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Structural formula
Structural formula of propane

Structural formula of propane
Structural formula with all drawn atoms (above) - simplified skeletal formula (below)
Surname propane
other names
Molecular formula C 3 H 8
Brief description

colorless and odorless gas

External identifiers / databases
CAS number 74-98-6
EC number 200-827-9
ECHA InfoCard 100,000,753
PubChem 6334
ChemSpider 6094
Wikidata Q131189
Molar mass 44.10 g mol −1
Physical state


  • 2.01 g l −1 (gaseous, 0 ° C, 1013 hPa)
  • 0.5812 g cm −3 (liquid, at boiling point)
Melting point

−187.7 ° C

boiling point

−42.1 ° C

Vapor pressure

0.836 M Pa (20 ° C)


practically insoluble in water (75 mg l −1 at 20 ° C)

Dipole moment

0.084 D (2.8 x 10 -31  C  ·  m )

safety instructions
GHS hazard labeling from  Regulation (EC) No. 1272/2008 (CLP) , expanded if necessary
02 - Highly / extremely flammable 04 - gas bottle


H and P phrases H: 220-280
P: 210-377-381-403

DFG / Switzerland: 1000 ml m −3 or 1800 mg m −3

Thermodynamic properties
ΔH f 0

−103.8 kJ / mol

As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Propane is a colorless flammable gas and belongs to the hydrocarbons . It is in third place in the homologous series of alkanes .


Propane is a colorless gas , has a melting point of −187.7 ° C and a boiling point of −42 ° C. The critical temperature is 96.8 ° C, the critical pressure is 4.2 M Pa and the critical density is 0.22 g · cm −3 .

Propane crystallizes in space group P 2 1 / n (space group no. 14, position 2) . The packing of the molecules is rather bad, the space filling at 90 K is only 58.55%. This is the reason why the melting point is lower than that of all other alkanes . Template: room group / 14.2

Propane can easily be liquefied by compression. It does not dissolve very much in water : at 20 ° C to 75 mg · l −1 .

Propane is heavier than air and has a narcotic to asphyxiating effect in high concentrations .

Propane is extremely flammable and forms explosive mixtures in air between 2.12% and 9.35% by volume . Its ignition temperature is 470 ° C (according to DIN 51794). The calorific value is 93 M J · m −3 or 46.35 MJ / kg (12.88 kWh / kg).


Propane is a naturally occurring gas . It is created together with other hydrocarbons such as petroleum and butane through the decomposition and reaction of organic substances over long periods of time. Propane is released from oil fields by separating it from other hydrocarbons and refining it for commercial use.

Propane is produced by separating and collecting the gas from its petroleum sources. Propane is isolated from petroleum by separating it from the natural gas phase and by refining crude oil from petrochemical mixtures .

Both processes begin when underground oil fields are developed by drilling oil wells. The hydrocarbon mixture is directed from the well into a gas trap that separates the stream into crude oil and gas, which includes petroleum , liquefied petroleum gases, and natural gas . The mixture of liquefied gases can be used as a mixture or further separated into its three parts butane , isobutane and propane.

Industrial propane is in the promotion of natural gas as a by-product recovered and in a petroleum refinery in the cracking of petroleum produced.

In the laboratory , propane can be synthesized by adding hydrogen to propene :

Synthesis of propene

So that the addition reaction can take place, z. B. platinum or palladium catalysts are used.


Energy source

American design
propane cylinder
Truck with propane tanks

Consumption is increasing rapidly in non-industrialized areas of the world. Propane has replaced many older traditional energy sources .

Propane is used as a liquid gas for combustion and heating purposes, e.g. B. as autogas (LPG) to drive vehicles , in the firing of hot air balloons , in gas stoves and gas boilers, in gas grills , for soldering and welding equipment , gas rechauds or lighters . Usually it is mixed with butane , e.g. B. 40% propane and 60% butane.

Among the industries that use propane include glass manufacturer , brick factories , poultry farms and other industries, the portable heat need. In rural areas , it is used to heat livestock, in grain dryers and other heat generating devices. If it for heating or drying of grain is used, it is usually in a large, fixed gas tank kept, which is replenished from a propane-vans.


As a refrigerant , it has the designation R-290 and is used in cooling devices and heat pumps . In Australia, propane is already in more than one million car - air conditioners used. Propane has a low global warming potential (3.3 times the same amount of carbon dioxide ), no ozone depletion potential and can act as a substitute for R-12 , R-22 , R-134a and other chlorofluorocarbons . However, old systems must not simply be filled with propane, as it is flammable . Separate safety regulations must be met for propane systems.


Propane is a possible component of the propellant gas in spray cans ( food additive E 944) and airsofts . It is used on a large scale for the production of ethene and propene .


Gas container for storing propane

Propane is liquefied under pressure and stored in gas cylinders or tanks made of metal or composite materials. The internal cylinder pressure is determined exclusively by the vapor pressure of the connection and is only dependent on the ambient temperature. It is therefore not determined by the filling level of the pressurized gas cylinder and is, for example, 4.7 bar at 0 ° C, 8.4 bar at 20 ° C and 17.1 bar at 50 ° C. The internal pressure drops (as with all liquid gases stored under pressure) only when all liquid propane has evaporated.

It is also stored in underground caverns . Storage is preferably done in the low-consumption months in order to be able to cover consumption peaks in winter.


Propane burns with sufficient oxygen to form carbon dioxide and water :

If there is not enough oxygen for complete combustion , incomplete combustion will occur. The result, in turn, is carbon dioxide, water and heat . But carbon monoxide is also formed .

Individual evidence

  1. Entry on PROPANE in the CosIng database of the EU Commission, accessed on February 21, 2020.
  2. Entry on E 944: Propane in the European database for food additives, accessed on August 11, 2020.
  3. a b c d e f g h i j k l Entry on propane in the GESTIS substance database of the IFA , accessed on February 1, 2016(JavaScript required) .
  4. David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Permittivity (Dielectric Constant) of Gases, pp. 6-188.
  5. Entry on propane in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on February 1, 2016. Manufacturers or distributors can expand the harmonized classification and labeling .
  6. Swiss Accident Insurance Fund (Suva): Limit values ​​- current MAK and BAT values (search for 74-98-6 or propane ), accessed on November 2, 2015.
  7. David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Standard Thermodynamic Properties of Chemical Substances, pp. 5-24.
  8. a b c d e f g h i j Entry on propane. In: Römpp Online . Georg Thieme Verlag, accessed on May 30, 2014.
  9. ^ Roland Boese, Hans-Christoph Weiss, Dieter Bläser: The Melting Point Alternation in the Short-Chainn-Alkanes: Single-Crystal X-Ray Analyzes of Propane at 30 K and ofn-Butane ton-Nonane at 90 K. In: Angewandte Chemistry International Edition. 38, 1999, p. 988, doi : 10.1002 / (SICI) 1521-3773 (19990401) 38: 7 <988 :: AID-ANIE988> 3.0.CO; 2-0 .
  10. Visualization Spatial representation of molecules and crystal structures at , accessed on June 28, 2016.
  11. ^ Marcin Podsiadło, Anna Olejniczak, and Andrzej Katrusiak: Why Propane? The Journal of Physical Chemistry C, 2013, 117, 4759-4763 .
  12. Advameg, Inc .: Propane
  13. 2016 Propane Market Outlook . Propane Education and Research Council.
  14. Manfred Petz (Ed.): Hydrocarbons as refrigerants. Expert-Verlag, 1995, ISBN 3-8169-1186-2 , pp. 59-76.
  15. ^ Federal Environment Agency: Natural Refrigerants for Mobile Air-Conditioning in Passenger Cars.
  16. ZZulV : Text of the additive approval regulation
  17. DGUV publications: Handling of portable liquid gas cylinders in fire , accessed on June 6, 2020.
  18. Elgas Ltd .: LPG Gas Blog


  • Geert Oldenburg: Propane - Butane . Springer 1955, OCLC 17854737 .

Web links

Commons : Propane  - Collection of pictures, videos and audio files
Wiktionary: Propane  - explanations of meanings, word origins, synonyms, translations