Resublimate
Various processes are referred to as resublimation :
- in the thermodynamics immediate transitioning of a substance from the gaseous to the solid aggregate state ( phase transition ),
- a method of fabric cleaning and separation, in which a sublimation process is carried out several times in a row.
This article describes the phase transition, which is also known as resublimation , desublimation , solidification or deposition .
Under the pressure and temperature conditions under which resublimation occurs, there is no liquid aggregate state, as can be seen in the phase diagram on the right. These conditions are also referred to as sublimation pressure and sublimation temperature , or as sublimation point , regardless of the direction of the phase transition . This in turn is part of the sublimation pressure curve of the phase diagram, which in the adjacent example shows the phase boundary line between solid and liquid below the triple point .
During its resublimation, every substance releases what is known as the heat of sublimation , which is equal to the sum of the heat of fusion and evaporation .
This process can be observed in the freezer compartment of a refrigerator , for example . The as water vapor contained in the air water is immediately fixed in contact with the cold walls without previously trained liquid water. The result is an icy refrigerator compartment that has to be defrosted from time to time.
Further examples are the formation of ice flowers and the formation of hoar frost and polar snow .
The phase change in the opposite direction is called sublimation .
literature
- Tönjes de Vries, Antje Paschmann: Resublimation - the fascinating formation of hoarfrost . In: CHEMKON . tape 11 , no. 4 , 2004, ISSN 0944-5846 , p. 185–190 , doi : 10.1002 / ckon.200410016 .