A solution of a non-volatile solute in water has a boiling point of 375.3K. Calculate the vapour pressure of water above this solution at 338K. Given, p_(0) (water) = 0.2467 atm at 338K and K_(b) for water = 0.52.

A solution of a non-volatile solute in water has a boiling point of 37

1.	A solution of a non-volatile solute in water has a boiling point of 375.3K. Calculate the vapour pressure of water above this solution at 338K. Given, p_(0) (water) = 0.2467 atm at 338K and K_(b) for water = 0.52.
Answer» Solution :`DeltaT_(b)=(375.3-373.16)=2.15K` We know that, `DeltaT_(b)`= Molality `XX K_(b)` 2.15 = Molality `xx 0.52` Molality `= (2.15)/(0.52) = 4.135` i.e., 4.135 moles of the SOLUTE present in 1000g of water (55.5 moles) Mole fraction of water `= (55.5)/(4.135+55.5)=(55.5)/(59.635)` VAPOUR pressure of water above solution = Mole fraction `xx p_(0)` `=(55.5)/(59.635)xx0.2467=0.23`atm.