freezing point

freezing point
Physical Chem.
the temperature at which a liquid freezes: The freezing point of water is 32°F, 0°C.

* * *

Temperature at which a liquid becomes a solid.

When the pressure surrounding the liquid is increased, the freezing point is raised. The addition of some solids can lower the freezing point of a liquid, a principle used when salt is applied to melt ice on frozen surfaces. For pure substances, the freezing point is the same as the melting point. In mixtures and certain organic compounds, the early solid formation changes the composition of the remaining liquid, usually steadily lowering its freezing point, a principle that is applied in mixture separation. The freezing point of pure water at standard atmospheric pressure is 32°F (0°C). To change a liquid at its freezing point to a solid at the same temperature, the heat of fusion (see latent heat) must be removed.

* * *

▪ chemistry and physics
      temperature at which a liquid becomes a solid. As with the melting point, increased pressure usually raises the freezing point. The freezing point is lower than the melting point in the case of mixtures and for certain organic compounds such as fats. As a mixture freezes, the solid that forms first usually has a composition different from that of the liquid, and formation of the solid changes the composition of the remaining liquid, usually in a way that steadily lowers the freezing point. This principle is used in purifying mixtures, successive melting and freezing gradually separating the components. The heat of fusion (see thermal fusion), the heat that must be applied to melt a solid, must be removed from the liquid to freeze it. Some liquids can be supercooled—i.e., cooled below the freezing point—without solid crystals forming. Putting a seed crystal into a supercooled liquid triggers freezing, whereupon the release of the heat of fusion raises the temperature rapidly to the freezing point.

      The addition of one mole (molecular weight in grams) of any non-ionic (does not form ions) solute to 1,000 grams of water lowers the freezing point of the water by 1.885° C, and this has been used as an accurate method for determining molecular weights.

* * *

Universalium. 2010.

Игры ⚽ Поможем написать реферат

Look at other dictionaries:

  • freezing point — freezing points also freezing point 1) N UNCOUNT: usu above/below/to N Freezing point is 0° Celsius, the temperature at which water freezes. Freezing point is often used when talking about the weather. The temperature remained below freezing… …   English dictionary

  • Freezing point — can refer to several things:*Melting point, a term in chemistry referring to the temperature at which a substance in its solid form starts to melt * Freezing Point , a Beijing weekly news journal * Freezing Point (1966 film), a 1966 Japanese film …   Wikipedia

  • Freezing point — Freezing Freez ing, a. Tending to freeze; for freezing; hence, cold or distant in manner. {Frrez ing*ly}, adv. [1913 Webster] {Freezing machine}. See {Ice machine}, under {Ice}. {Freezing mixture}, a mixture (of salt and snow or of chemical… …   The Collaborative International Dictionary of English

  • Freezing Point — (Chinese: 冰點, Bīngdiǎn) [Pinyin translated with [ CozyChinese.COM] ] is a news journal in the People s Republic of China which has been the subject of controversy over its criticism of Communist Party officials… …   Wikipedia

  • freezing point — n the temperature at which a liquid solidifies specif the temperature at which the liquid and solid states of the substance are in equilibrium at atmospheric pressure: MELTING POINT <the freezing point of water is 0° Celsius or 32°… …   Medical dictionary

  • freezing point — freezing .point n 1.) [U] the temperature at which water turns into ice →↑boiling point 2.) [C usually singular] the temperature at which a particular liquid freezes ▪ Alcohol has a lower freezing point than water …   Dictionary of contemporary English

  • freezing point — n. the temperature at which a liquid freezes or becomes solid: the freezing point of water is 32°F or 0°C: cf. MELTING POINT …   English World dictionary

  • Freezing point — Freezing point. См. Точка затвердевания. (Источник: «Металлы и сплавы. Справочник.» Под редакцией Ю.П. Солнцева; НПО Профессионал , НПО Мир и семья ; Санкт Петербург, 2003 г.) …   Словарь металлургических терминов

  • freezing point — freezing ,point noun count the temperature at which a particular liquid freezes …   Usage of the words and phrases in modern English

  • freezing point — ► NOUN ▪ the temperature at which a liquid turns into a solid when cooled …   English terms dictionary

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”