Standard enthalpy fusion

Here, AHfu° is the standard enthalpy of fusion and T, is the melting point. All entropies of fusion are positive, and so they are normally reported without their positive sign. 

Figure 1.3 Standard enthalpy of aluminium relative to 0 K. The standard enthalpy of fusion (Afugffm) is significantly smaller than the standard enthalpy of vaporization (A vap// ).

The types of values reported in the database standard enthalpies of formation at 298.15 K and 0 K, bond dissociation energies or enthalpies (D) at any temperature, standard enthalpy of phase transition—fusion, vaporization, or sublimation—at 298.15 K, standard entropy at 298.15 K, standard heat capacity at 298.15 K, standard enthalpy differences between T and 298.15 K, proton affinity, ionization energy, appearance energy, and electron affinity. The absence of a check mark indicates that the data are not provided. However, that does not necessarily mean that they cannot be calculated from other quantities tabulated in the database. 

Relationships Between Enthalpy-Entropy of Fusion and Enthalpy-Entropy of Formation of Melt Components at Standard State... 

E° = E°(cathode) — °(anode). standard enthalpy of combustion AHc° The change of enthalpy per mole of substance when it bums (reacts with oxygen) completely under standard conditions, standard enthalpy of formation AH° The standard reaction enthalpy per mole of compound for the compound s synthesis from its elements in their most stable form at 1 atm and the specified temperature, standard entropy of fusion ASfus° The standard entropy change per mole accompanying fusion (the conversion of a substance from the solid state to the liquid state), standard entropy of vaporization ASvap° The standard entropy change per mole accompanying vaporization (the conversion of a substance from the liquid state to the vapor state). 

AfusH° standard enthalpy of fusion per mole (solid - liquid) Afus ... 

Values of dissociation energies were taken with few exceptions from T. L. Cottrell, The Strength of Chemical Bonds , Butterworth, London (1958). Standard enthalpies of formation, heats of fusion and vaporization or heats of sublimation were taken from F. D. Rossini, D. D. Wagman, W. H. Evans, S. Levine and I. Jaffee, "Selected Values of Chemical Thermodynamic Properties , National Bureau of Standards Circular 500 (1952), except for cases where more recent data have been published since. Improved enthalpy data for a number of fluorides and chlorides have been compiled hy H. A. Skinner, Pure and Applied Chemistry 8, 113 (1964). Heats of atomization of the elements were taken from D. R. Stull and G. C. Sinke, Thermodynamic Properties of the Elements , Advances in Chemistry Series No. 18, American Chemical Society, Washington (1956). Enthalpy data for GeBr4 and... 

According to Reichelt and Hemminger (144), the values of the calibration constant of a DSC apparatus obtained by means of heat of fusion standards are different from those of well-known heat capacity standards. Varying the container geometry, they were able to show that there was no influence of the disturbance of steady-state conditions of heat flux on the calculated value of the enthalpy of fusion of indium. An error of 20% in the enthalpy may result if incorrectly closed containers are employed. 

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