Chemical Reactions, First - Law Analysis Of Reacting Systems

M. Bahrami ENSC 461 (S 11) Chemical Reactions 1 ChemicalReactionsWhen analyzing reacting systems, we need to consider the chemical internal energy, which is the energy associated with the destruction and formation of chemical bonds between the atoms. Thermodynamic analysis of reactive mixtures is primarily an extension of the principles we have learned thus far; however, it is necessary to modify the methods used to calculate specific enthalpy, internal energy and entropy. DefinitionsFuel: any material that can be burned to release thermal energy. Most familiar fuels are hydrocarbons and are denoted by the general formula of CnHm. For example octane is C8H18. Combustion: is a chemical reaction during which a fuel is oxidized and a large quantity of energy is released. The oxidizer is often air. Reactants: are the components that exist before the reaction. Products: are the components that exist after the reaction. Ignition temperature: the minimum temperature at which a fuel starts to burn. Dry air is composed of 20.9% O2, 78.1% N2, 0.9% Ar, and small amounts of CO2, He, Ne, H2. In combustion analyses, Ar is treated as N2, and other gases are neglected. Then dry air can be approximated as 21% O2 and 79% N2 by