Question

An aqueous NaCl solution is made using 111 g of NaCl diluted to a total solution volume of 1.10 L . Part A Calculate the molarity of the solution. Express your answer using three significant figures. Part B Calculate the molality of the solution. (Assume a density of 1.08 g/mL for the solution.) Express your answer using two significant figures. Part C Calculate the mass percent of the solution. (Assume a density of 1.08 g/mL for the solution.) Express your answer using three significant figures.

Answer 1

Moles of NaCl = mass/molecular weight

= 111g / (58.44 g/mol)

= 1.899 mol

Volume of solution V = 1.10 L

Part a

Molarity = moles of NaCl / volume

= 1.899 mol / 1.10 L

= 1.73 M

Part b

Mass of solution = volume x density

= 1.10 L x 1.08 g/mL x 1000 mL/L

= 1188 g

Mass of solvent = 1188 - 111 = 1077 g x 1kg/1000g

= 1.077 kg

Molality = moles of NaCl / mass of solvent

= 1.899 mol / 1.077 kg

= 1.8 m

Part c

Mass % of NaCl = mass of NaCl x 100 / mass of solution

= 111 x 100 / 1188

= 9.34 %

Mass % of solvent = 100 - 9.34 = 90.66%