Content deleted Content added
No edit summary |
No edit summary Tags: Mobile edit Mobile web edit |
||
| (42 intermediate revisions by 24 users not shown) | |||
Line 1:
{{Short description|Transition
{{Redirect|Sublimates||Sublimation (disambiguation){{!}}Sublimation}}
{{distinguish|subliminal stimuli}}
{{pp|small=yes}}
<!--
READ BEFORE EDIT, sublimation refers to ALL THREE CASES:
1. Sublime gradually: below triple point and left of solid-gas boundary
(similar to evaporation)
(bottom left of solid in phase diagram)
2. Sublime rapidly: below triple point and at solid-gas boundary
(similar to boiling)
3. Sublime gradually: above triple point and left of solid-liquid boundary (yes, solid sublimes above triple point)
(also similar to evaporation, just higher pressure)
(top left of solid in phase diagram)
These three cases jointly exhaust the solid space in the phrase diagram. This makes sense, after all, technically, all solids sublime (depending mostly on vapour pressure, which is very situational).
One may notice there is a fourth case in the solid space, that is, at the solid-liquid boundary. It is uncertain if the solid is still defined as subliming WHILE melting, and in case it is, it would be subliming rapidly.
-->
<!--
checking some online English dictionaries:
1. sublime and sublimate are both valid, and both have some other meanings
https://www.merriam-webster.com/dictionary/sublime#did-you-know
(also almost every dictionary)
2. sublimate may mean the product
https://www.merriam-webster.com/dictionary/sublimate#dictionary-entry-2
https://www.collinsdictionary.com/dictionary/english/sublimate
https://www.dictionary.com/browse/sublimate
https://chambers.co.uk/search/?query=sublimate&title=21st
https://www.wordreference.com/definition/sublimate
3. sublimation may also mean itself followed by deposition
https://www.collinsdictionary.com/dictionary/english/sublime
https://www.dictionary.com/browse/sublime
4. sublimation seems used to mean deposition alone but this meaning is now completely obsolete, few if any online dictionary has such meaning as of 2023, the archaic use is likely phased out
-->
[[File:Nickelocen an einem Kühlfinger.jpg|thumb|right|Dark green [[crystals]] of [[nickelocene]], sublimed and freshly deposited on a [[cold finger]]]]
[[File:Sublimation of iodine.webm|thumb|Sublimation of [[iodine]]]]
'''Sublimation''' is the [[Phase transition|transition of a substance]] directly from the [[solid]] to the [[gas]] state,
The reverse process of sublimation is [[deposition (phase transition)|''deposition'']] (also called ''desublimation''), in which a substance passes directly from a gas to a solid phase, without passing through the liquid state.<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>
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 °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.▼
▲Technically, all solids may sublime, though most sublime at extremely low rates that are hardly detectable under usual conditions. 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 [[
The term ''sublimation'' refers to a [[physical change]] of [[state of matter|state]] and is not used to describe the transformation of a solid to a gas in a chemical reaction. For example, the dissociation on heating of solid [[ammonium chloride]] into hydrogen chloride and ammonia is ''not'' sublimation but a chemical reaction. Similarly the combustion of candles, containing [[paraffin wax]], to [[carbon dioxide]] and [[water vapor]] is ''not'' sublimation but a chemical reaction with oxygen.▼
For some substances, such as [[carbon]] and [[arsenic]], sublimation from solid state is much more achievable than [[evaporation]] from liquid state and it is difficult to obtain them as liquids. This is because the pressure of their [[triple point]] in its [[phase diagram]] (which corresponds to the lowest pressure at which the substance can exist as a liquid) is very high.
Sublimation is caused by the absorption of heat which provides enough energy for some molecules to overcome the [[intermolecular force|attractive forces]] of their neighbors and escape into the vapor phase. Since the process requires additional energy, it is an [[endothermic]] change. The [[enthalpy of sublimation]] (also called heat of sublimation) can be calculated by adding the [[enthalpy of fusion]] and the [[enthalpy of vaporization]].▼
▲Sublimation is caused by the absorption of heat which provides enough energy for some molecules to overcome the [[intermolecular force|attractive forces]] of their neighbors and escape into the vapor phase. Since the process requires additional energy,
[[File:Comparison carbon dioxide water phase diagrams.svg|thumb|upright=2|Comparison of phase diagrams of carbon dioxide (red) and water (blue) showing the carbon dioxide sublimation point (middle-left) at 1 atmosphere. As dry ice is heated, it crosses this point along the bold horizontal line from the solid phase directly into the gaseous phase. Water, on the other hand, passes through a liquid phase at 1 atmosphere.]]▼
== Confusions ==
While the definition of sublimation is simple, there is often confusion as to what counts as a sublimation.
=== False correspondence with vaporization ===
[[Vaporization]] (from liquid to gas) is divided into two types: vaporization on the surface of the liquid is called [[evaporation]], and vaporization at the boiling point with formation of bubbles in the interior of the liquid is called [[boiling]]. However there is ''no'' such distinction for the solid-to-gas transition, which is always called sublimation in both corresponding cases.
==== Potential distinction ====
For clarification, a distinction between the two corresponding cases is needed. With reference to a [[phase diagram]], the sublimation that occurs left of the solid-gas boundary, the triple point or the solid-liquid boundary (corresponding to evaporation in vaporization) may be called ''gradual sublimation''; and the substance ''sublimes gradually'', regardless of rate. The sublimation that occurs at the solid-gas boundary (critical sublimation point) (corresponding to boiling in vaporization) may be called ''rapid sublimation'', and the substance ''sublimes rapidly''. The words "gradual" and "rapid" have acquired special meanings in this context and no longer describe the rate of sublimation.{{cn|date=April 2024}}<!-- This distinction is used only on this page and nowhere else, to minimize confusion. If there is a better distinction, change it along with the examples. If this violates the policy of Wikipedia, please delete this paragraph, and if possible, also provide a better solution. -->
=== Misuse for chemical reaction ===
▲The term ''sublimation'' refers specifically to a [[physical change]] of [[state of matter|state]] and is not used to describe the transformation of a solid to a gas in a chemical reaction. For example, the dissociation on heating of solid [[ammonium chloride]] into hydrogen chloride and ammonia is ''not'' sublimation but a chemical reaction. Similarly the combustion of candles, containing [[paraffin wax]], to [[carbon dioxide]] and [[water vapor]] is ''not'' sublimation but a chemical reaction with oxygen.
=== Historical definition ===
Sublimation is historically used as a generic term to describe a two-step phase transition ― a solid-to-gas transition (sublimation in a more precise definition) followed by a gas-to-solid transition ([[deposition (phase transition)|deposition]]).<ref>{{Dictionary.com|Sublime}}</ref><ref>[https://www.collinsdictionary.com/dictionary/english/sublime "Sublime"]. [[Collins English Dictionary#CollinsDictionary.com|CollinsDictionary.com Dictionary]].</ref> (See [[#Historical usage|below]])
==Examples==
▲[[File:Comparison carbon dioxide water phase diagrams.svg|thumb|upright=2|Comparison of phase diagrams of carbon dioxide (red) and water (blue) showing the carbon dioxide sublimation point (middle-left) at 1 atmosphere. As dry ice is heated, it crosses this point along the bold horizontal line from the solid phase directly into the gaseous phase. Water, on the other hand, passes through a liquid phase at 1 atmosphere.]]
The examples shown are substances that noticeably sublime under certain conditions.
===Carbon dioxide===
[[File:Dry Ice Vapor (17490553041).jpg|thumb|[[Dry ice]] subliming in air]]
Solid [[carbon dioxide]] ([[dry ice]]) sublimes
===Water===
[[Snow]] and [[ice]] sublime
===Naphthalene===
[[File:Sublimation reaction of naphthalene.jpg|thumb|Experimental set up for the sublimation reaction of [[naphthalene]],
[[Naphthalene]], an organic compound commonly found in pesticides such as [[mothball]]s, sublimes easily because it is made of non-polar molecules that are held together only by [[Van der Waals force|van der Waals]] intermolecular forces. Naphthalene is a solid that sublimes at [[standard conditions for temperature and pressure|standard atmospheric temperature]]<ref>▼
[[File:Crystal-like sublimated naphthalene.jpg|thumb|Solid compound of [[naphthalene]] sublimed to form a crystal-like structure on the cool surface.]]▼
▲[[Naphthalene]], an organic compound commonly found in pesticides such as [[mothball]]s, sublimes easily because it is made of non-polar molecules that are held together only by [[Van der Waals force|van der Waals]] intermolecular forces. Naphthalene is a solid that sublimes gradually at [[standard
{{cite book
|last=Caroll |first=J.
Line 30 ⟶ 83:
|isbn=9780128005750
|page=16
|publisher=Gulf Professional
}}</ref> at a high rate, with the critical sublimation point at around
{{cite web
|author=Staff writer(s)
|date=2015
|title=what
|publisher=National Science Foundation and UCSB School-University partnership
|url=http://scienceline.ucsb.edu/getkey.php?key=4306
Line 45 ⟶ 99:
|isbn=978-0534408336
|pages=781–782
|publisher=Thomson Brooks/Cole
}}</ref> to make the solid form of naphthalene evaporate into gas. On cool surfaces, the naphthalene vapours will solidify to form needle-like crystals.
===Iodine===
▲[[File:Sublimation reaction of naphthalene.jpg|thumb|Experimental set up for the sublimation reaction of [[naphthalene]] Solid naphthalene sublimes and form the crystal-like structure at the bottom of the [[watch glass]]]]
[[Iodine]] sublimes gradually and produces visible fumes on gentle heating
▲[[File:Crystal-like sublimated naphthalene.jpg|thumb|Solid compound of [[naphthalene]] sublimed to form a crystal-like structure on the cool surface.]]
===Other substances===▼
[[File:Camphor sublimation 1.jpg|thumb|upright|[[Camphor]] subliming in a [[cold finger]]. The crude product in the bottom is dark brown; the white purified product on the bottom of the cold finger above is hard to see against the light background.]]▼
▲[[Iodine]] produces fumes on gentle heating, although this is above the triple point and therefore not true sublimation. It is possible to obtain liquid iodine at atmospheric pressure by controlling the temperature at just above the melting point of iodine. In [[forensic science]], iodine vapor can reveal latent [[fingerprint]]s on paper.<ref>{{cite book
|last=Girard |first=James
|year= 2011
Line 61 ⟶ 111:
|pages= 143–144
}}</ref>
▲=== Other substances ===
[[Cadmium]] and [[zinc]] are not suitable [[materials for use in vacuum]] because they sublime much more than other common materials.{{citation needed|date=May 2019}}▼
▲[[File:Camphor sublimation 1.jpg|thumb|upright|[[Camphor]] subliming in a [[cold finger]]. The crude product in the bottom is dark brown; the white purified product on the bottom of the cold finger above is hard to see against the light background.]]
At [[atmospheric pressure]], [[arsenic]] sublimes gradually upon heating, and sublimes rapidly at {{convert|887|K|C}}.<ref name="Holl3">{{cite book |last=Holleman |first=Arnold F. |title=Lehrbuch der Anorganischen Chemie |author2=Wiberg, Egon |author3=Wiberg, Nils |date=1985 |publisher=Walter de Gruyter |isbn=978-3-11-007511-3 |edition=91–100 |pages=675–681 |language=de |chapter=Arsen}}</ref>
▲[[Cadmium]] and [[zinc]] sublime much more than other common materials, so they are not suitable [[materials for use in vacuum]]
==Purification by sublimation==
Line 82 ⟶ 136:
}}</ref>
For even higher purification efficiencies, a [[temperature gradient]] is applied, which also allows for the separation of different fractions. Typical setups use an evacuated glass tube that is heated gradually in a controlled manner. The material flow is from the hot end, where the initial material is placed, to the cold end that is connected to a pump stand. By controlling temperatures along the length of the tube, the operator can control the zones of re-condensation, with very volatile compounds being pumped out of the system completely (or caught by a separate [[cold trap]]), moderately volatile compounds re-condensing along the tube according to their different volatilities, and non-volatile compounds remaining in the hot end.
Vacuum sublimation of this type is also the method of choice for purification of organic compounds for use in the [[organic electronics|organic electronics industry]], where very high purities (often > 99.99%) are needed to satisfy the standards for consumer electronics and other applications.{{citation needed|date=October 2021}}
==Historical usage==
Line 105 ⟶ 159:
{{Main|Dye-sublimation printer}}
Dye-sub printing is a digital printing technology using full color artwork that works with polyester and polymer-coated substrates. Also referred to as digital sublimation, the process is commonly used for decorating apparel, signs and banners, as well as novelty items such as cell phone covers, plaques, coffee mugs, and other items with sublimation-friendly surfaces. The process uses the science of sublimation, in which heat and pressure are applied to a solid, turning it into a gas through an endothermic reaction without passing through the liquid phase.{{citation needed|date=October 2021}}
In sublimation printing, unique sublimation dyes are transferred to sheets of “transfer” paper via liquid gel ink through a piezoelectric print head. The ink is deposited on these high-release inkjet papers, which are used for the next step of the sublimation printing process. After the digital design is printed onto sublimation transfer sheets, it is placed on a heat press along with the substrate to be sublimated.{{citation needed|date=October 2021}}
In order to transfer the image from the paper to the substrate, it requires a heat press process that is a combination of time, temperature and pressure. The heat press applies this special combination, which can change depending on the substrate, to “transfer” the sublimation dyes at the molecular level into the substrate. The most common dyes used for sublimation activate at 350 degrees Fahrenheit. However, a range of 380 to 420 degrees Fahrenheit is normally recommended for optimal color.{{citation needed|date=October 2021}}
The
{{Table of phase transitions}}
==See also==
Line 119 ⟶ 176:
*[[Freezer burn]] – common process involving sublimation
*[[Phase diagram]]
*[[Phase transition|Phase transitions]]
▲{{Table of phase transitions}}
==References==
| |||