Question

Viscosity of a liquid arises due to strong intermolecular forces existing between the molecules. Stronger the intermolecular forces, greater is the viscosity. Name the intermolecular forces existing in the following liquids and arrange them in the increasing order of their viscosities. Also give reason for the assigned order in one line.
water, hexane `(CH_(3)CH_(2)CH_(2)CH_(2)CH_(2)CH_(3))`, glycernine `(CH_(2)OHCH(OH)CH_(2)OH)`

Answer 1

Water `(H_(2)O)` : Dipole-dipole interactions and hydrogen bonding.
Hexane `(C_(6)H_(14))` : London forces.
Glycerol `(C_(3)H_(8)O_(3))` : Dipole-dipole interactions and hydrogen bonding.
Viscosity of hexane is th minimum because the only attractive forces in the molecules of the hydrocarbon are weak London forces.
The viscosity of glycerol is more than that of water, because the extant of hydrogen bonding in glycerol is more.
The increasing order of viscosity of different liquids is
`"Hexane": lt "Water" lt "Glycerol"`