Difference Between Benzene and Gasoline

Benzene vs Gasoline
 

Benzene

Benzene only has carbon and hydrogen atoms arranged to give a planar structure. It has the molecular formula of C₆H₆.  Its structure and some of the properties are as follows.

Molecular weight: 78 g mole^-1

Boiling point:  80.1 ^oC

Melting point:  5.5 ^oC

Density:  0.8765 g cm^-3

Benzene is a colorless liquid with a sweet odor.  It is flammable and evaporates quickly when exposed. Benzene is used as a solvent, because it can dissolve a lot of non polar compounds. However, benzene is slightly soluble in water.  The structure of benzene is unique compared to other aliphatic hydrocarbons; therefore, benzene has unique properties. All the carbons in benzene have three sp² hybridized orbitals. Two sp² hybridized orbitals of a carbon overlap with sp² hybridized orbitals of adjacent carbons in either side. Other sp² hybridized orbital overlaps with the s orbital of hydrogen to form a σ bond. The electrons in p orbitals of a carbon overlap with the p electrons of carbon atoms in both sides forming pi bonds. This overlap of electrons happens in all the six carbon atoms and, therefore, produces a system of pi bonds, which are spread over the whole carbon ring. Thus, these electrons are said to be delocalized. The delocalization of the electrons means that there aren’t alternating double and single bonds. So all the C-C bond lengths are the same, and the length is between single and double bond lengths.  Because of the delocalization, the benzene ring is stable; it is reluctant to undergo addition reactions, unlike other alkenes.

Gasoline

Gasoline is a mixture of a large number of hydrocarbons, which have 5-12 carbons. There are aliphatic alkanes like heptane, branched alkanes like isooctane, aliphatic cyclic compounds and small aromatic compounds. However, there are no alkenes or alkynes other than these hydrocarbons. Gasoline is a natural by- product of petroleum industry, and it is a non renewable source.  Gasoline is produced in the fractional distillation of crude oil. When they are separated based on their boiling points, the low molecular weighted compounds in the gasoline are collected in the same range. Gasoline, sometimes, in some countries, also known as petrol, which is a fuel used in internal-combustion  engines of vehicles. The combustion of gasoline produces a high amount of heat energy and carbon dioxide and water. Additional compounds have mixed with gasoline in order to enhance its usage in engines. Hydrocarbons like isooctane or benzene and toluene are added to gasoline, to increase its octane rating. This octane number measures the ability of an engine to cause self ignition in the engine cylinders (which causes knocking). When gasoline and air mixture are caught in premature ignition, before the spark is passed from the spark plug, it pushes against the crankshaft producing a knocking sound. Due to knocking the engine tends to overheat and loose power. Therefore, it damages the engine in the long run. So to reduce this octane number of the fuel has to be increased. Other than adding hydrocarbons stated above, the octane number can also be increased by adding certain lead compounds. This will increase the octane number; thus, gasoline will be more resistant to self ignition, which causes knocking. Gasoline prices are largely varying over time with the price of crude oil. Since gasoline has become a primary need in most of the countries, the variation in oil prices affects the country’s economy too.