posted by danielle .
Automotive antifreeze consists of ethylene glycol, C2H6O2, a nonvolatile electrolyte. Calculate the boiling point and freezing point of a 25.0 mass percent of ethylene glycol in solution.
25% by mass means 25 g ethylene glycol + 75 g water (assuming the density of ethylene glycol is 1.0 g/mL which I doubt). If you have a density, you can change those numbers.
Then delta T = Kf*molality
molality = moles/kg solvent.
moles = g/molar mass.
Freezing point part is done the same way but use Kf instead of Kb.
Kf is 1.86 for water.
Kb is 0.51 for water.