Solutions are
classified as solid, liquid and gaseous solutions The concentration of a solution is
expressed in terms of mole fraction, molarity, molality and in percentages The
dissolution of a gas in a liquid is governed by Henry’s law, according to which, at a
given temperature, the solubility of a gas in a liquid is directly proportional to
the partial pressure of the gas The vapour pressure of the solvent is lowered by
the presence of a non-volatile solute in the solution and this lowering of vapour
pressure of the solvent is governed by Raoult’s law, according to which the relative
lowering of vapour pressure of the solvent over a solution is equal to the mole
fraction of a non-volatile solute present in the solution