|Jmol-3D images||Image 1|
|Molar mass||72.15 g mol−1|
|Density||0.626 g mL−1|
|Melting point||−130.5 to −129.1 °C; −202.8 to −200.3 °F; 142.7 to 144.1 K|
|Boiling point||35.9 to 36.3 °C; 96.5 to 97.3 °F; 309.0 to 309.4 K|
|Solubility in water||40 mg L−1 (at 20 °C)|
|Vapor pressure||57.90 kPa (at 20.0 °C)|
|kH||7.8 nmol Pa−1 kg−1|
|Refractive index (nD)||1.358|
|Viscosity||240 μPa s (at 20 °C)|
heat capacity C
|167.19 J K−1 mol−1|
|263.47 J K−1 mol−1|
|Std enthalpy of
|−174.1–−172.9 kJ mol−1|
|Std enthalpy of
|−3.5095–−3.5085 MJ mol−1|
|GHS signal word||DANGER|
|GHS hazard statements||H225, H304, H336, H411|
|GHS precautionary statements||P210, P261, P273, P301+310, P331|
|EU classification||F+ Xn N|
|R-phrases||R12, R51/53, R65, R66, R67|
|S-phrases||(S2), S16, S29, S33|
|Flash point||−49.0 °C (−56.2 °F; 224.2 K)|
|Supplementary data page|
|n, εr, etc.|
Solid, liquid, gas
|Spectral data||UV, IR, NMR, MS|
|Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)|
|(what is: / ?)|
Pentane is an organic compound with the formula C5H12 — that is, an alkane with five carbon atoms. The term may refer to any of three structural isomers, or to a mixture of them: in the IUPAC nomenclature, however, pentane means exclusively the n-pentane isomer; the other two being called "methylbutane" and "dimethylpropane". Cyclopentane is not an isomer of pentane.
|Common name||normal pentane
Pentanes are some of the primary blowing agents used in the production of polystyrene foam and other foams. Usually, a mixture of n-, i-, and increasingly cyclopentane is used for this purpose.
Pentanes are relatively inexpensive and are the most volatile alkanes that are liquid at room temperature, so they are often used in the laboratory as solvents that can be conveniently evaporated. However, because of their nonpolarity and lack of functionality, they can only dissolve non-polar and alkyl-rich compounds. Pentanes are miscible with most common nonpolar solvents such as chlorocarbons, aromatics, and ethers. They are also often used in liquid chromatography.
The boiling points of the pentane isomers range from about 9 to 36 °C. As is the case for other alkanes, the more branched isomers tend to have lower boiling points.
The same trend normally holds for the melting points of alkane isomers, and indeed that of isopentane is 30 °C lower than that of n-pentane. However, the melting point of neopentane, the most heavily branched of the three, is 100 °C higher that of isopentane. The anomalously high melting point of neopentane has been attributed to the better solid-state packing assumed to be possible with its tetrahedral molecule; but this explanation has been challenged on account of it having a lower density than the other two isomers.2
Like other alkanes, pentanes are under standard room temperature and conditions largely unreactive - however, with sufficient activation energy (i.e. an open flame), they get readily oxidized to form carbon dioxide and water:
- C5H12 + 8 O2 → 5 CO2 + 6 H2O
- C5H12 + Cl2 → C5H11Cl + HCl
Such reactions are unselective; with n-pentane, the result is a mixture of the 1-, 2-, and 3-chloropentanes, as well as more highly chlorinated derivatives. Other radical halogenations can also occur.
- Record of n-Pentane in the GESTIS Substance Database from the IFA, accessed on 19 April 2011
- James Wei (1999), Molecular Symmetry, Rotational Entropy, and Elevated Melting Points. Ind. Eng. Chem. Res., volume 38 issue 12, pp. 5019–5027 doi:10.1021/ie990588m
- From the values listed at Standard enthalpy change of formation (data table).
- Roman M. Balabin (2009). "Enthalpy Difference between Conformations of Normal Alkanes: Raman Spectroscopy Study of n-Pentane and n-Butane". J. Phys. Chem. A 113 (6): 1012. doi:10.1021/jp809639s. PMID 19152252.
- International Chemical Safety Card 0534 at ILO.org
- NIOSH Pocket Guide to Chemical Hazards at CDC.gov
- Phytochemical data for pentane at Ars-grin.gov