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By convention, the (higher) heat of combustion is defined to be the heat released for the complete combustion of a compound in its standard state to form stable products in their standard states: hydrogen is converted to water (in its liquid state), carbon is converted to carbon dioxide gas, and nitrogen is converted to nitrogen gas.
The combustion of ethane releases 1559.7 kJ/mol, or 51.9 kJ/g, of heat, and produces carbon dioxide and water according to the chemical equation: 2 C 2 H 6 + 7 O 2 → 4 CO 2 + 6 H 2 O + 3120 kJ. Combustion may also occur without an excess of oxygen, yielding carbon monoxide, acetaldehyde, methane, methanol, and ethanol.
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).
Water: Gas H 2 O −241.818 Water: Liquid H 2 O −285.8 Hydrogen ion: Aqueous H + 0 Hydroxide ion: Aqueous OH −: −230 Hydrogen peroxide: Liquid H 2 O 2: −187.8 Phosphoric acid: Liquid H 3 PO 4: −1288 Hydrogen cyanide: Gas HCN 130.5 Hydrogen bromide: Liquid HBr −36.3 Hydrogen chloride: Gas HCl −92.30 Hydrogen chloride: Aqueous HCl ...
Note that the especially high molar values, as for paraffin, gasoline, water and ammonia, result from calculating specific heats in terms of moles of molecules. If specific heat is expressed per mole of atoms for these substances, none of the constant-volume values exceed, to any large extent, the theoretical Dulong–Petit limit of 25 J⋅mol ...
Heat capacity, c p? J/(mol K) Liquid properties Std enthalpy change of formation, Δ f H o liquid? kJ/mol Standard molar entropy, S o liquid: 126.7 J/(mol K) Heat capacity, c p: 68.5 J/(mol K) at −179 °C Gas properties Std enthalpy change of formation, Δ f H o gas: −83.8 kJ/mol Standard molar entropy, S o gas: 229.6 J/(mol K) Enthalpy of ...
It also happens when the combustion is quenched by a heat sink, such as a solid surface or flame trap. As is the case with complete combustion, water is produced by incomplete combustion; however, carbon and carbon monoxide are produced instead of carbon dioxide. For most fuels, such as diesel oil, coal, or wood, pyrolysis occurs before ...
Temperature-dependency of the heats of vaporization for water, methanol, benzene, and acetone. In thermodynamics, the enthalpy of vaporization (symbol ∆H vap), also known as the (latent) heat of vaporization or heat of evaporation, is the amount of energy that must be added to a liquid substance to transform a quantity of that substance into a gas.