Retrograde condensation occurs when

gas Gas is one of the four fundamental states of matter (the others being solid, liquid, and plasma). A pure gas may be made up of individual atoms (e.g. a noble gas like neon), elemental molecules made from one type of atom (e.g. oxygen), or ...

in a tube is compressed beyond the point of condensation with the effect that the liquid evaporates again. This is the opposite of

condensation Condensation is the change of the state of matter from the gas phase into the liquid phase, and is the reverse of vaporization. The word most often refers to the water cycle. It can also be defined as the change in the state of water vapor to ...

: the so-called retrograde condensation.

Description

If the volume of two gases that are kept at constant

temperature Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer. Thermometers are calibrated in various temperature scales that historically have relied o ...

and

pressure Pressure (symbol: ''p'' or ''P'') is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled ''gage'' pressure)The preferred spelling varies by country and e ...

below critical conditions is gradually reduced, condensation will start. When a certain volume is reached, the amount of condensation will gradually increase upon further reduction in volume until the gases are liquefied. If the composition of the gases lies between their true and pseudo critical points the condensate formed will disappear on continued reduction of volume. This disappearance of condensation is called retrograde condensation. Because most

natural gas Natural gas (also called fossil gas or simply gas) is a naturally occurring mixture of gaseous hydrocarbons consisting primarily of methane in addition to various smaller amounts of other higher alkanes. Low levels of trace gases like carbo ...

found in

petroleum reservoir A petroleum reservoir or oil and gas reservoir is a subsurface accumulation of hydrocarbons contained in porous or fractured rock formations. Such reservoirs form when kerogen (ancient plant matter) is created in surrounding rock by the presence ...

s is not a pure product, when non-associated gas is extracted from a field under supercritical pressure/temperature conditions (i.e., the pressure in the reservoir decreases below

dewpoint The dew point is the temperature to which air must be cooled to become saturated with water vapor, assuming constant air pressure and water content. When cooled below the dew point, moisture capacity is reduced and airborne water vapor will co ...

condensate Condensate may refer to: * The liquid phase produced by the condensation of steam or any other gas * The product of a chemical condensation reaction, other than water * Natural-gas condensate, in the natural gas industry * ''Condensate'' (album) ...

liquids may form during the isothermic depressurizing, an effect called retrograde condensation.

Discovery

Johannes Petrus Kuenen Johannes Petrus Kuenen (Leiden, 11 October 1866 – Leiden, 25 September 1922) was a Dutch physicist. Biography Kuenen was the son of the professor of theology Abraham Kuenen and his wife Wiepkje Muurling. His son Philip Henry Kuenen was pro ...

discovered retrograde condensation and published his findings in April 1892 with the title "Metingen betreffende het oppervlak van Van der Waals voor mengsels van koolzuur en chloormethyl" (Measurements on the

Van der Waals surface The Van der Waals surface of a molecule is an abstract representation or model of that molecule, illustrating where, in very rough terms, a surface might reside for the molecule based on the hard cutoffs of Van der Waals radii for individual at ...

for mixtures of carbonic acid and

methyl In organic chemistry, a methyl group is an alkyl derived from methane, containing one carbon atom bonded to three hydrogen atoms, having chemical formula . In formulas, the group is often abbreviated as Me. This hydrocarbon group occurs in many ...

chloride The chloride ion is the anion (negatively charged ion) Cl−. It is formed when the element chlorine (a halogen) gains an electron or when a compound such as hydrogen chloride is dissolved in water or other polar solvents. Chloride salts ...

).Measurements on the surface of Van der Waals for mixtures of carbonic acid and methyl chloride

References

{{reflist Phase transitions Natural gas