Question

The magnitude of surface tension of liquid depends on the attractive forces between the molecules. Arrange the following in increasing order of surface tension:

water, alcohol \[\ce{(C2H5OH)}\] and hexane \[\ce{[CH3(CH2)4CH3)]}\].

Answer 1

Water and alcohol are polar molecules which have high electronegative O atm so they have hydrogen bonding along with dipole-dipole interaction. Hexane is a nonpolar molecule that has London dispersion force which is a weak force between the molecules. Water has stronger H-bonding than alcohol. So, the order of attractive force will be:

Hexane < Alcohol < Water

More attractive forces between the molecules, the greater the magnitude of surface tension of the liquid.