15.2 Water as Solvent

Water is the universal solvent because it can dissolve almost all the minerals. Its ability to dissolve substances is because of two unique properties of water:

(i) Polarity of water molecule; (ii) Exceptional hydrogen bonding ability.

Polar nature of water

Water molecule has polar structure, i.e. one end of the molecule is partially positive while the other end is partially negative because of electronegativity difference between oxygen and hydrogen atoms.

All other polar substances are soluble in water, because the positive end of the substance is attracted by the negative end $({\mathrm{O}}^{\mathrm{d}})$$(\mathrm{O^{d}})$ of the water and negative end of the substance is attracted by the positive end $({\mathrm{H}}^{\mathrm{d}+})$$(\mathrm{H^{d + }})$ of the water. The electrostatic attractions among the ions are overcome by the ion- dipole forces of attraction between ion and water molecules.