Does methanol from hydrogen bonds with itself or water?
Methanol (CH3OH) can form hydrogen bonds with both itself and with water.
Within a sample of pure methanol, the molecules can engage in intermolecular hydrogen bonding. This is possible because methanol has a hydroxyl group (–OH), which contains a highly electronegative oxygen atom bonded to a hydrogen atom. This creates a polar bond, with the hydrogen atom carrying a partial positive charge and the oxygen atom carrying a partial negative charge. As a result, hydrogen atoms from one methanol molecule can form a hydrogen bond with the oxygen atom of a neighboring methanol molecule.
When methanol is mixed with water, it can also form hydrogen bonds with water molecules. Water (H2O) is a highly polar molecule with an oxygen atom that can accept hydrogen bonds and hydrogen atoms that can donate hydrogen bonds. Methanol's oxygen can act as a hydrogen bond acceptor from water's hydrogen, and methanol's hydrogen attached to the oxygen can act as a hydrogen bond donor to water's oxygen atom.
These hydrogen bonding interactions are important as they determine many physical properties of the mixed liquid, such as boiling point, solubility, and viscosity. Methanol is completely miscible with water, partly due to its ability to form hydrogen bonds with water molecules.