Solution Stoichiometry WS#1

1. You have a solution of table salt, sodium chloride, in water. What happens to the salt concentration (increases,
decreases, or stays the same) as the solution boils? Draw molecular level pictures to explain your answer.
2. Which of the following diagrams best represents the hydration of NaCl when dissolved in water? The Cl- ion is
larger in size than the Na+ ion. Explain your choice.
3. Differentiate between what happens when the following are dissolved in water:
a. polar solute versus nonpolar solute
b. KF versus C6H12O6
4. Match each name below with the following microscopic pictures of that compound in aqueous solution:
barium nitrate
sodium chloride
potassium carbonate
magnesium sulfate
Which picture best represents HNO3 (aq)?
Why aren’t any of the pictures a good representation of HC2H3O2 (aq)?
5. Using solubility guidelines, predict whether each of the following compounds is soluble or insoluble in water.
What ions, if any, are present upon dissolving the substances in water?
a. PbI2
b. MgBr2
c. (NH4)2CO3
d. Sr(OH)2
e. ZnSO4
6. You are presented with a white solid and told that due to careless labeling, it is not clear if the substance is
barium chloride, lead chloride, or zinc chloride. When you transfer the solid into a beaker and add water, the
solid dissolves to give a clear solution. Next a Na2SO4 (aq) solution is added and a white precipitate forms. What is
the identity of the unknown white solid?
7. Calculate the molarity of each of these solutions:
a. A 5.623 g sample of NaHCO3 is dissolved in enough water to make 250.0 mL of solution.
b. A 184.6 mg sample of potassium dichromate is dissolved in enough water to make 500.0 mL of solution.
c. A 0.1025 g sample of copper metal is dissolved in 35 mL of concentrated HNO3 to form Cu2+ ions, and
then water is added to make a total volume of 200.0 mL (calculate the molarity of Cu2+ ions).
8. A person suffering from hyponatremia has a sodium ion concentration in the blood of 0.118 M and a total blood
volume of 4.6 L. What mass of sodium chloride would need to be added to the blood to bring the sodium ion
concentration up to 0.138 M, assuming no change in blood volume?
9. Describe, using lab equipment and calculations, how you would prepare 250.0 mL of 0.707 M NaNO3 solution.
10. Critical Thinking: Indicate the concentration of each ion present in the solution formed by mixing:
a. 42.0 mL of 0.170 M NaOH and 37.6 mL of 0.400 M NaOH
b. 44.0 mL of 0.100 M Na2SO4 and 25.0 mL of 0.150 M KCl
c. 3.60 grams of KCl in 75.0 mL of 0.250 M CaCl2. Assume that the volumes are additive.