One example of deposition is the process by which, in sub-freezingair, water vapour changes directly to ice without first becoming a liquid. This is how frost and hoar frost form on the ground or other surfaces. Another example is when frost forms on a leaf. For deposition to occur, thermal energy must be removed from a gas. When the air becomes cold enough, water vapour in the air surrounding the leaf loses enough thermal energy to change into a solid. Even though the air temperature may be below the dew point, the water vapour may not be able to condense spontaneously if there is no way to remove the latent heat. When the leaf is introduced, the supercooled water vapour immediately begins to condense, but by this point is already past the freezing point. This causes the water vapour to change directly into a solid.
Another example is the soot that is deposited on the walls of chimneys. Soot molecules rise from the fire in a hot and gaseous state. When they come into contact with the walls they cool, and change to the solid state, without formation of the liquid state. The process is made use of industrially in combustion chemical vapour deposition.
Industrial applicationsedit
There is an industrial coatings process, known as evaporative deposition, whereby a solid material is heated to the gaseous state in a low-pressure chamber, the gas molecules travel across the chamber space and then deposit to the solid state on a target surface, forming a smooth and thin layer on the target surface. Again, the molecules do not go through an intermediate liquid state when going from the gas to the solid. See also physical vapor deposition, which is a class of processes used to deposit thin films of various materials onto various surfaces.
Deposition releases energy and is an exothermic phase change.
deposition, phase, transition, this, article, includes, list, references, related, reading, external, links, sources, remain, unclear, because, lacks, inline, citations, please, help, improve, this, article, introducing, more, precise, citations, january, 2020. This article includes a list of references related reading or external links but its sources remain unclear because it lacks inline citations Please help improve this article by introducing more precise citations January 2020 Learn how and when to remove this template message Deposition is the phase transition in which gas transforms into solid without passing through the liquid phase Deposition is a thermodynamic process The reverse of deposition is sublimation and hence sometimes deposition is called desublimation Water vapour from humid winter air deposits directly into a solid crystalline frost pattern on a window without ever being liquid in the process Contents 1 Applications 1 1 Examples 1 2 Industrial applications 2 See also 3 ReferencesApplications editExamples edit One example of deposition is the process by which in sub freezing air water vapour changes directly to ice without first becoming a liquid This is how frost and hoar frost form on the ground or other surfaces Another example is when frost forms on a leaf For deposition to occur thermal energy must be removed from a gas When the air becomes cold enough water vapour in the air surrounding the leaf loses enough thermal energy to change into a solid Even though the air temperature may be below the dew point the water vapour may not be able to condense spontaneously if there is no way to remove the latent heat When the leaf is introduced the supercooled water vapour immediately begins to condense but by this point is already past the freezing point This causes the water vapour to change directly into a solid Another example is the soot that is deposited on the walls of chimneys Soot molecules rise from the fire in a hot and gaseous state When they come into contact with the walls they cool and change to the solid state without formation of the liquid state The process is made use of industrially in combustion chemical vapour deposition Industrial applications edit There is an industrial coatings process known as evaporative deposition whereby a solid material is heated to the gaseous state in a low pressure chamber the gas molecules travel across the chamber space and then deposit to the solid state on a target surface forming a smooth and thin layer on the target surface Again the molecules do not go through an intermediate liquid state when going from the gas to the solid See also physical vapor deposition which is a class of processes used to deposit thin films of various materials onto various surfaces Deposition releases energy and is an exothermic phase change See also editPhase transitions of matter vte ToFrom Solid Liquid Gas Plasma Solid Melting Sublimation Liquid Freezing Vaporization Gas Deposition Condensation Ionization Plasma RecombinationReferences editGaja Shiv P Fundamentals of Atmospheric Modeling Cambridge University Press 2nd ed 2005 p 525 ISBN 978 0 521 83970 9 Moore John W et al Principles of Chemistry The Molecular Science Brooks Cole 2009 p 387 ISBN 978 0 495 39079 4 Whitten Kenneth W et al Chemistry Brooks Cole 9th ed 2009 p 7 ISBN 978 0 495 39163 0 Focus on Physical Science Glencoe Science nbsp This article about statistical mechanics is a stub You can help Wikipedia by expanding it vte Retrieved from https en wikipedia org w index php title Deposition phase transition amp oldid 1219552443, wikipedia, wiki, book, books, library,
