Colligative Property 1
The colligative properties are also called the democrative properties. These are discussed as follows:-
- Relative lowering of vapor pressure:-
According to Raoult’s Law the vapour pressure of a solution containing non-volatile solute is given by the formula
p_{S} = x_{B} X P^{0}_{B} ---------------(1)
where x_{B} = mole fraction of solvent and p^{0}_{B} = vapour pressure of solvent in pure state. If x_{A} is the mole fraction of solute.
x_{A} + x_{B} = 1 or x_{B} = 1 – x_{A}
Substituting in equation (1)
p_{S} = P^{0}_{B} (1 – x_{A})
Where W_{A} and M_{A} are the weight and molar mass of solute and W_{B} and M_{B} are the weight and molar mass of solvent.
Since the law is applicable to dilute solutions for which W_{A} << W_{B}, hence W_{A} can be
Or