Other Definitions
heptane (dict)
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Heptane | big>Heptane | | gcolor="#a0ffa0" colspan="2"| General | | lign="left"| Molecular formula | C7H16 | | lign="left"| CAS number | 142-82-5 | | lign="left"| EC number | 205-563-8 | | gcolor="#a0ffa0" colspan="2"| Physical characteristics | | lign="left"| Appearance | Colourless liquid | | lign="left"| Melting point | 182 K (-91 Celsius) | | lign="left"| Boiling point | 371 K (98 Celsius) | | lign="left"| Vapour density | 3.5 | | lign="left"| Vapour pressure | 40 mm Hg at 20 Celsius | | lign="left"| Specific gravity | 0.684 | | lign="left"| Flash point | -1 Celsius | | lign="left"| Explosion limits | 1.1 - 7% | | lign="left"| Autoignition temperature | 222 Celsius | | gcolor="#a0ffa0" colspan="2"| Spectral data | | lign="left"| NMR spectra | 1H NMR spectrum of n-heptane 13C NMR spectrum of n-heptane | Heptane (also known as dipropyl methane, gettysolve-C or heptyl hydride) is an alkane hydrocarbon with the chemical formula CH3(CH2)5CH3. Heptane has nine isomers. The isomer n-heptane (straight-chain heptane) has been selected as the zero point of the octane rating scale. It is undesirable in petrol, as it burns explosively, causing engine knocking, as opposed to branched-chain octane isomers, which burn more slowly and give better performance. Its choice for the zero point of the scale was due to the availability of very high purity n-heptane, unmixed with other isomers of heptane or other alkanes, distilled from the resin of Jeffrey Pine. Other sources of heptane and octane, produced from crude oil, contain a mixture of different isomers with greatly differing ratings, so do not give a precise zero point. External links
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