Why is water bipolar?

Answer 1

The molecule of water is made of two atoms of hydrogen bonded to one atom of oxygen. Now the oxygen atom being electronegative pulls the bonded pair of electrons and hydrogen being electropositive let the electrons to be pulled towards the oxygen atom. So, there is a slight -ive charge on O-atom and slight +ive charge on H-atoms. Now the H-O-H molecule i.e. the water molecule is not linear but at an angle of 109.47 degrees, so according to the law of vector addition there is a net -ive charge on the O-atom and net +ive charge on H-atoms, thus making it a bipolar molecule. It is important because of this bipolar nature only water becomes a universal solvent. Any solute dissolves in a solvent only if its molecules are able to make a bonds with the solvent molecules with bond energy more than its lattice energy (the energy by which the molecules of solute are bonded with each other). When a solute is added to water, its +ive part makes bond with O-atom and the -ive part makes bond with the H-atom (of course these bonds are not permanent but are weak intermolecular H-bonding). Also the highly electronegative O-atom provides high ionising power to water. This property of universal solubility and high ionising power is very important for many of the life's reactions to support life and the living world.