Alkane · C₈H₁₈
A gasoline-range alkane used in fuel and solvent blends. Gasoline-range component and a reference hydrocarbon in fuel and solvent work.
| Formula | C₈H₁₈ |
| CAS number | 111-65-9 |
| Synonyms | octane |
| Molar mass | 114.23 g/mol (Computed from the molecular formula and CODATA atomic weights) |
| Normal boiling point | 125.6 °C (NIST Chemistry WebBook (webbook.nist.gov)) |
| Liquid density | 703 kg/m³ (Reference liquid density near 20–25 °C (NIST WebBook)) |
Antoine equation (mmHg/°C): log₁₀(P) = 6.92374 − 1355.126 / (209.517 + T), valid 19–152 °C. Source: NIST Chemistry WebBook (webbook.nist.gov).
| °C | kPa | bar | mmHg | psia |
|---|---|---|---|---|
| 19.0 | 1.31 | 0.0131 | 9.9 | 0.191 |
| 45.6 | 5.46 | 0.0546 | 40.9 | 0.791 |
| 72.2 | 17.31 | 0.1731 | 129.9 | 2.511 |
| 98.8 | 45.02 | 0.4502 | 337.7 | 6.530 |
| 125.4 | 100.57 | 1.0057 | 754.4 | 14.587 |
| 152.0 | 199.62 | 1.9962 | 1497.3 | 28.952 |
Using its Antoine constants (NIST Chemistry WebBook (webbook.nist.gov)), the saturation pressure of n-octane at 25 °C is about 1.86 kPa. Use the calculator above for any temperature within 19–152 °C.
n-Octane boils at 125.6 °C at atmospheric pressure (NIST Chemistry WebBook (webbook.nist.gov)). At that temperature its vapor pressure equals one atmosphere (760 mmHg).
n-Octane (C₈H₁₈, CAS 111-65-9) has a molar mass of 114.23 g/mol.