posted by Sarah on .
An aqueous antifreeze solution is 40.0% ethylene glycol (C2H6O2) by mass. The density of the solution is 1.05 g/cm3. Calculate the molality, molarity, and mole fraction of the ethylene glycol.
40% means 40 g ethylene glycol/100 g solution.
40 g to moles = 40/molar mass.
Use density to convert 100 g soln to volume, then M = moles/L.
Convert % to m
40g/100 g = 40g glycol/(40g glycol + 60 g water).
Convert 40 g glycol to moles.
Convert 60 g water to kg.
m = moles/kg solvent.
For mole fraction starting with 40% glycol.
moles glycol = 40/molar mass
moles solvent = 60 g/molar mass
mole fraction glycol = moles glycol/total moles.