\(\mathrm{C}_{2} \mathrm{H}_{6}\) and \(\mathrm{C}_{6} \mathrm{H}_{6}\) are both hydrocarbons. What is the difference between them?

In hydrocarbons, there are mostly carbon (C) and hydrogen (H) atoms. To classify these hydrocarbons, we can look at how these atoms are bonded or arranged. There are two main types: aliphatic hydrocarbons, which consist of alkanes, alkenes, and alkynes, and aromatic hydrocarbons. The hydrocarbon with the formula \(\mathrm{C}_{2} \mathrm{H}_{6}\) has 2 carbon atoms and 6 hydrogen atoms. This is an example of an alkane, which follows the general formula \(\mathrm{C}_{n} \mathrm{H}_{2n+2}\). Alkanes are characterized by single covalent bonds between carbon atoms. In this case, there is only one bond between the two carbon atoms. The hydrocarbon with the formula \(\mathrm{C}_{6} \mathrm{H}_{6}\) has 6 carbon atoms and 6 hydrogen atoms. This is an example of an aromatic hydrocarbon, specifically benzene. Aromatic hydrocarbons have a cyclic structure and alternating single and double bonds between the carbon atoms.

For the alkane \(\mathrm{C}_{2} \mathrm{H}_{6}\), we have a linear structure with the two carbon atoms bonded by a single bond, and the hydrogen atoms surrounding the carbon atoms: H H | | C-C | | H H For the aromatic hydrocarbon \(\mathrm{C}_{6} \mathrm{H}_{6}\) (benzene), we have a cyclic structure consisting of 6 carbon atoms in a ring, with a hydrogen atom bonded to each carbon atom: H H \ / C=C--C=C / \ H H \ / C=C--C=C / \ H H

Alkanes like \(\mathrm{C}_{2} \mathrm{H}_{6}\) are generally non-reactive and have lower boiling and melting points compared to aromatic hydrocarbons. Since they have only single bonds, they undergo substitution reactions, in which a hydrogen atom is replaced by another atom or group of atoms. Aromatic hydrocarbons like \(\mathrm{C}_{6} \mathrm{H}_{6}\) are highly stable due to their cyclic structure and alternating single and double bonds, which create a delocalized electron cloud. This gives them unique properties, such as a distinct smell, and makes them generally more reactive than alkanes. They undergo electrophilic aromatic substitution reactions, in which a hydrogen atom is replaced by an electrophile (electron-seeking species). In conclusion, the main difference between the hydrocarbons \(\mathrm{C}_{2} \mathrm{H}_{6}\) and \(\mathrm{C}_{6} \mathrm{H}_{6}\) lies in their structures, classifications (alkane vs. aromatic hydrocarbon), and chemical properties.