how many grams of methanol must be added to 5.00kg of water to lower its freezing point to -12.0 degrees C? for each mole of solute the freezing point of 1kg of water is lowered 1.86 degrees C?

Question

how many grams of methanol must be added to 5.00kg of water to lower its freezing point to -12.0 degrees C?  for each mole of solute the freezing point of 1kg of water is lowered 1.86 degrees C?

DrBob222 · Answer

You want delta T to be 12.5 C.
delta T = Kf*m
You know delta T and Kf, solve for molality (m).
m = mols CH3OH/kg solvent. You know kg solvent and m, solve for mols CH3OH.
Then mols CH3OH = grams/molar mass. YOu know molar mass and mols, solve for grams.

Anonymous 2 · Answer

Hello DrBob222, thank you for trying to help explain it, but unfortunately it was not helpful.