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In thermodynamics, the enthalpy of sublimation, or heat of sublimation, is the heat required to sublimate (change from solid to gas) one mole of a substance at a given combination of temperature and pressure, usually standard temperature and pressure (STP). It is equal to the cohesive energy of the solid.
Sublimation is caused by the absorption of heat which provides enough energy for some molecules to overcome the attractive forces of their neighbors and escape into the vapor phase. Since the process requires additional energy, sublimation is an endothermic change.
J.A. Dean (ed.), Lange's Handbook of Chemistry (15th Edition), McGraw-Hill, 1999; Section 6, Thermodynamic Properties; Table 6.4, Heats of Fusion, Vaporization, and Sublimation and Specific Heat at Various Temperatures of the Elements and Inorganic Compounds
Enthalpy change of sublimation at 273.15 K, Δ sub H: 51.1 kJ/mol Std entropy change of sublimation at 273.15 K, 1 bar, Δ sub S ~144 J/(mol·K) Molal freezing point constant: −1.858 °C kg/mol Molal boiling point constant: 0.512 °C kg/mol Solid properties Std enthalpy change of formation, Δ f H o solid: −291.83 kJ/mol Standard molar ...
J.A. Dean (ed), Lange's Handbook of Chemistry (15th Edition), McGraw-Hill, 1999; Section 6, Thermodynamic Properties; Table 6.4, Heats of Fusion, Vaporization, and Sublimation and Specific Heat at Various Temperatures of the Elements and Inorganic Compounds
Enthalpy of fusion or melting. This applies to the transition of a solid to a liquid and is designated ΔH m. Enthalpy of vaporization. This applies to the transition of a liquid to a vapor and is designated ΔH v. Enthalpy of sublimation. This applies to the transition of a solid to a vapor and is designated ΔH s.
For 0 < α < 1, the heat capacity diverges at the transition temperature (though, since α < 1, the enthalpy stays finite). An example of such behavior is the 3D ferromagnetic phase transition. In the three-dimensional Ising model for uniaxial magnets, detailed theoretical studies have yielded the exponent α ≈ +0.110.
V is the enthalpy of sublimation for metal atoms (lithium) B is the bond enthalpy (of F 2 ). The coefficient 1/2 is used because the formation reaction is Li + 1/2 F 2 → LiF.