Alkanes

Have you heard that bio gas produced using the waste disposed from poultry farms is used as a fuel? The main component of it which is important as a fuel is methane gas. This gas is also present in the marsh gas produced when organic matter decays in marshes.

This is the simplest hydrocarbon and has the formula CH4 . Its structure is shown in the figure. During the mining of mineral oils, the gas ethane comes out from oil wells. Ethane is also a hydrocarbon. Its formula is C2 H6 . The structure corresponding to this formula is as follows.

Consider the methane and ethane molecules described above. Bonds between carbon atoms and hydrogen atoms (only) are present in the methane molecule. But in the ethane molecule there are bonds between carbon and carbon atoms. The hydrocarbons which have only single bonds between carbon atoms are referred to as alkanes.

Alkanes are a series of compounds. This series has several common characteristics. One of those is that all the compounds in that series can be represented by a common formula.

The common formula of the alkane set is Cn H2n+2. In this, 'n' is the number of carbon atoms in a molecule of the compound. According to the above formula, the formula of the simplest alkane methane can be obtained as follows.

Listed in below Table are the formula and names of the alkanes of which the number of carbon atoms varies from 1 to 5.
The fuel petrol (gasoline) is a mixture of alkanes. The most abundant alkane in it is octane represented by the formula C8 H18. L.P. gas, another mixture of alkanes/ mainly contain alkanes propane (C3 H8 ) and butane (C4 H10).

Table  presents the molecular formulae and structural formulae of the alkanes with carbon atoms 1 - 5.