14. Solutions

Calculate the amount of water (in kilograms) that must be added to 12.0 g of urea, (NH₂)₂CO, in the preparation of a 18.3 percent by mass solution. The molar mass of urea, (NH₂)₂CO, is 60.055 g/mol.

A solution was prepared by dissolving 51.0 g of KBr in 310 mL of water. Calculate the mass percent of KBr in the solution.

An aqueous LiNO₂ solution is made using 90.3 g LiNO₂ and diluting it to a total volume of 1.72 L. If the density of the solution is 1.20 g/mL, what is the mass percent of the solution?

Determine the percent sulfuric acid by mass of a 1.37 m aqueous solution of H₂SO₄.

Describe how you would prepare the following solutions from water and the solid solute:

a. 1.85 L of an aqueous solution that is 12.0% KBr by mass and has a density of 1.10 g/mL;

b. 1.20 L of a solution that is 15.0% Pb(NO3)2 by mass and has a density of 1.19 g/mL.

The strength of alcoholic beverages like beer, wine, and spirits is typically expressed in units of alcohol by volume or abv. The abv is calculated by dividing the volume of ethanol (C2H5OH) by the total volume of solution. If the abv of a strong beer like a doppelbock is 8.0%, we can express the concentration in other units from the density of H2O and C2H5OH, which are 1.0 g/mL and 0.79 g/mL at 20°C, respectively. What is the concentration of this beer in

a. mass percent (also known as alcohol by weight or abw),

b. mole percent,

c. molarity,

d. molality?