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| [image] | |
| General | |
|---|---|
| Molecular formula | C7H16 |
| CAS number | 142-82-5 |
| EC number | 205-563-8 |
| Physical characteristics | |
| Appearance | Colourless liquid |
| Melting point | 182 K (-91 °C) |
| Boiling point | 371 K (98 °C) |
| Vapour density | 3.5 |
| Vapour pressure | 40 mmHg (5.3 kPa) at 20 °C |
| Density | 0.684 g/cm³ |
| Flash point | −1 °C |
| Explosion limits | 1.1 to 7% |
| Autoignition temperature | 222 °C |
| Spectral data | |
| NMR spectra (n-heptane) | [ 1H NMR spectrum] [ 13C NMR spectrum] |
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.
| Alkanes | |||||||||||||||||||||||||||||||
| Methane CH4 | | | Ethane C2H6 | | | Propane C3H8 | | | Butane C4H10 | | | Pentane C5H12 | | | Hexane C6H14 | |||||||||||||||||||||
| heptane C7H16 | | | Octane C8H18 | | | Nonane C9H20 | | | Decane C10H22 | | | Undecane C11H24 | | | Dodecane C12H26 | |||||||||||||||||||||