Which property of carboxylic acids allows them to dissolve in water?

Carboxylic acids are able to dissolve in water primarily due to their ability to form hydrogen bonds. This functional group contains a carbonyl (C=O) and a hydroxyl (-OH) group, which are polar and can interact favorably with water molecules. The oxygen atoms in both the carbonyl and the hydroxyl groups are highly electronegative, allowing them to attract the positively charged hydrogen atoms of water molecules.

When carboxylic acids are mixed with water, they can form hydrogen bonds with water, which helps to break the intermolecular forces holding the acid molecules together. This interaction increases the solubility of the carboxylic acids in water, as the water molecules effectively surround and solvate the acid molecules.

Other properties listed, such as the presence of aromatic rings, low molecular weight, and partial ionization in solution, do not provide a direct explanation for water solubility. For instance, while low molecular weight may contribute to increased solubility in some cases, it is the hydrogen bonding that plays the critical role in enabling carboxylic acids to dissolve in water effectively.