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HNO3·3H2O [1 record]

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Record 1 2011-03-15

English

Subject field(s)
  • Chemical Elements and Compounds
  • Atmospheric Physics
  • Climate Change
Universal entry(ies)
HNO3·3H2O
formula, see observation
DEF

A stable crystalline form of nitric acid and water, consisting of three molecules of water for every molecule of nitric acid.

CONT

Studies of the Antarctic ozone hole have shown that polar stratospheric clouds (PSCs) play an important role in the depletion of ozone. The PSCs contribute to ozone depletion by cycling chlorine from inactive "reservoir" species such as ClONO2 and HCl into reactive chlorine atoms. Although it is known that one type of PSC particle (Type Ia) contains nitric acid and water in a crystalline form, the composition and formation mechanism of these particles is not yet known. We measured the crystallization rates of nitric acid trihydrate (NAT) and nitric acid dihydrate (NAD) to determine the amount of time which would be required for 3:1 and 2:1 water:nitric acid solutions to freeze to NAT and NAD, respectively, under stratospheric conditions.

OBS

Chemical formula: HNO3·3H2O

French

Domaine(s)
  • Éléments et composés chimiques
  • Physique de l'atmosphère
  • Changements climatiques
Entrée(s) universelle(s)
HNO3·3H2O
formula, see observation
CONT

Lorsque la température en hiver décroît au-dessous d'un seuil, approximativement 195 K, de petites particules solides contenant un mélange d'acide nitrique et d'eau (certainement de l'acide nitrique trihydrate - NAT) se forment et produisent des nuages stratosphériques polaires (polar stratospheric clouds - PSC) dits de type I.

CONT

[...] les PSC [polar stratospheric clouds, en français : nuages stratosphériques polaires] de type Ia [...] sont composés de particules solides de trihydrate d'acide nitrique (acronyme anglais «NAT» signifiant «Nitric Acid Trihydrate») avec une molécule d'acide nitrique pour trois molécules d'eau [...] La température de formation des NAT est typiquement de 5 à 6 degrés supérieure à la température du point de congélation de l'eau, ce qui confère aux PSC Ia une durée de vie plus longue que les PSC II dans l'hémisphère nord.

OBS

Formule chimique : HNO3/3H2O

Spanish

Campo(s) temático(s)
  • Elementos y compuestos químicos
  • Física de la atmósfera
  • Cambio climático
Entrada(s) universal(es)
HNO3·3H2O
formula, see observation
OBS

Fórmula química: HNO3·3H2O

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