Question

A 20.0 mL sample of a NaCl solution has a mass of 21.040g. After the solution is evaporated to dryness, the dry salt residue has a mass of 4.348g. Calculate the following concentrations for the NaCl solution. (Molarity)

Answer 1

Mass NaCl = 4.348
Mass solution = 21.040 - 4.348 = 16.692
mass/mass % =
4.348/16.692
= 26%
mass/vol % =
21.7%
Molecular mass of NaCl = 58.5
Moles of NaCl = 0.074
Volume of solution = 0.02 L
Molarity = 3.7 mol/Liter