Lesson 3: Wrap Up
Well, that brings us to the end of the lesson; and, as usual, you should take some time to review the lesson, go back over the objectives and make sure that you can do all of the things that are indicated as being necessary for an adequate understanding of solutions.
You have a problem set to complete this week and a lab report to type. The problem set consists of your observations and answers to questions posed in a selection of exercises from the workbook. The lab report will be written about the experiment on the heat of solution of KCl, exercise 17 in your workbook.
Self Quiz
Select the best answer for each of the questions below.
1. Which of the following should be least soluble in water?
a. Ba(NO3)2
b. NaCl
c. CH3OH
d. H2O2
e. O2
2. A white solid is poured into a beaker of water and stirred. The resulting material is a clear, colorless, homogeneous liquid. That material is a(n):
a. unsaturated solution.
b. saturated solution.
c. supersaturated solution.
d. colloidal dispersion.
e. suspension.
3. Calculate the heat of solution given the following information. When 2.0 g of a chemical (formula weight = 40 g/mole) is dissolved in 60 g of water the temperature of the water goes up 8.0°C.
a. -6.0 cal/mole
b. -6.0 kcal/mole
c. -9.6 kcal/mole
d. -240 cal/g
4. Given the following solubility rules, how soluble is ZnSO4?
I. The sulfates of all metals are soluble except those of Pb2+, Hg+, Ba2+, and Ca2+. Silver sulfate is slightly soluble.
II. The sulfides of all metals are insoluble except those of the alkali metals and NH4+.
a. soluble
b. slightly soluble
c. insoluble
5. Refer to the solubility rules above. Will a precipitate form when a solution containing Na+ and S2- is mixed with a solution containing Zn2+ and NO3-?
a. yes
b. no
6. The freezing point of a BaCl2 solution should be _____ that of an equally concentrated NaCl solution.
a. higher than
b. lower than
c. the same as
7. What will happen in an osmosis apparatus containing water on the left side of a semipermeable membrane and sugar water on the right?
a. Water molecules will move to the right.
b. Water molecules will move to the left.
c. Sugar molecules will move to the right.
d. Sugar molecules will move to the left.
8. A chemical which partially dissociates into ions when it dissolves in water is a:
a. nonelectrolyte
b. weak electrolyte
c. strong electrolyte
Answer the following questions.
9. Explain why saturated solutions containing undissolved solute are examples of dynamic equilibrium.
10. Write an equation representing NaCl dissolving in water.
Self Quiz Answers
1. Which of the following should be least soluble in water?
a. Ba(NO3)2
b. NaCl
c. CH3OH
d. H2O2
*e. O2
2. A white solid is poured into a beaker of water and stirred. The resulting material is a clear, colorless, homogeneous liquid. That material is a(n):
*a. unsaturated solution.
b. saturated solution.
c. supersaturated solution.
d. colloidal dispersion.
e. suspension.
3. Calculate the heat of solution given the following information. When 2.0 g of a chemical (formula weight = 40 g/mole) is dissolved in 60 g of water the temperature of the water goes up 8.0°C.
a. -6.0 cal/mole
b. -6.0 kcal/mole
*c. -9.6 kcal/mole
d. -240 cal/g
4. Given the following solubility rules, how soluble is ZnSO4?
I. The sulfates of all metals are soluble except those of Pb2+, Hg+, Ba2+, and Ca2+. Silver sulfate is slightly soluble.
II. The sulfides of all metals are insoluble except those of the alkali metals and NH4+.
*a. soluble
b. slightly soluble
c. insoluble
5. Refer to the solubility rules above. Will a precipitate form when a solution containing Na+ and S2- is mixed with a solution containing Zn2+ and NO3-?
*a. yes
b. no
6. The freezing point of a BaCl2 solution should be _____ that of an equally concentrated NaCl solution.
a. higher than
*b. lower than
c. the same as
7. What will happen in an osmosis apparatus containing water on the left side of a semipermeable membrane and sugar water on the right?
*a. Water molecules will move to the right.
b. Water molecules will move to the left.
c. Sugar molecules will move to the right.
d. Sugar molecules will move to the left.
8. A chemical which partially dissociates into ions when it dissolves in water is a:
a. nonelectrolyte
*b. weak electrolyte
c. strong electrolyte
Answer the following questions.
9. Explain why saturated solutions containing undissolved solute are examples of dynamic equilibrium.
Solute molecules (or ions) continue to dissolve into the solution at the same rate that they crystallize out of the saturated solution.
10. Write an equation representing NaCl dissolving in water.
NaCl(s)
Na+(aq) + Cl-(aq)