1. The problem asks: What causes the solubility of alkanols in water? 2. Alkanols (alcohols) have a general formula $C_nH_{2n+1}OH$ and contain a hydroxyl group ($-OH$). 3. The solubility of alkanols in water is primarily due to the ability of the hydroxyl group to form hydrogen bonds with water molecules. 4. Hydrogen bonding occurs when the hydrogen atom of the hydroxyl group, which is slightly positive, interacts with the lone pairs of electrons on the oxygen atom of water molecules. 5. This interaction allows alkanols to dissolve in water, especially those with shorter carbon chains where the hydrophobic effect is less dominant. 6. As the carbon chain length increases, the hydrophobic (water-repelling) alkyl part becomes larger, reducing solubility. 7. Therefore, the key factor for solubility is the hydrogen bonding capability of the $-OH$ group with water. Final answer: The solubility of alkanols in water is due to hydrogen bonding between the hydroxyl group of alkanols and water molecules.