The antifreeze in a car is a 50% by weight solution of ethylene glycol, C2H6O2 in a water solvent. Calculate the boiling point and freezing point of this solution.

(For H2O, Kb=0.52 C/m Kf= 1.86 C/m

I can't even find the formula for this in my book, please help :(

1 answer

You need to know the mass of the radiator fluid, take 50% for mass ethylene glycol and 50% H2O.
Then mols glycol = grams/molar mass
molality = mols glycol/kg solvent
delta T = Kf*m
Subtract delta T from 0 for new freezing point.

For boiling point, mols is same, m is same, delta T = Kb*m
Add delta T to 100 for new b.p.