Assume that the solubility of CaCl2 at this temperature is 70.1 g CaCl2 / 100.0 g of H2O and that the van't Hoff factor for a saturated solution of CaCl2 is i = 2.5. The Kf for water is 1.86C/m. CaCl2 is often used to melt ice on sidewalks.

Could CaCl2 melt ice at -21.0C?

What is the minimum amount of CaCl2 that would be required to melt ice on sidewalks at the above temperature? Use 100.0 g of water as the amount of solvent.