What would the final freezing point of water be if 3 mol of sugar were added to 1 kg of water (Kf = 1.86C/(mol/kg) for water and i = 1 for sugar)?

Answer 1

molality = mols sugar/kg solvent
Solve for molality

delta T = Kf*m
Solve for delta T and subtract from zero C to find the new freezing point.

Answer 2

-5.58