Heat of Fusion

(redirected from Enthalpy of fusion)
Also found in: Dictionary, Thesaurus, Medical, Wikipedia.
Related to Enthalpy of fusion: heat of fusion, Enthalpy of vaporization, Enthalpy of sublimation

heat of fusion

[′hēt əv ′fyü·zhən]
(thermodynamics)
The increase in enthalpy accompanying the conversion of 1 mole, or a unit mass, of a solid to a liquid at its melting point at constant pressure and temperature. Also known as latent heat of fusion.

Heat of Fusion

 

(or latent heat of fusion), the amount of heat that must be supplied to a substance in an equilibrium constant-pressure and constant-temperature process to convert the substance from the solid (crystalline) state to the liquid state. The same amount of heat is liberated when the substance crystallizes.

The heat of fusion is a special case of the heat of a first-order transition. For a given substance, the heat of fusion may be determined per unit mass or per mole. In the former case, the heat of fusion is measured in, for example, joules per kg (J/kg) or kilocalories

Table 1. Heat of fusion of several substances
Substancetm(°C)Lf(kcal/kg)Lf(J/kg)
Hydrogen ...............–259.113.8958,200
Nitrogen ...............–209.866.0925,500
Mercury ...............–38.892.8211,800
Ice ...............079.4333,000
Tin ...............231.914.460,300
Lead ...............327.45.8924,700
Copper ...............108348.9205,000
Iron ...............153965272,000

per kg (kcal/kg). In the latter case, the heat of fusion may be expressed in joules per mole. The term “molar heat of fusion” is sometimes applied to the heat of fusion per mole. Table 1 gives the values of the heat of fusion per kg Lf for several substances at atmospheric pressure (760 mm Hg, or 101,325 newtons per m2) and at the melting point tm.

References in periodicals archive ?
in the case of PP-T-I or PP-AM-T-1, where the correction factor lCt ) ) was applied to calculate the enthalpy of fusion, the values of crystallinity obtained from both techniques are very close to each other.
A TA instruments DSC2010 was used to measure the enthalpy of fusion and the melting temperature of samples taken from selected positions through the wall thickness of the various pipes.
samaple] is the enthalpy of fusion for the PHB samples and [DELTA]H* is the enthalpy of fusion for a 100% crystalline PHB, which is 149.
o], the equilibrium enthalpy of fusion, [rho]the specific mass of the polymer, H the Henry's constant, and P the system pressure.
where, [DELTA]h was the enthalpy of fusion per gram of the sample recalculated on iPP mass and [DELTA][h.
MPU-6 exhibited two crystal morphology of which the temperature and the enthalpy of fusion ([DELTA][H.