Pentane

Pentane
IUPAC name	Pentane
Identifiers
CAS number	109-66-0
PubChem	8003
EC number	203-692-4
DrugBank	DB03119
MeSH	pentane
ChEBI	CHEBI:37830
RTECS number	RZ9450000
SMILES	CCCCC
Beilstein Reference	969132
Gmelin Reference	1766
Properties
Molecular formula	C5H12
Molar mass	72.15 g mol-1
Appearance	Colourless, transparent liquid
Odor	Odourless
Density	626 mg mL−1
Melting point	-130--129 °C, 142.7-144.1 K, -203--200 °F
Boiling point	36-36 °C, 309.0-309.4 K, 97-97 °F
Solubility in water	40 mg L−1 (at 20 °C)
log P	3.255
Vapor pressure	57.90 kPa (at 20.0 °C)
kH	7.8 nmol Pa−1 kg−1
Acidity (pKa)	~45
Basicity (pKb)	~59
λmax	200 nm
Refractive index (nD)	1.358
Viscosity	0.240 cP (at 20 °C)
Thermochemistry
Std enthalpy of formation ΔfHo298	−174.1–−172.9 kJ mol−1
Std enthalpy of combustion ΔcHo298	−3.5095–−3.5085 MJ mol−1
Standard molar entropy So298	263.47 J K−1 mol−1
Specific heat capacity, C	167.19 J K−1 mol−1
Hazards
EU classification	F+ Template:Hazchem Xn N
EU Index	601-006-00-1
NFPA 704	4 1 0
R-phrases	Template:R12, R51/53, Template:R65, Template:R66, Template:R67
S-phrases	Template:S2, Template:S16, Template:S29, Template:S33
Flash point	−49.0 °C
Autoignition temperature	260.0 °C
Explosive limits	1.4–8.3%
Related compounds
Related alkanes	Butane Butyl iodide Hexane
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)

Pentane is an alkane. Its chemical formula is C₅H₁₂. Usually, pentane represents all three isomers (n-pentane, isopentane and neopentane). But in the IUPAC, pentane only represents n-pentane. In the IUPAC, the other two isomers is 2-methylbutane and 2,2-dimethylpropane. Cyclopentane's chemical formula is C₅H₁₀, so it is not an isomer of pentane.

Isomers

Common name	normal pentane unbranched pentane n-pentane	isopentane	neopentane
IUPAC name	pentane	2-methylbutane	2,2-dimethylpropane
Molecular diagram
Skeletal diagram

Reaction

All isomers of pentane burn with oxygen to make carbon dioxide and water:

C₅H₁₂+8O₂->5CO₂+6H₂O.