Question
Thu April 12, 2012 By: Anshul
 

What is meant by octane number and cetane number? Which compounds have octane number zero and hundred? Which compounds have cetane number zero and hunderd?

Expert Reply
Mon April 16, 2012

The cetane number of a diesel oil is the percentage of cetane (hexadecane) by volume in a mixture of cetane and ? -methyl naphthalene which has the same ignition property as the fuel oil under consideration. The cetane number of 1-methylnaphthalene is zero and of hexadecane is 100.

Octane number is used for measuring the knocking character of fuel used in petrol engine. The octane number of a given sample may be defined as the percentage by volume of iso-octane present in a mixture of iso-octane and n-heptane which has the same knocking performance as the fuel itself.

Isooctane (upper) has an octane rating of 100 whereas n-heptane has an octane rating of 0.

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