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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.
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).
The formula that yields this temperature is based on the first law of thermodynamics and takes note of the fact that the heat of combustion is used entirely for heating the fuel, the combustion air or oxygen, and the combustion product gases (commonly referred to as the flue gas).
Enthalpy (/ ˈ ɛ n θ əl p i / ⓘ) is the sum of a thermodynamic system's internal energy and the product of its pressure and volume. [1] It is a state function in thermodynamics used in many measurements in chemical, biological, and physical systems at a constant external pressure, which is conveniently provided by the large ambient atmosphere.
For many substances, the formation reaction may be considered as the sum of a number of simpler reactions, either real or fictitious. The enthalpy of reaction can then be analyzed by applying Hess' law, which states that the sum of the enthalpy changes for a number of individual reaction steps equals the enthalpy change of the overall reaction.
Uses Antoine's equation: = + from Lange's Handbook of Chemistry 10th ed. Here is a similar formula from the 67th edition of the CRC handbook. Note that the form of this formula as given is a fit to the Clausius–Clapeyron equation, which is a good theoretical starting point for calculating saturation vapor pressures:
Heat capacity, c p: 111.46 J/(mol K) [5] Liquid properties Std enthalpy change of formation, Δ f H o liquid: −277.38 kJ/mol Standard molar entropy, S o liquid: 159.9 J/(mol K) Enthalpy of combustion, Δ c H o: −1370.7 kJ/mol Heat capacity, c p: 112.4 J/(mol K) Gas properties Std enthalpy change of formation, Δ f H o gas: −235.3 kJ/mol ...
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 ...