Unit 3
Wkst 5 - Concentration Units
On a separate sheet of paper, answer the following:
1. Write the equation for the dissociation in water of Al(NO3)3.
2. How many moles of ions are in solution when one mole of cobalt(III) sulfate dissolves?
3. Calculate the mass percent of water in a solution made up of 123 g of NaOH and 289 g of water.
4. Methyl mercuric chloride, CH3HgCl, is a toxic pollutant usually found in waters around industrial
sides. If a sample of 250.0 mL of water (d = 1.00 g/mL) is found to contain 0.200 mg of
CH3HgCl, what is the concentration of methyl mercuric chloride in parts per million?
5. Calculate the mole fractions of tertiary butyl alcohol, C4H9OH, and water, H2O, in a solution made
by adding 100. g of tertiary butyl alcohol to 50.0 g of water.
6. Calculate the molality of a solution made by adding 5.00 g of ethanol, C2H5OH, to 100.0 g of
water H2O.
7. How would you prepare 100.0 mL of a 0.200 M aqueous solution of NaOH from a bottle that is
labeled 0.4871 M?
8. Calculate the molarity of a solution made by dissolving 22.0 g of hydrochloric acid HCl, in 88.0 g
of water, H2O. The density of the resulting solution will be 0.990 g/mL.
9. A solution is prepared by adding 0.200 L of a 1.00 M aqueous solution BaCl2 to 0.300 L of a 1.00
M aqueous solution of NaCl. Calculate the final mol concentrations of Na+, Ba2+, and Cl–,
assuming that both initial solutes are strong electrolytes.
10. An aqueous solution contains sucrose, C12H22O11, in water. The solution has a total mass of 738 g
and the mass percent of sucrose in the solution is 38.4%. Calculate the molality of the solution.
11. What is the mole fraction of bromine in a 0.40 molal solution of Br2 in carbon tetrachloride, CCl4,
solvent?
12. A solution is prepared by mixing 1.00 g ethanol (C2H5OH) with 100.0 g water to give a final
volume of 101 mL. Calculate the molarity, mass percent, mole fraction, and molality of ethanol in
this solution.
13. A 1.37 M solution of citric acid (H3C6H5O7) in water has a density of 1.10 g/mL. Calculate the
mass percent, molality, and mole fraction of the citric acid.
14. Calculate the mole fraction of HCl in an aqueous solution of hydrochloric acid containing 36
percent HCl by weight.
15. Given that the density of a solution of 5.0 g of toluene (C7H8) and 225 g of benzene (C6H6) is
0.876 g/mL, calculate the concentration of the solution in molarity and mass percentage of solute.