Unit 15
Solutions
Section 15.1
Key Terms
Solution
Solvent
Solute
Aqueous solution
Saturated
Unsaturated
Supersaturated
Concentrated
Dilute
Questions
1. Draw a molecular (microscopic) level picture to show how salt and sugar look when dissolved in water.
2. Determine the number of moles of each type of ion in solution when 1 mole of each of the following dissolves in water:
a. sodium sulfate
b. ammonium acetate
c. calcium chloride
d. copper(II) sulfate
3. Chemists often say “like dissolves like.” What does this mean?
4. Why does water by itself not dissolve a grease stain?
5. Can dilute solution also be saturated? Explain.
6. Increasing the number of collisions between solid and solvent particles increases the rate at which a solid dissolves. Explain how stirring, increasing surface area, and heating increase the number of collisions.
Section 15.2
Describing Solution Composition
Key Terms
Mass percent
Molarity (M)
Standard solution
Dilution

Questions
1. Vinegar is made by adding 33 g of acetic acid to 625 g of water. What is the percent by mass of acetic acid in this solution of vinegar?
2. Assuming the density of vinegar is 1.0 g/mL, what is the molarity of vinegar? (Use the percent by mass of acetic acid in vinegar from question 1.) The molar mass of acetic acid is 60.05 g/mol.
3. A solution is labeled “0.450 M magnesium nitrate.” Calculate the concentration of each ion present in solution.
4. Calculate the number of moles of KOH in 150.0 mL of a 0.500 M KOH solution.
5. If 4.25 g of CaBr
2
is dissolved in enough water to make 125 mL of solution, what is the molarity of the solution?
6. What is the key idea to remember when working with the dilution of a solution?
7. Calculate the new concentration when 50.0 mL of water is added to 725.0 mL of 1.25 M NaCl.
Section 15.3
Properties of Solution
Key Terms
Neutralization reaction
Equivalent of an acid
Equivalent of a base
Equivalent weight
Colligative property
Questions
1. The key to solving stoichiometry problems is the mole. How do we find the number of moles when solutions are mixed to produce a reaction?
2. How many milliliters of 0.10 M Pb(NO
3
)
2
solution are required to precipitate all the lead, as PbI
2
, from
125.0 mL of 0.1 M NaI solution.
3. Determine the mass of Ag
2
CrO
4
produced when 100.0 mL of 0.500 M silver nitrate is added to 100.0 mL of 0.500 M potassium chromate.
4. Once you have determined moles of H + or OH in a neutralization reaction how can you find the volume of the substance? What is the critical information you need to determine volume?
5. What volume of 0.25 M NaOH is required to neutralize 125.0 mL of 0.15 M HCl?
6. How is normality different from molarity?
7. Is a 1 M H
2
SO
4
solution the same as a 1 NH
2
SO
4 solution? Explain.
8. Other than for taste, why is salt added to water when cooking pasta?