Hydrogen bonding and solubility


When an substance dissolves in water the particles of that substance are separated from each other by the molecules of water. Electrostatic attraction between the particles of the substance and the strong dipoles of the water molecules are responsible for separating the solute particles.

A substance(solute) will dissolve if the attraction between the particles of the substance and the water(solvent) molecules is strong enough to overcome the solute-solute and solvent-solvent forces of attraction.

The water molecule is polar and hydrogen bonding exists between the molecules of water. As far as intermolecular bonding forces are concerned hydrogen bonding is relatively strong.
Methanol is soluble in water. Like water, methanol has relatively strong hydrogen bonding acting between its molecules. The attraction between methanol and water is strong enough to overcome the methanol-methanol and water-water intermolecular forces of attraction.
Some ionic substances, such as sodium chloride, are soluble in water. The forces of attraction between the ions and water molecules are strong enough to overcome the ion-ion and water-water force of attraction. The force of attraction between the ion and the water molecule is known as ion-dipole attraction.
Notice how the polar water molecule binds to the different ions.