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===Sublimation===
[[File:co2 dry ice.PNG|400px|thumbnail|right|framed|Figure 1: A piece of solid carbon dioxide (dry ice) sublimating from a solid directly into a gas.<ref name=thoughtco>Helmenstine, Anne Marie, Ph.D. "Sublimation Definition (Phase Transition in Chemistry)," ThoughtCo, Feb. 16, 2021. [Online]. Available: thoughtco.com/definition-of-sublimation-phase-transition-604665. [Accessed: 12-May-2021]</ref>]]

<onlyinclude>'''Sublimation''' is a type of [[phase change]] that takes place when a [[solid]] turns directly into a [[gas]], skipping the [[liquid]] phase. The opposite of sublimation is '''vapour deposition'''.</onlyinclude> The term "sublimation" only applies to a physical change of state and not to the transformation of a solid into a gas during a chemical reaction.<ref name=usgs/>

One common example of sublimation is solid [[carbon dioxide]], known as dry ice. At room temperature (293 K) and pressure (1.01 [[Bar]]), dry ice sublimates into carbon dioxide vapor. Sublimation is an [[endothermic]] process that happens below a substance's '''triple point''' in its phase diagram.<ref>"Sublimation (physics)," World Heritage Encyclopedia. [Online]. Available: http://self.gutenberg.org/articles/Sublimation_(physics). [Accessed: 14-May-2021]</ref> Figure 2 shows a phase diagram for carbon dioxide where sublimation would occur below the triple point (216.55 K and 5.17 Bar).<ref>"Phases of matter," UCSB Physics. [Online]. Available: http://web.physics.ucsb.edu/~lecturedemonstrations/Composer/Pages/48.36.html. [Accessed: 12-May-2021]</ref> This means that liquid carbon dioxide is possible, it just requires 5 times normal [[atmospheric pressure]] in order to get the liquid to form. The [[temperature]]s and [[pressure]]s under which sublimation happens depends on the chemical and physical properties of the system. The [[energy]] associated with a transition from solid directly to gas is called the [[latent heat]] of sublimation.

Sublimation also happens with [[snow]]. This means that when the air is particular dry (low [[humidity]]) the water turns directly from snow or ice into water vapour without being liquid at all.<ref name=usgs>"Sublimation and the water cycle", USGS [Online]. Available: https://www.usgs.gov/special-topic/water-science-school/science/sublimation-and-water-cycle?qt-science_center_objects=0#qt-science_center_objects [Accessed: May 13th, 2021.]</ref>

[[File:triple point of CO2.PNG|600px|thumbnail|center|framed|Figure 2: Phase diagram of [[carbon dioxide]] showing how sublimation happens below the triple point.<ref>"Supercritical carbon dioxide," Wikipedia, 2021. [Online]. Available: https://en.wikipedia.org/wiki/Supercritical_carbon_dioxide. [Accessed: 12-May-2021]</ref> Higher pressures would make the dry ice look 'wet', since liquid carbon dioxide would form.]]

Visit UC Davis' [https://chem.libretexts.org/@go/page/95737 Chem wiki] for more information on sublimation.

===Deposition===
As stated earlier, vapour deposition is the opposite of [[sublimation]]. Deposition is when a substance in [[gas]] form changes states to become a [[solid]]. The gaseous substance gets '''deposited''' (usually as crystals) bypassing the intermediate [[liquid]] state. An example of deposition is when water vapor in the [[atmosphere]] changes directly into ice, such as the formation of frost.<ref name=usgs/>

==For Further Reading==
*[[Solid]], [[liquid]], [[Gas]]
*[[Latent heat]]
*[[Specific latent heat]]
*[[Phase change]]
*Or explore a [[Special:Random|random page]]

==References==
{{reflist}}
[[Category:Uploaded]]

Sublimation and deposition - Revision history

Jmdonev: 1 revision imported

energy>Jmdonev at 22:42, 25 May 2021