Question

Mole fraction to molality. Convert 0.1538 mole fraction of propanol (C3H8O) in water to molality. (Hint: begin by assuming 1 mole total and determine the contributing moles of propanol and contributing moles of water.) Answer to 4 significant figures with appropriate units.

Answer 1

Assume total one mole of solution

no of moles of propanol = 0.1538 mole

no of moles of water     = 1-0.1538 = 0.8462 moles of water

mass of propanol         = no of moles of propanol* molar mass of propanol

                                 = 0.1538*60

                                = 9.228 gm

mass of water            = no of moles of water* molar mass of water

                               = 0.8462*18

                              = = 15.23 gm

molality                   = weight of solute*1000/Gram molar mass of solute*weitht of solvent in gm

                              = 9.228*1000/60 * 15.23

                              = 9228/913.8

                             = 10.09 m >>>>answer