How are alcohols classified in a homologous series?

Alcohols are classified in a homologous series based on the number of carbon atoms in their molecular structure.

In more detail, a homologous series is a group of organic compounds that have a similar structure and chemical properties, and they differ by a constant unit, which is -CH2- in the case of alcohols. The simplest alcohol is methanol (CH3OH), which has one carbon atom. The next one is ethanol (C2H5OH), which has two carbon atoms. This pattern continues with propanol (C3H7OH), butanol (C4H9OH), and so on.

The general formula for alcohols is CnH2n+1OH, where 'n' represents the number of carbon atoms. This formula helps to predict the molecular structure of any member of the alcohol homologous series. For example, if 'n' is 3, the formula becomes C3H7OH, which is propanol.

The physical and chemical properties of alcohols change gradually with increasing molecular size. For instance, as the number of carbon atoms increases, the boiling point of the alcohol also increases. This is due to the increase in the strength of the intermolecular forces, which require more energy to overcome.

In terms of chemical properties, all alcohols are able to form hydrogen bonds due to the presence of the -OH group. This makes them relatively polar and able to mix with water. However, as the size of the alcohol increases, the non-polar carbon chain becomes dominant, making the alcohol less soluble in water.

In summary, the classification of alcohols in a homologous series is based on the number of carbon atoms in their molecular structure, which affects their physical and chemical properties.