Pentane (\(C_5H_{12}\)) is an organic compound that belongs to the alkane family, meaning it is a saturated hydrocarbon consisting only of single bonds between carbon atoms. It is a colorless, volatile, and highly flammable liquid with a characteristic gasoline-like odor. Pentane exists in three structural isomers: n-pentane (a straight chain), isopentane (2-methylbutane), and neopentane (2,2-dimethylpropane), although "pentane" in IUPAC nomenclature typically refers specifically to n-pentane.
| Pentane |
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Physical Properties
Color - Colorless
Odor - Gasoline-like Odor
Density - \(0.02262 \; lbm/in^3 \;\)@\(\; 68 \; F^\circ \; (0.6262 \; g/cc \;\)@\(\; 20 \; C^\circ)\)
Viscosity - \(0.224 \; cP \;\)@\(\; 77 \; F^\circ \; (0.224 \; cP \;\)@\(\; 25 \; C^\circ)\)
Molar Mass - \(72.15 \; g/mol \;(72.15 \; g/mol)\)
Vapor Pressure - \(0.75 \; torr \;\)@\(\; -0.580 \; F^\circ \; (0.1000 \;bar \;\)@\(\; -18.1 \; C^\circ)\)
Surface Tension - \(15.49 \; dynes/cm \;(15.49 \; dynes/cm ) \)
Chemical Properties
Chemical Formula - \(C_5H_{12}\)
Condensed Structural Formula - \(CH_3(CH_2)_3CH_3\)
State of Matter - Liquid
Flammability - Highly Flammable
Electrical Properties
Dielectric Constant - \(1.844 \;(1.844)\)
Thermal Properties
Melting Point - \(-201.6 \; F^\circ \; (-129.8 \; C^\circ)\)
Boiling Point - \(96.98 \; F^\circ \; (36.1 \; C^\circ)\)
Flash Point - \(-56 \; F^\circ \; (-49 \; C^\circ)\)
Autoignition Temp. - \(500 \; F^\circ \; (260 \; C^\circ)\)
Heat of Fusion - \(50.08 \; BTU/lb \; (116.4 \; J/g)\)
Heat of Vaporization - \(153.8 \; BTU/lb \; (357.4 \; J/g)\)
Specific Heat Capacity - \(0.5538 \; BTU/lbF^\circ \;\)@\(\; 77 \; F^\circ \; (2.317 \; J/gC^\circ \;\)@\(\; 25 \; C^\circ )\)
Thermal Conductivity - \(0.0999 \;\)@\(\; 77 \; F^\circ \; (0.0114 \;\)@\(\; 25 \; C^\circ )\)
Optical Properties
Refractive Index - \(1.3575 \;\)@\(\; 68 \; F^\circ \; \lambda \; 589.3 \; mm \; (1.3575 \;\)@\(\; 20 \; C^\circ \; \lambda \; 589.3 \; mm)\)
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Pentane is naturally found in crude oil and as a byproduct of natural gas production. Pentane with the molecular formula \(C_5H_{12}\) and the condensed structural formula \(CH_3(CH_2)_3CH_3\) refer to the same chemical compound. \(C_5H_{12}\) is the molecular formula, indicating that the molecule contains five carbon atoms and twelve hydrogen atoms. \(CH_3(CH_2)_3CH_3\;\)is a condensed structural formula that shows the arrangement of these atoms in a straight chain, explicitly detailing the methyl \((CH_3)\) groups at the ends and the three methylene \((CH_2)\) groups in the middle. Both formulas represent n-pentane, which is the straight-chain isomer of pentane.
