Question

Calculate the anount solution, g, or mL, that contains each of the following amounts of solutes.

A. 20.0 g of KCl from a 10.0% (m/m) KCl solution

B. 55.0 g of NaCl from a 15.0% (m/v) NaCl solution

C. 32.0 g of sodium sulfate from a 3.00 M sodium salfate solution

Answer 1

A) % m/m = (mass of solute / mass of solution) x 100

10.0 = (20.0 / mass of solution) x 100

20 / mass of solution = 0.10

mass of solution = 200

mass of solution = 200 g

B) % m/v = (mass of solute / volume of solution) x 100

15.0 = 55.0 / volume of solution x 100

55.0 / volume of solution = 0.15

volume of solution = 366.7 mL

volume of solution = 366.7 mL

C) Molarity = (W /MW) (1000 / v in mL)

3.00 = (32.0 / 142) (1000 / V)

1000 /V = 13.3

V = 75.20 mL

volume of solution = 75.20 mL