ABSTRACT
Water, alcohols, and glycols deviate from hydrocarbons by having more polar forces acting between the molecules. Water has a molecular weight of 18.0, which is similar to that of methane (M
=
16.0), but the absolute critical temperature of water is more than three times higher than that of methane, and the critical pressure is almost five times higher. This is because of attractive (association) forces acting between the water molecules, which make water behave as a substance of a somewhat higher molecular weight.
