Calculate the freezing point of an aqueous solution formed by dissolbing 4.22 g of KCl in 25.00 mL of water. Kf for water is (-1.86 degree C/m). Assume density of water is 1.00 g/mL. (Hint: Use the ideal van't Hoff factor, i).

Question

Calculate the freezing point of an aqueous solution formed by dissolbing 4.22 g of KCl in 25.00 mL of water. Kf for water is (-1.86 degree C/m). Assume density of water is 1.00 g/mL. (Hint: Use the ideal van't Hoff factor, i).

Answer 1

mols KCl = grams/molar mass = ?

m = mols/kg solvent. You know kg solvent (0.025kg) and mols KCl. Solve for m.

Then delta T = i*Kf*m
You know m, i for KCl = 2, you know Kf, solve for delta T. Subtract from 0 to find new freezing point.