Octane Number of Gasoline

Definition:
The octane number of gasoline is a measure of its resistance to knock, which is the spontaneous combustion of fuel-air mixture in the engine's combustion chamber.

Explanation:
The octane number is the percentage of iso-octane (C8H18) in a mixture of iso-octane and n-heptane (C7H16) that exhibits the same knocking characteristics as the gasoline being tested. Gasoline with a higher octane number has a greater resistance to knock and is, therefore, more suitable for high-performance engines.

Factors affecting octane rating:
Several factors affect the octane rating of gasoline, including the chemical composition, the degree of saturation, and the size of the hydrocarbon molecules. The presence of additives like tetraethyl lead and ethanol can also increase the octane rating.

Importance:
The octane number is a critical parameter in the selection of gasoline for different types of engines. Engines with high compression ratios and high operating temperatures require gasoline with a higher octane rating to prevent knocking and engine damage.

Conclusion:
In summary, the octane number of gasoline is a measure of its knocking tendency or resistance to spontaneous combustion in the engine's combustion chamber. Gasoline with a higher octane rating is better suited for high-performance engines with high compression ratios and operating temperatures.