When ethanol is added to water, what do its molecules do?

When ethanol is added to water, its molecules primarily form hydrogen bonds with water. Ethanol contains hydroxyl groups (-OH) that can engage in hydrogen bonding, which is a key type of intermolecular attraction. The -OH group in ethanol is polar, allowing it to interact favorably with the polar water molecules. This interaction helps to stabilize the mixture, leading to the solubility of ethanol in water.

The formation of hydrogen bonds between ethanol and water molecules is significant because it facilitates the mixing of the two substances, enabling them to combine into a homogeneous solution rather than remaining as separate layers. This ability to form hydrogen bonds explains the behavior of ethanol in an aqueous environment and is critical for understanding concepts related to solubility and molecular interactions in chemistry.