What is the mass of NaCl required to make 140 grams of a 12% solution of NaCl in water?

A. 12 grams

B. 14 grams

C. 17 grams

D. 18 grams

C. 17 grams.

Explanation:

∵ mass % = [mass of solute/mass of solution] x 100.

mass of solute (NaCl) = ? g & mass of solution = 140.0 g.

∴ mass of NaCl = (mass %) (mass of solution) / 100 = (12.0) (140.0) / 100 = 16.80 g ≅ 17.0 g.

mass of NaCl required = 17 grams

Explanation:

Mass% = mass of solute X 100 / total mass of solution

mass% = mass of solute X 100 / mass of solute + mass of solvent

given:

Mass of solution = 140 grams

mass % = 12%

Putting values

12 = mass of NaCl X 100 / 140

mass of NaCl = 12 X 140 / 100 = 16.8 grams

mass of NaCl required = 17 grams