Find molar mass of nonvolatile solute when 20 g of it dissolved in 200 g water at 300 K . [Relative lowering of vapour pressure =0.02 ]

Step-by-step solution

The molar mass of a nonvolatile solute dissolved in a solvent can be determined from the relative lowering of vapor pressure using Raoult's law. For a dilute solution, the relative lowering of vapor pressure is approximately equal to the mole fraction of the solute: P^0 - P_s P^0 n₂ n₁ , where n₁ and n₂ represent the number of moles of solvent and solute, respectively. Given P^0 - P_s P^0 = 0.02 with 20 g of solute in 200 g of water (molar mass 18 g/mol), the moles of solvent are n₁ = 200 18 = 100 9 . Substituting