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In thermodynamics, a critical point (or critical state) is the end point of a phase equilibrium curve. One example is the liquid–vapor critical point, the end point of the pressure–temperature curve that designates conditions under which a liquid and its vapor can coexist. At higher temperatures, the gas comes into a supercritical phase ...
The critical point remains a point on the surface even on a 3D phase diagram. An orthographic projection of the 3D p–v–T graph showing pressure and temperature as the vertical and horizontal axes collapses the 3D plot into the standard 2D pressure–temperature diagram. When this is done, the solid–vapor, solid–liquid, and liquid ...
The van der Waals equation, named for its originator, the Dutch physicist Johannes Diderik van der Waals, is an equation of state that extends the ideal gas law to include the non-zero size of gas molecules and the interactions between them (both of which depend on the specific substance). As a result the equation is able to model the liquid ...
Supercritical carbon dioxide (sCO2) is a fluid state of carbon dioxide where it is held at or above its critical temperature and critical pressure. Carbon dioxide usually behaves as a gas in air at standard temperature and pressure (STP), or as a solid called dry ice when cooled and/or pressurised sufficiently.
The reduced temperature of a fluid is its actual temperature, divided by its critical temperature: [1] = where the actual temperature and critical temperature are expressed in absolute temperature scales (either Kelvin or Rankine). Both the reduced temperature and the reduced pressure are often used in thermodynamical formulas like the Peng ...
Thermodynamics. According to van der Waals, the theorem of corresponding states (or principle/law of corresponding states) indicates that all fluids, when compared at the same reduced temperature and reduced pressure, have approximately the same compressibility factor and all deviate from ideal gas behavior to about the same degree. [1][2 ...
The (s) notation indicates equilibrium temperature of vapor over solid. Otherwise temperature is equilibrium of vapor over liquid. log10 of anydrous ammonia vapor pressure. Uses formula shown below. Vapor-pressure formula for ammonia: [4] log 10P = A – B / (T − C), where P is pressure in k Pa, and T is temperature in kelvins;
For an ideal gas, fugacity and pressure are equal, and so φ = 1. Taken at the same temperature and pressure, the difference between the molar Gibbs free energies of a real gas and the corresponding ideal gas is equal to RT ln φ. The fugacity is closely related to the thermodynamic activity. For a gas, the activity is simply the fugacity ...