What mass of salt(NaCl)should you add to 1.20 L of water in an ice cream maker to make a solution that freezes at -10.4∘C?

Answer 1

delta T = i*Kf*m
You have delta T = 10.4
i is the van't Hoff factor which is 2 for NaCl.
Kf = 1.86 for water. Solve for m.
Then m is molality = mols NaCl/kg solvent. You have kg solvent. Solve for mols.
Then mols = grams/molar mass. You have mols and molar mass NaCl; solve for grams NaCl.