How to do Molarity, Molality and Colligative Properties problems for the following?

Question

1. How many grams of NaOH are dissolved in 450.0 mL of a 0.250 M solution?

2. If a mechanic fills a radiator with 6.5 kg of C2H6O and 1.5 kG of water, what is the molality of the water?

3. The freezing point of an aqueous barium nitrate solution is -2.65 degrees celsius. What's the apparent molal concentration of barium nitrate? (Kf of water is 1.86 degrees celsius/molal)

Answer 1

Moles = M x V = 0.250 x 0.450 L = 0.113

Mass = mol x molar mass = 0.113 x 40 g/mol =4.52 g

Moles C2H6O = 6500 g / 46 g/mol = 141.3

m = moles solute / mass solvent = 141.3 / 1.5 =94.2

Ba(NO3)2 >> Ba2+ + 2 NO3- : we get 3 ions so i = 3

delta T = m x kf x i

2.65 = m x 1.86 x 3

m = 0.474