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Chapter 15 - Chemical reactions. The objectives of Chapter 15 are to: Give an overview of fuels and combustion; apply the conservation of mass to reacting systems to determine balanced reaction equations; define the parameters used in combustion analysis, such as air–fuel ratio, percent theoretical air, and dew-point temperature;. | Chapter 15 Chemical Reactions Study Guide in PowerPoint to accompany Thermodynamics: An Engineering Approach, 8th edition by Yunus A. Çengel and Michael A. Boles The combustion process is a chemical reaction whereby fuel is oxidized and energy is released. Fuels are usually composed of some compound or mixture containing carbon, C, and hydrogen, H2. Examples of hydrocarbon fuels are CH4 Methane C8H18 Octane Coal Mixture of C, H2, S, O2, N2 and non-combustibles Initially, we shall consider only those reactions that go to completion. The components prior to the reaction are called reactants and the components after the reaction are called products. For complete or stoichiometric combustion, all carbon is burned to carbon dioxide (CO2) and all hydrogen is converted into water (H2O). These two complete combustion reactions are as follows: Example 15-1 A complete combustion of octane in oxygen is represented by the balanced combustion equation. The balanced . | Chapter 15 Chemical Reactions Study Guide in PowerPoint to accompany Thermodynamics: An Engineering Approach, 8th edition by Yunus A. Çengel and Michael A. Boles The combustion process is a chemical reaction whereby fuel is oxidized and energy is released. Fuels are usually composed of some compound or mixture containing carbon, C, and hydrogen, H2. Examples of hydrocarbon fuels are CH4 Methane C8H18 Octane Coal Mixture of C, H2, S, O2, N2 and non-combustibles Initially, we shall consider only those reactions that go to completion. The components prior to the reaction are called reactants and the components after the reaction are called products. For complete or stoichiometric combustion, all carbon is burned to carbon dioxide (CO2) and all hydrogen is converted into water (H2O). These two complete combustion reactions are as follows: Example 15-1 A complete combustion of octane in oxygen is represented by the balanced combustion equation. The balanced combustion equation is obtained by making sure we have the same number of atoms of each element on both sides of the equation. That is, we make sure the mass is conserved. Note we often can balance the C and H for complete combustion by inspection. The amount of oxygen is found from the oxygen balance. It is better to conserve species on a monatomic basis as shown for the oxygen balance. Note: Mole numbers are not conserved, but we have conserved the mass on a total basis as well as a specie basis. Also, 12.5 kmol of O2 are used to form the CO2 and H2O. If 15 kmol of O2 were supplied to the process, 2.5 kmol of O2 would be excess oxygen in the products. The complete combustion process is also called the stoichiometric combustion, and all coefficients are called the stoichiometric coefficients. In most combustion processes, oxygen is supplied in the form of air rather than pure oxygen. Air is assumed to be 21 percent oxygen and 79 percent nitrogen on a volume basis. For .
