Question

At 298k the vapoir pressure of water is 23.75 mmhg calculate the vapour pressure at thr same temperature over 5% aqeuos soln of urea

Answer 1

The vapour pressure of pure liquid
p∘A=150torr  

V.P of liquid B in solution ps=105torr

Let mole fraction of solute B=xm

B=xm
Using Raoult's law
 x0=(p0−vs)/p0=(150−105)/150