Octane

From Free net encyclopedia

For other uses, see Octane (disambiguation).

Octane
Image:Octane.png Image:Octane molecule 3D model.png
General
Molecular formula	C₈H₁₈
SMILES	CCCCCCCC
Molar mass	114.22 g/mol
Appearance	colorless liquid
CAS number	[111-65-9]
Properties
Density and phase	0.703 g/ml, liquid
Solubility in water	Immiscible
Melting point	−57 °C (216 K)
Boiling point	125.5 °C (398.7 K)
Viscosity	0.542 cP at 20 °C
Thermodynamic data
Std enthalpy change of formation, Δ_fH^o_liquid	−250 kJ/mol
Std enthalpy change of combustion, Δ_cH^o_liquid	−5430 kJ/mol
Standard molar entropy, S^o_liquid	360 J·K⁻¹·mol⁻¹
Hazards
MSDS	External MSDS
EU classification	Flammable (F) Harmful (Xn) Dangerous for the environment (N)
NFPA 704	Template:Nfpa
R-phrases	Template:R11, Template:R38, Template:R50/53, Template:R65, Template:R67
S-phrases	Template:S2, Template:S9, Template:S16, Template:S29, Template:S33, Template:S60, Template:S61, Template:S62
Flash point	13 °C
Autoignition temperature	220 °C
Explosive limits	1.0–6.5%
RTECS number	RG8400000
Supplementary data page
Structure and properties	n, ε_r, etc.
Thermodynamic data	Phase behaviour Solid, liquid, gas
Spectral data	UV, IR, NMR, MS
Related compounds
Related alkanes	Heptane 2,2,4-Trimethylpentane
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references

Octane is an alkane with the chemical formula C₈H₁₈. It has many isomers.

One of the isomers, 2,2,4-trimethylpentane or isooctane, is of major importance, as it has been selected as the 100 point on the octane rating scale, with n-heptane as the zero point. Octane ratings are ratings used to represent the anti-knock performance of petroleum-based fuels (octane is less likely to prematurely combust under pressure than heptane), given as the percentage of 2,2,4-trimethylpentane in an 2,2,4-trimethylpentane / n-heptane mixture that would have the same performance. It is an important constituent of gasoline.

Octane has 18 isomers :