Question

What are hydrocarbons? Give one example.

Answer 1

A hydrocarbon is an organic chemical compound which is composed exclusively of only hydrogen and carbon atoms. Hydrocarbons are the compounds that occur in nature and form the basis of crude oil, natural gas, coal, and other important energy sources which are extracted from their ores.

Complete step by step answer:
According to the rules of IUPAC, the hydrocarbons are classified as:
(i) Saturated hydrocarbons are the simplest of the hydrocarbon species. They are composed entirely of single bonds and are saturated with hydrogen. The formula for acyclic saturated hydrocarbons (i.e., alkanes) is ${C_n}{H_{2n + 2}}$ . The most general form of saturated hydrocarbons is ${C_n}{H_{2n + 2(1 - r)}}$ , where ‘r’ is the number of rings. Those with exactly one ring are known to be cycloalkanes. Saturated hydrocarbons are the basis of petroleum fuels and are found as either linear or branched species. The characteristic property of such compounds is substitution reaction (like chlorination reaction to form chloroform).
(ii) Unsaturated hydrocarbons have one or more double or triple bonds, or simply multiple bonds, between carbon atoms. Those with double bonds are called alkenes. Those with one double bond have the formula ${C_n}{H_{2n}}$ (assuming non-cyclic structures). Those which contain triple bonds are known as an alkyne. Those which have one triple bond have the formula ${C_n}{H_{2n - 2}}$ .
(iii) Aromatic hydrocarbons, also known as arenes, are hydrocarbons that have at least one aromatic ring.
One example of a hydrocarbon is benzene. It is an aromatic hydrocarbon consisting of six carbon atoms and twelve hydrogen atoms. It consists of $6\pi -$ electrons in the ring or three double bonds which regularly get delocalized and are stabilized by resonance.

Note: Hydrocarbons from which one hydrogen atom has been removed are functional groups called hydrocarbons. Such compounds which have a free valence site can be substituted with any group to give a diverse number of compounds. Hydrocarbons are generally colorless and hydrophobic with only weak odors.