AP CHEMISTRY: CHAPTER 11
Properties of Solutions
Most of the chemistry in the rest of the text occurs in water solutions. This chapter reviews the material introduced in
Chapter 4. Understanding the structure and properties of solutions is the necessary background for the study of water
based equilibrium, acid-base chemistry, and redox. You will become familiar with the different definitions of
concentration. It is important that you learn to change from one set of concentration units to another. The
mathematics of colligative properties will be discussed. Note the similarities between the different equations which you
will summarize on a dittoed table.
CA State Standards: 6.a-f
Concepts:
1. How can a supersaturated solution be prepared?
2. Define mol fraction, molality, and molarity. Compare and contrast the three units of concentration
explaining how they are alike and how they differ.
3. What are the conditions under which molarity and molality are the same?
4. What does the phrase "like dissolves like" mean? Define it in scientific terms. What are the main factors
affecting solubility?
5. How does raising the temperature of a solvent affect the solubility of most solids? Most gases?
6. If a solid or a nonvolatile solute is added to a solution, the boiling point is elevated; explain why in terms
of molecular motions rather than vapor pressure.
7. Explain why adding a volatile solute usually lowers the boiling point of a solution.
8. Explain the solubility principle involved in the death of nearly 2000 people in the Cameroon.
9. The freezing point of a solution is lower than that of a pure solvent. Does it matter whether the solute is
volatile or not? Defend your position by explaining the molecular level mechanism of freezing point
lowering.
10. What sorts of substances dissolve best in water?
11. Explain the process of hydration. What happens when an ionic solid is hydrated? Why does water work
well as a hydrating agent?
12. Colligative laws for electrolyte solutions are the same as those for non-electrolytes except for one factor.
Identify the factor
13. How can "i" be used to determine the extent of ionization of a solution?
14. How does "ionic pair formation" occur? Of what does it consist? What effect does it have on
conductivity and colligative properties?
15. Industrial plants may pollute nearby lakes and rivers thermally. Fish may die from this environmental
pollution. Does this mean that the fish are cooked? Explain.
16. Use Le Chatelier's principle and gas solubility principles to explain the formation of boiler scale.
17. Explain the generation of electricity by a solar pond. Why is this suggested as a renewable energy
alternative?
Questions and Exercises:
Note: Solution Review at beginning of exercises is designed to review the calculations covered in Chapter 4,
Sections 4.1-4.3. Review this material if you feel "rusty" on solutions.
15,17,21,31,30,33,37,39,40,41,45,49,53,57,63,69,72,83,94
Lab Work: Experiment 22 (ditto) -- Colligative Properties: Formula Weight Determination
Name__________________________
SUMMARY TABLE FOR CHAPTER 11 CALCULATIONS
Complete the table below and turn it in with your homework problems.
The osmotic pressure law, another colligative property law, is Π=MRT. Notice that if all experiments are carried out at
room temperature, the RT term becomes constant (call it R'). This colligative law can then be written =MR'. As you fill
in the following table, notice that all the colligative property laws have basically the same format. Under comments,
note any special conditions such as: units for the concentration term, special characteristics for the constant (a just
illustrated) or alternative forms of the law (Raoult's Law, for example is listed twice).
In the last column, rewrite each of the equations in a form that includes the molecular weight (MM) of the solute as a
term in the equation to show how each equation can be used to find the molecular weight of an unknown.
Name of
Law
"Unknown
Quantity" =
=
(Concentration )
Raoult's
P1
(X1)
Raoult's
ΔP1
=
(X2)
Boiling
Point
ΔTbp =
(m)
Freezing
Point
ΔTfp =
Osmotic
Pressure
Π=
(Constant)
(P1o)
(P1o)
Comments
Concentration is in moles of 1
Total Moles
X1 is mol fraction of solvent.
Constant is original pressure.
X2 is mol fraction of solute.
Equation with
MM