Difference Between Octane and Cetane l Octane vs Cetane

The key difference between Octane and Cetane is that Octane has 8 carbon atoms whereas Cetane has sixteen carbon atoms per molecule. Furthermore, Octane is highly volatile while Cetane is not volatile.

Both these are hydrocarbon compounds that are used as references for the ranking of different engine fuels according to their performance (octane rating and cetane rating). Furthermore, both these are colorless liquids at room temperature that readily undergo ignition.


1. Overview and Key Difference
2. What is Octane
3. What is Cetane
4. Side by Side Comparison – Octane vs Cetane in Tabular Form
5. Summary

What is Octane?

Octane is a flammable hydrocarbon having the chemical formula C8H18. It is also an alkane (no double bonds or triple bonds present between two atoms). Since this compound is a low molecular weight hydrocarbon, it is highly volatile (the liquid phase easily converts into the vapor phase). This liquid is less dense than water; hence, it floats on water. That is because it is insoluble in water since it is a nonpolar liquid (water is a polar solvent). In addition, it can form an irritating odor via volatilization.

Chemical Properties Octane

Some chemical facts about this compound are as follows:

  • Chemical formula = C8H18
  • Molar mass = 114.23 g/mol
  • Melting point =-56.8 °C
  • Boiling point = 126°C
  • Appearance = colorless liquid
  • Odor = gasoline-like odor