Alkane · C₇H₁₆
The zero point of the octane scale — a reference fuel hydrocarbon. Octane-rating reference fuel, a nonpolar solvent, and a naphtha component.
| Formula | C₇H₁₆ |
| CAS number | 142-82-5 |
| Synonyms | heptane |
| Molar mass | 100.2 g/mol (Computed from the molecular formula and CODATA atomic weights) |
| Normal boiling point | 98.38 °C (NIST Chemistry WebBook (webbook.nist.gov)) |
| Liquid density | 684 kg/m³ (Reference liquid density near 20–25 °C (NIST WebBook)) |
Antoine equation (mmHg/°C): log₁₀(P) = 6.90253 − 1267.828 / (216.823 + T), valid -2–124 °C. Source: NIST Chemistry WebBook (webbook.nist.gov).
| °C | kPa | bar | mmHg | psia |
|---|---|---|---|---|
| -2.0 | 1.34 | 0.0134 | 10.0 | 0.194 |
| 23.2 | 5.56 | 0.0556 | 41.7 | 0.807 |
| 48.4 | 17.67 | 0.1767 | 132.5 | 2.563 |
| 73.6 | 45.92 | 0.4592 | 344.4 | 6.660 |
| 98.8 | 102.45 | 1.0245 | 768.5 | 14.860 |
| 124.0 | 203.02 | 2.0302 | 1522.7 | 29.445 |
Using its Antoine constants (NIST Chemistry WebBook (webbook.nist.gov)), the saturation pressure of n-heptane at 25 °C is about 6.09 kPa. Use the calculator above for any temperature within -2–124 °C.
n-Heptane boils at 98.38 °C at atmospheric pressure (NIST Chemistry WebBook (webbook.nist.gov)). At that temperature its vapor pressure equals one atmosphere (760 mmHg).
n-Heptane (C₇H₁₆, CAS 142-82-5) has a molar mass of 100.2 g/mol.