Final answer:
Alcohols are soluble in water when they have short carbon chains because they can form hydrogen bonds with water molecules. With longer carbon chains, the nonpolar alkyl portion dominates, making the alcohol molecule more hydrophobic and thus less soluble in water.
Step-by-step explanation:
The property of alcohols that impacts their solubility in water involves the balance between the hydrophilic (water-attracting) and hydrophobic (water-repelling) parts of the molecule. Alcohols with a short carbon chain length, typically with one to three carbon atoms, exhibit complete solubility in water due to their ability to engage in hydrogen bonding with water molecules. The hydroxyl (-OH) groups in these short-chain alcohols form hydrogen bonds with the water, aiding in their dissolution.
However, as the carbon chain length increases, the hydrophobic character starts to dominate because the molecules resemble hydrocarbons, which are nonpolar and insoluble in water. This is why larger alcohols, such as 1-decanol, show diminished solubility in water. The polar -OH group is overwhelmed by the nonpolar alkyl part of the molecule, leading to decreased solubility.
To summarize, short-chain alcohols are soluble in water because of their ability to hydrogen bond with water, while long-chain alcohols are essentially insoluble due to the increased influence of their nonpolar alkyl chains.