Question

How much ethylalcohol must be added to 1litre of water so that the solution will freeze at 14 farenite, kf of wa

ter is 1.86 c/mol

Answer 1

14 F. Convert to C. (F-32)*5/9 = C

delta T = Kf*molality
Substitute delta T and Kf. Solve for m.
m = mols/kg solvent.
You know m and kg H2O. Solve for mols.
mols = grams/molar mass. You know mols and molar mass, solve for grams.