What happens to the solubility of alcohols in water as the number of carbon atoms increases?

As the number of carbon atoms in alcohols increases, their solubility in water typically decreases. This trend is due to the structure of alcohol molecules, which consist of a hydrophobic hydrocarbon chain and a hydrophilic hydroxyl (-OH) group.

In smaller alcohols, such as methanol or ethanol, the hydroxyl group is relatively large compared to the carbon chain, and these molecules can form strong hydrogen bonds with water, enhancing their solubility. However, as the carbon chain lengthens, the hydrophobic nature of the hydrocarbon part becomes more dominant. The longer carbon chains do not interact favorably with water, leading to a situation where the molecule's ability to dissolve in water diminishes as the chain becomes longer.

Consequently, while the hydroxyl group still provides some degree of solubility, the increasing hydrophobic character of the larger carbon chains outweighs this, resulting in reduced solubility in water. Therefore, the solubility of alcohols in water decreases as the number of carbon atoms increases.