meaning of octan number?

Answer 1

Octane number

A standard laboratory measure of a fuel's ability to resist knock during combustion in a spark-ignition engine, A single-cylinder four-stroke engine of standardized design is used to determine the knock resistance of a given fuel by comparing it with that of primary reference fuels composed of varying proportions of two pure hydrocarbons, one very high in knock resistance and the other very low. A highly knock-resistant isooctane (2,2,4-trimethylpentane, C8H18) is assigned a rating of 100 on the octane scale, and normal heptane (C7H16), with very poor knock resistance, represents zero on the scale. Octane number is defined as the percentage of isooctane required in a blend with normal heptane to match the knocking behavior of the gasoline being tested. See also Spark knock.

For fuels with a rating higher than 100 octane, the rating is usually obtained by determining the amount of tetraethyllead compound that needs to be added to pure isooctane to match the knock resistance of the test fuel.

Answer 2

Strictly speaking, an octan(e) number of 100 means a fuel burns as well as pure isooctane (aka 2,2,4-trimethylpentane). An octane number of 0 means a fuel burns as well as n-heptane, and that wouldn't be very well at all!

These are the two arbitrary fixed points on the octane number scale, kind of like freezing and boiling points of water are the arbitrary fixed points on the celsius temperature scale.

Answer 3

8

Answer 4

octane is the measure of resistance to burning.... the higher the number the harder to ignite therefore If a car is Pinging (Preignition) making the fuel harder to ignite (higher octane ratiing) will cause the fuel to ignite later and therefore quieter.

Answer 5

octane is the measure of resistance to burning

Answer 6

If you mean "octet", that is the outermost level of electrons on an atom, which needs 8 electrons to become stable.