Question
State Raoult’s law. If AT is the elevation of boiling point of a solvent and m is the number of moles of solute per kg of solvent, what is the realationship between T and m?
Solution
Raoult’s law: It states that whenever a non-volatile solute is added to a volatile solvent the vapour pressure of the solvent is lowered and the lowering of vapour pressure s directly proportional to the mole-fraction of the solute added.
pA ∝ xA
or
where P0A is the vapour pressure of the pure solvent.
PA is the vapour pressure of the solution.
XB is the mole fraction of non-volatile solute.
Thus, according to Raoult’s law, the relative lowering of vapour pressure is equal to the mole-fraction of the solute in solution.
pA ∝ xA
or
where P0A is the vapour pressure of the pure solvent.
PA is the vapour pressure of the solution.
XB is the mole fraction of non-volatile solute.
Thus, according to Raoult’s law, the relative lowering of vapour pressure is equal to the mole-fraction of the solute in solution.
