You have an aqueous solution of NaCl that has a freezing point of -5.25 C. What mass (in grams) of NaCl must be added to 1000 g of this solution to lower the freezing point to -12.00 C? (Assume a van't Hoff factor of 1.9 for NaCl). (Kf for water is 1.86 Ckg/mol).