FREEZING

:''For freezing as a method of food preservation, see frozen food.''
In physics and chemistry, 'freezing' is the process whereby a liquid turns to a solid. The freezing point is the temperature at which this happens. Melting, the process of turning a solid to a liquid, is the opposite of freezing. For most substances, the melting and freezing points are the same temperature.
Rapid cooling by exposure to cryogenic temperatures can cause a substance to freeze below its melting point, a process known as flash freezing. For some pure substances, such as pure water, the freezing temperature is lower than the melting temperature. The freezing point for water is only the same temperature as the melting point when nucleators are present to prevent supercooling. The freezing point of water is 0°C (32°F, 273 K). In the absence of nucleators water will supercool to as low as −70°C (−94°F, 203 K) before freezing. ^[1] But in the presence of nucleating substances the freezing point of water is the same as the melting point. Nucleating agents, such as dust, are commonly present in the environment, which is why rain water and tap water will normally freeze at the melting point of water.

Contents

Food preservation

References

See also

External links

Food preservation

Main articles: Frozen food

Freezing is a common method of food preservation which slows both food decay and the growth of micro-organisms. Besides the effect of lower temperatures on reaction rates, freezing makes water less available for bacterial growth. there are many forms of freezing see below for details

References

1.

See also

★ Flash freezing

★ Nucleation

★ Supercooling

★ Melting point

★ Frost

External links

★ Freezing of water, an enigma
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'From'	'To'
	Solid	Liquid	Gas	Plasma
Solid	Solid-Solid Transformation	Melting	Sublimation	-
Liquid	Freezing	N/A	Boiling/Evaporation	-
Gas	Deposition	Condensation	N/A	Ionization
Plasma	-	-	Recombination/Deionization	N/A