Deposition (phase transition)

This diagram shows the nomenclature for the different phase transitions.

Deposition is a process in which gas transforms into solid (also known as desublimation). The reverse of deposition is sublimation.

One example of deposition is the process by which, in sub-freezing air, water vapor changes directly to ice without first becoming a liquid. This is how snow forms in clouds, as well as frost and hoar frost on the ground. Another example is when frost forms on a leaf which is also caused by deposition. For deposition to occur thermal energy must be removed from a gas. When the leaf becomes cold enough, water vapor in the air surrounding the leaf loses enough thermal energy to change into a solid.

Another example of physical deposition is the artificial process of lamaw physical vapor deposition, used to deposit thin films of various materials onto various surfaces.

Deposition releases energy and is an exothermic phase change.

References

• Jacobson, Mark Z., Fundamentals of Atmospheric Modeling, Cambridge University Press, 2nd ed., 2005, p. 525 ISBN 978-0521839709
• Moore, John W., et. al., Principles of Chemistry: The Molecular Science, Brooks Cole, 2009, p. 387 ISBN 978-0495390794
• Whitten, Kenneth W., et. al., Chemistry, Brooks-Cole, 9th ed., 2009, p. 7 ISBN 978-0495391630
• Glencoe Science "Focus on Physical Science"