Properties of Octane (C8H18)
Octane is a hydrocarbon compound found in gasoline that is used as a measure of its performance in internal combustion engines. The octane rating of gasoline indicates its resistance to knocking or pinging, which are undesirable forms of combustion that can lead to engine damage. The higher the octane rating, the more resistant the fuel is to knocking.
The following table provides a comprehensive list of octane properties in both SI and US customary/Imperial units at normal temperature and pressure (NTP).
Click on the icon to switch between Metric and Imperial units.
| Physical Properties | Metric |
|---|---|
| Molar Mass | 114.23 g/mol |
| Density | 703 kg/m3 |
| Dynamic Viscosity | 0.542 mPa·s |
| Surface Tension | 21.62 mN/m |
| Thermal Properties | Metric |
| Melting Point | -56.7 °C |
| Boiling Point | 125.6 °C |
| Thermal Conductivity | 0.1281 W/m·K |
| Coefficient of Thermal Expansion (αV) (25°C) | 1.16×10-3 1/°C |
| Vapor Pressure | 1.4 kPa |
| Critical Constants | Metric |
| Critical Temperature (Tc) | 296 °C |
| Critical Pressure (Pc) | 2.48 MPa |
| Critical Molar Volume (Vc) | 492 cm3/mol |
| Electrical Properties | Metric |
| Relative Permittivity (εr) | 1.948 |
| Optical Properties | Metric |
| Refractive Index (589 nm) | 1.397 |
| Hazardous Data | Metric |
| Flash Point | 13 °C |
| Autoignition Temperature | 206 °C |
| Lower Flammability Limit | 1% |
| Upper Flammability Limit | 6.5% |
| NFPA Rating (Health) | 1 |
| NFPA Rating (Fire) | 3 |
| NFPA Rating (Reactivity) | 0 |
Unless stated otherwise, all values are taken at room temperature (approximately 20°C or 68°F) and 1 atm pressure. (1 atm = 101,325 Pa)
Related Pages
References: 1) Cardarelli, François. Materials Handbook: A Concise Desktop Reference. Switzerland: Springer International Publishing, 2018. 2) CRC Handbook of Chemistry and Physics, 97th Edition. United Kingdom: CRC Press, 2016-2017. 3) Yaws, Carl L. The Yaws Handbook of Physical Properties for Hydrocarbons and Chemicals. Netherlands: Elsevier Science, 2015. 4) Fire Protection Guide to Hazardous Materials, 14th Edition. United States: National Fire Protection Association, 2010.