Question

How is the lowering in vapour pressure related to elevation in boiling point?

Answer 1

Answer:

boiling point elevation. a solvent pressure will lower when a solute is added .this happen because of displacement of solvent molecule by solute..... the the lower number of solvent molecule at the surface means that fewer will evaporate and Thus the pressure is lowered.

Answer 2

Answer:

(1) The boiling point of a liquid is the temperature at which the vapour pressure of the liquid bccomes equal to the external pressure, generally 1 atm $\sf{(101.3 x 10^3 Nm^{-2} )}$.

(2) When a iquid is heated, its vapour pressure ises till it becomes equal to the external presSure.lf the liquid has a low vapour pressure, it has a higher boiling point.

(3) When a nonvolatile solute is added to a solvent, its vapour pressure decreases, hence the boiling point increases. This is explained by graphical representation of the vapour pressure and the boiling point of the pure solvent and the solution.

If $\sf{T_0}$, and Tare the boiling points of a pure solvent and a solution, then the elevation in the boiling point is given by, ΔT = $\sf{T - T_0}$

The curve AB, represents the variation in the vapour pressure of a pure solvent with temperature while curve CD represents the variation in the vapour pressure of the solution.

(4) This elevation in the boiling point is proportional to the lowering of the vapour pressure, i.e., $\sf{P_0 - P}$, where $\sf{P_0}$ and P are the vapour pressures of the pure solvent and the solution.