An aqueous KNO3 solution is made using 72.5 grams of KNO3 diluted to a total solution volume of 2.00 liters. If the molarity of the solution is .359 M and the molality of the solution is .354, what is the mass percent of the solution?

Answer 1

M = moles/L soln
moles KNO3 = grams KNO3/molar mass = 72.5/101.1/2L soln = 0.359 to confirm the 0.359 stated in the problem.

m = mols/kg solven
0.7171/kg solvent. We must calculate the kg solvent.
0.354 = 0.7171/kg solvent and
kg solvent = 0.7171/0.354 = about 2.026 kg. (Confirm: 0.7171/2.026kg = 0.354.

The total mass of the solution, therefore, is 72.5 g + 2,026 g = 2098.5.
%soln w/w = (g KNO3/total mass)*100 =?

m = moles/kg solvent