What is the freezing point (°C) of a solution prepared by dissolving 11.3 g of Ca(NO3)2 in 115 g of water?

Question

molal freezing point depression constant for
water is 1.86 °C/m. (formula weight = 164 g/mol)

Answer 1

Convert the 11.3 g to moles by dividing by the formula mass.

The formula is delta T = km, where k is the freezing depression constant and m is molal. Molal is moles / kg of solvent

In you problem, solve for the delta T

k = 1.86
molal = moles from above / .115 kg.