: The rate of transformation of ozone in the troposphere over a temperature range of-100°C and +100°C has been established. Tropospheric ozone with the quality of a strong oxidizing agent, is secondary pollutant species associated with the initiation of numerous chemical reactions in the atmosphere. In this study, a theoretical approach utilized Gibb’s free energy of reaction and enthalpy of reaction in transition state theory model equations to generate chemical equilibrium data and consequently reaction kinetic parameters. The thermochemical properties were obtained using electronic structural methods of the quantum mechanics computational chemistries which approximates the Schrödinger equation. The model chemistry methods were evaluated using the GuassView for generating molecular structures of species and the Gaussian 03 (G03) package for energy computation. The study revealed that the most relevant of the reactions considered was that involving NO with a rate constant of 7.39 x 10¹¹ s^-1 and energy of activation (E_A/R) of-216.98 K while the least involved HS* with rate constant of 9.56 x 10⁶⁹ s^-1 and energy of activation (E_A/R) of-202.95 K.

Abstract: 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.