3.0 Physical properties of the alcohols

The alcohols are neutral substance, the lower members are liquids and have a distinctive smell and a burning test the higher members are solids and are almost odorless.

In a group of isomeric alcohols, the primary alcohols have the highest boiling points and the tertiary the lowest, with the secondary having an individuate value. The lower members are less volatile than it is to be expected from their molecular weights and this is due to the association through hydrogen bonding extending over a chain of molecules, thus giving rise to a large molecule the volatility of which would be expected to be low.

The lower alcohols are very soluble in water and the solubility diminishes as the molecular weight increases. Their solubility of water is to be expected. Since the oxygen atom of the hydroxyl group in alcohol can form a hydrogen bond with the water molecule. In the lower alcohols, the hydroxyl group constitutes a large part of the molecule. Whereas the molecular weight of the alcohol increases the hydrocarbon character of the molecule increases and hence the solubility is water decreases. This, however, is not a complete story, the structure of carbon chain plays also a part e.g. n-butanol is fairly soluble in water but t-butanol is miscible with water in all proportions.