You want to lower the freezing point of a salt solution to -19 C by adding sodium

You want to lower the freezing point of a salt solution to -19 ⁰C by adding sodium chloride to water.

a) Determine the mass of sodium chloride that you must add, per kilogram of water.

b) Calculate the concentration of this solution, in molarity, given that it has a density of 1.18 g/ml.