Calculate the relative lowering of vapour pressure of solution containing 0.56 g nonvolatile solute in 100 g water [ molar mass of solute =60 ~g ~mol ⁻¹ ]

Step-by-step solution

The relative lowering of vapour pressure is given by Raoult's law, P^0 - P_s P^0 = X_ solute = n_ solute n_ solute + n_ solvent . For a solute mass of 0.56 ~ g with molar mass 60 ~ g mol ⁻¹ , n_ solute = 0.56 60 = 0.009333 ~ mol . For water as solvent with mass 100 ~ g and molar mass 18 ~ g mol ⁻¹ , n_ solvent = 100 18 = 5.5556 ~ mol . The mole fraction is then X_ solute = 0.009333 0.009333 + 5.5556 = 0.009333 5.564933 0.0017 . The relative lowering of vapour pressure is 0.0017 , confirming option B.