Question

The vapour pressure of water is 12.3 kPa at 300 K. Calculate vapour pressure of 1 molal solution of a non-volatile solute in it. 

Answer 1

1 molal solution means 1 mol of the solute is present in 100 g of the solvent (water). Molar mass of water = 18 g mol−¹

                                                             ^=1000/18

 Number of moles present in 1000 g of water

 = 55.56 mol 

Therefore, mole fraction of the solute in the solution is