Retrograde condensation occurs when

gas Gas is a state of matter that has neither a fixed volume nor a fixed shape and is a compressible fluid. A ''pure gas'' is made up of individual atoms (e.g. a noble gas like neon) or molecules of either a single type of atom ( elements such as ...

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 ...

: the so-called retrograde condensation.

Description

If the volume of two gases that are kept at constant

temperature Temperature is a physical quantity that quantitatively expresses the attribute of hotness or coldness. Temperature is measurement, measured with a thermometer. It reflects the average kinetic energy of the vibrating and colliding atoms making ...

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 eve ...

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 fossil gas, methane gas, and gas) is a naturally occurring compound of gaseous hydrocarbons, primarily methane (95%), small amounts of higher alkanes, and traces of carbon dioxide and nitrogen, hydrogen sulfide and helium ...

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 prese ...

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 the air needs to be cooled to (at constant pressure) in order to produce a relative humidity of 100%. This temperature depends on the pressure and water content of the air. When the air at a temperature above the ...

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

Discovery

Dutch physicist

Johannes Kuenen Johannes Petrus Kuenen (11 October 1866 in Leiden – 25 September 1922 in Leiden) 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 ...

discovered retrograde condensation and published his findings in April 1892 in his Ph.D. thesis with the title "Metingen betreffende het oppervlak van Van der Waals voor mengsels van koolzuur en chloormethyl" (Measurements on the Van der Waals surface for mixtures of

carbonic acid Carbonic acid is a chemical compound with the chemical formula . The molecule rapidly converts to water and carbon dioxide in the presence of water. However, in the absence of water, it is quite stable at room temperature. The interconversion ...

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 (whereas normal methane has the formula ). In formulas, the group is often abbreviated as ...

chloride The term chloride refers to a compound or molecule that contains either a chlorine anion (), which is a negatively charged chlorine atom, or a non-charged chlorine atom covalently bonded to the rest of the molecule by a single bond (). The pr ...

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

References

{{reflist Phase transitions Natural gas