Real gas
In its thermal equation of state, the real gas deviates from the linear dependence of pressure on density and temperature , which makes up the ideal gas . The deviations are based on the fact that the particles have a finite extent (not point masses ) and attract each other at greater distances, e.g. B. by Van der Waals forces .
The interactions can be compared with the Lennard-Jones potential , the compressibility factor and u. a. can also be described in approximate approximation with the Joule-Thomson coefficient . Thus the attractive forces predominate at a great distance, but when two particles fall below a certain distance from each other, the repulsive (repulsive) force component begins to predominate, which increases extremely quickly (with r 12 or exponentially ).
If a very high level of accuracy is not required, one is usually content with the Van der Waals equation for describing the state of a real gas. However, there are a number of other equations of state :
- Virial equations
- Clausius equation
- Dieterici's equation of state
- Redlich-Kwong equation of state
- Redlich-Kwong-Soave equation of state
- Peng-Robinson equation of state
- Benedict-Webb-Rubin equation of state
- Berthelot's equation of state
- Equation of state of Wohl
literature
- B. Weigand, J. Köhler, J. von Wolfersdorf: Thermodynamics compact . 3rd edition, Springer 2013, ISBN 978-3-642-37232-2
- Jan Peter Gehrke, Patrick Köberle: Physics during studies: a bridging course . De Gruyter Studium 2014, ISBN 978-3-11-035931-2 (Chapter "Real Gases" pp. 142–150)