How does the solubility of alcohols change with increasing molecular size?

The solubility of alcohols in water decreases with increasing molecular size due to the increasing presence of hydrocarbon chains. Alcohols consist of a hydroxyl group (-OH) that is polar and can interact favorably with water molecules, promoting solubility. However, as the size of the alcohol's hydrocarbon chain increases, the non-polar characteristics of the hydrocarbon portion dominate.

This non-polar region does not interact well with water, leading to a situation where the overall solubility in water decreases. For example, small alcohols like methanol and ethanol are highly soluble due to their relatively short hydrocarbon chains and strong hydrogen bonding with water. In contrast, larger alcohols such as octanol have much longer hydrocarbon chains that hinder their ability to interact with water, resulting in lower solubility.

Thus, the relationship between the size of the alcohol molecule and its solubility in water is inversely related, with larger alcohols becoming less soluble.