Sublimation (phase transition): Difference between revisions

Revision as of 06:53, 2 November 2022

Revision as of 10:33, 8 November 2022

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[[File:Nickelocen an einem Kühlfinger.jpg|thumb|right|Dark green [[crystals]] of [[nickelocene]], sublimed and freshly deposited on a [[cold finger]]]]

'''Sublimation''' is the [[Phase transition|transition of a substance]] directly from the [[solid]] to the [[gas]] state,<ref>{{cite Merriam-Webster|Sublimate}}</ref> without passing through the liquid state.<ref>{{cite book |last1=Whitten |first1=Kenneth W. |last2=Gailey |first2=Kenneth D. |last3=Davis |first3=Raymond E. |title=General chemistry |url=https://archive.org/details/generalchemistry00whit_0 |url-access=registration |date=1992 |publisher=Saunders College Publishing |isbn=0-03-072373-6 |page=[https://archive.org/details/generalchemistry00whit_0/page/475 475] |edition=4th}}</ref> Sublimation is an [[endothermic process]] that occurs at temperatures and pressures below a substance's [[triple point]] in its [[phase diagram]], which corresponds to the lowest pressure at which the substance can exist as a liquid. The reverse process of sublimation is [[deposition (phase transition)|deposition]] or desublimation, in which a substance passes directly from a gas to a solid phase.<ref name="DepositionDef">{{cite journal |title=Controlling condensation and frost growth with chemical micropatterns |first1=Jonathan B. |last1=Boreyko |first2=Ryan R. |last2=Hansen |first3=Kevin R. |last3=Murphy |first4=Saurabh |last4=Nath |first5=Scott T. |last5=Retterer |first6=C. Patrick |last6=Collier |journal=Scientific Reports |year=2016 |volume=6 |pages=19131 |doi=10.1038/srep19131 |pmid=26796663 |pmc=4726256 |bibcode=2016NatSR...619131B}}</ref> Sublimation has also been used as a generic term to describe a solid-to-gas transition (sublimation) followed by a gas-to-solid transition ([[deposition (phase transition)|deposition]]).<ref>{{Dictionary.com|Sublime}}</ref> While [[vaporization]] from liquid to gas occurs as [[evaporation]] from the surface if it occurs below the boiling point of the liquid, and as [[boiling]] with formation of bubbles in the interior of the liquid if it occurs at the boiling point, there is no such distinction for the solid-to-gas transition which always occurs as sublimation from the surface.

At [[standard conditions for temperature and pressure|normal pressures]], most [[chemical compound]]s and [[chemical element|elements]] possess three different states at different [[temperature]]s. In these cases, the transition from the solid to the [[gaseous state]] requires an intermediate liquid state. The pressure referred to is the ''[[partial pressure]]'' of the substance, not the ''total'' (e.g. atmospheric) pressure of the entire system. So, all solids that possess an appreciable [[vapour pressure]] at a certain temperature usually can sublime in air (e.g. water ice just below 0&nbsp;°C). For some substances, such as [[carbon]] and [[arsenic]], sublimation is much easier than [[evaporation]] from the melt, because the pressure of their [[triple point]] is very high, and it is difficult to obtain them as liquids.