Fractional destillation

Fractional distillation is a process by which petroleum is destillated into fractions, and hydrocarbons in this case, according to each boiling point. In this process, the crude oil is heated so that it vaporizes, separates, and then condenses.

The fractions obtained from crude oil are the following:

Fraction	Composition of carbon chain
Natural gas	Methane, ethane, propane and butane.
Petroleum ether (solvent)	Pentane and hexane.
Naphtha (solvent)	Heptane and octane.
Gasoline	Pentane, hexane, heptane , octane, nonane, decane, undecane and dodecane.
Kerosene	Dodecane, tridecane, tetradecane and pentadecane.
Fuel oils, mineral oils	Pentadecane, hexadecane, heptadecane and octadecane.
Lubricating oil, petroleum jelly greases, paraffin wax, asphalt	Hexadecane, heptadecane, octadecane, nonadecane, heneicosane, dodosane, traicosane and tetracosane.

Engine knock is a sound an engine makes when gasoline ignites too soon because of poor engine timing or the case of law octane fuel. It may cause overheating, loss of power, and engine damage. It occurs in the engine cylinder and often, prior to spark ignition. The sound cames form the vibration of the piston, connecting rod, and leanings.