melting adj : becoming liquid [syn: liquescent] n : the process whereby heat changes something from a solid to a liquid; "the power failure caused a refrigerator melt that was a disaster"; "the thawing of a frozen turkey takes several hours" [syn: thaw, melt, thawing]
- Rhymes: -ɛltɪŋ
- present participle of melt
process of changing the state of a substance
Melting is a process that results in the phase change of a substance from a solid to a liquid. The internal energy of a solid substance is increased (typically by the application of heat) to a specific temperature (called the melting point) at which it changes to the liquid phase. An object that has melted completely is molten.
The melting point of a substance is a characteristic property. The melting point may not be equal to the freezing point. This is evident in the phenomenon known as supercooling. In the case of water, ice crystals typically require a seed on which to begin formation. Water on a very clean glass surface will often supercool several degrees below the melting point without freezing. Fine emulsions of pure water have been cooled to -38 degrees celsius without the nucleation of ice taking place. For this reason, melting point is a characteristic property of a substance while freezing point is not.
Molecular vibrationsWhen the internal energy of a gas is increased by the application of an external energy source, the molecular vibrations of the substance increases. As these vibrations increase, the substance becomes more and more ordered. Fusion is also another term used for this.
Constant temperatureSubstances melt at a constant temperature, the melting point. Further increases in temperature (even with continued application of energy) do not occur until the substance is molten.
The thermodynamics of meltingFrom a thermodynamics point of view, at the melting point the change in Gibbs free energy (\Delta G) of the Material is zero, because the enthalpy (H) and the entropy (S) of the material are increasing (\Delta H, \Delta S > 0). Melting phenomenon happens when the Gibbs free energy of the liquid becomes lower than the solid for that material. At various pressures this happens at a specific temperature. It can also be shown that:
\Delta S = \frac
The "T","\Delta S", and "\Delta H" in the above are respectively the temperature at the melting point, change of entropy of melting, and the change of enthalpy of melting.
Other meaningsIn genetics, melting DNA means to separate the double-stranded DNA into two single strands by heating or the use of chemicals.
- See also : Polymerase chain reaction
melting in Bulgarian: Топене
melting in Catalan: Fusió (canvi d'estat)
melting in Czech: Tání
melting in Danish: Smeltning
melting in German: Schmelzen
melting in Estonian: Sulamine
melting in Modern Greek (1453-): Τήξη
melting in Spanish: Fusión (cambio de estado)
melting in Basque: Urtze
melting in Persian: ذوب
melting in French: Fusion (physique)
melting in Italian: Fusione (fisica)
melting in Hebrew: התכה
melting in Latvian: Kušana
melting in Lithuanian: Lydymasis
melting in Dutch: Smelten (faseovergang)
melting in Japanese: 融解
melting in Low German: Smölten
melting in Polish: Topnienie
melting in Portuguese: Fusão
melting in Russian: Плавление
melting in Simple English: Melting
melting in Slovak: Topenie
melting in Slovenian: Taljenje
melting in Finnish: Sulaminen
melting in Swedish: Smältning
melting in Tamil: உருகுதல்
melting in Turkish: Erime
melting in Ukrainian: Плавлення
melting in Chinese: 融化
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