Explore chapters and articles related to this topic
The first law
Published in W. John Rankin, Chemical Thermodynamics, 2019
where A and B are elements which react to form the compound AkBl. The standard enthalpy of formationΔfH0 of a compound is defined as the change in enthalpy when 1 mole of the compound is formed from its constituent elements under standard state conditions at a specified temperature; that is,
Thermodynamics of Fuel Cells
Published in Xianguo Li, Principles of Fuel Cells, 2005
The enthalpy of formation can be determined by laboratory measurements or by advanced methods of statistical thermochemistry. In laboratory measurements, the standard enthalpy of formation, hf,io(25°C), for a given substance is equal to the amount of heat absorbed or released when one mole of the substance is formed from its elemental substances in their standard reference state, for example, C(s)+O2(g)→CO2−393,522J/mol
Basic Chemical Thermodynamics and Kinetics
Published in Kalliat T. Valsaraj, Elizabeth M. Melvin, Principles of Environmental Thermodynamics and Kinetics, 2018
Kalliat T. Valsaraj, Elizabeth M. Melvin
There are three important enthalpy terms that merit discussion. These are “standard enthalpy of reaction” (ΔHro), “standard enthalpy of formation” (ΔHfo), and “standard enthalpy of combustion” (ΔHco). The standard enthalpy of reaction is the enthalpy change for a system during a chemical reaction and is the sum of the standard enthalpy of formation of the products minus the sum of the standard enthalpy of formation of the reactants. The standard enthalpy of formation is the enthalpy change to produce 1 mol of the compound from its elements, all at standard conditions. The standards enthalpies of reaction may be combined in various ways. This is succinctly expressed in the “Hess’s law of heat summation: The standard enthalpy of a reaction is the sum of the standard enthalpies of reactions into which an overall reaction may be divided, and holds true if the referenced temperatures of each individual reaction are the same.” The standard enthalpy of combustion is that required to burn or oxidize 1 mol of the material to a final state that contains only H2O (l) and CO2.
Flow and heat transfer of hydrocarbon fuel in the double-layer regenerative cooling channels
Published in Numerical Heat Transfer, Part A: Applications, 2023
Yuguang Jiang, Leqing Wang, Qilin Zhou, Nicolas Gascoin, Khaled Chetehouna, Wei Fan
Standard enthalpy of formation is used to describe the energy variation caused by chemical reaction. The energy conservation equation can be presented in Eq. (3) without the energy source term. Considering the relatively low flow velocity in this work, the term related to viscous dissipation is neglected.