Question

An aqueous KNO3 solution is made using 73.6 gof KNO3 diluted to a total solution volume of 1.88L . Calculate the mass percent of the solution. (Assume a density of 1.05 g/mL for the solution.)

M= 0.387 (molarity)

m= 0.383 (molality)

Answer 1

First, the reported value of the MM is 101.10 g/mol.

You don't need the molarity or molality to do this, all you need to do is calculate the mass of whole solution, to do that, we need to convert the mass of the salt to volume, and then, find the volume of solvent (which we'll assume is water)

V = m/d ----> V = 73.6 / 1.05 = 70.0952 mL

Vsolvent = 1880 mL - 70.0952 = 1809.90 mL

Assuming that the density of water is 1.00 g/mL, the volume of water = mass of water so:

m solution = 1809.90 + 73.6 = 1883.5 g

% = (73.6/1883.5) * 100

% = 3.91 %

Hope this helps