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Since the heat of combustion of these elements is known, the heating value can be calculated using Dulong's Formula: HHV [kJ/g]= 33.87m C + 122.3(m H - m O ÷ 8) + 9.4m S. where m C, m H, m O, m N, and m S are the contents of carbon, hydrogen, oxygen, nitrogen, and sulfur on any (wet, dry or ash free) basis, respectively. [8]
{{Chembox Thermochemistry}} Header reference Specific heat capacity Standard molar entropy Standard enthalpy change of formation Gibbs free energy Standard enthalpy change of combustion Heat of combustion#Higher heating value Heat of combustion#Lower heating value
Thermodynamic data is usually presented as a table or chart of function values for one mole of a substance (or in the case of the steam tables, one kg). A thermodynamic datafile is a set of equation parameters from which the numerical data values can be calculated.
Standard enthalpy of combustion is the enthalpy change when one mole of an organic compound reacts with molecular oxygen (O 2) to form carbon dioxide and liquid water. For example, the standard enthalpy of combustion of ethane gas refers to the reaction C 2 H 6 (g) + (7/2) O 2 (g) → 2 CO 2 (g) + 3 H 2 O (l).
For instance, carbon and hydrogen will not directly react to form methane (CH 4), so that the standard enthalpy of formation cannot be measured directly. However the standard enthalpy of combustion is readily measurable using bomb calorimetry. The standard enthalpy of formation is then determined using Hess's law. The combustion of methane:
Std enthalpy change of formation, Δ f H o liquid? kJ/mol Standard molar entropy, S o liquid: 117.8 J/(mol K) Heat capacity, c p: 67.4 J/(mol K) Gas properties Std enthalpy change of formation, Δ f H o gas +52.47 kJ/mol Standard molar entropy, S o gas: 219.32 J/(mol K) Enthalpy of combustion, Δ c H o –1387.4 kJ/mol Heat capacity, c p: 42.9 ...
The subject commonly includes calculations of such quantities as heat capacity, heat of combustion, heat of formation, enthalpy, entropy, and free energy. The world's first ice-calorimeter , used in the winter of 1782–83, by Antoine Lavoisier and Pierre-Simon Laplace , to determine the heat evolved in various chemical changes ; calculations ...
Std enthalpy change of formation, Δ f H o liquid –198.7 kJ/mol Standard molar entropy, S o liquid: 295 J/(mol K) Enthalpy of combustion, Δ c H o –4163 kJ/mol Heat capacity, c p: 197.66 J/(mol K) Gas properties Std enthalpy change of formation, Δ f H o gas –167.2 kJ/mol Standard molar entropy, S o gas: 388.82 J/(mol K) Heat capacity, c ...