CHM 2046C Module 8ii Homework Packet –Chapter 12  Name: _______________

Please complete the following homework sections before you attempt the exam. This is homework. You grade it. This completed packet is due the day of the exam. You must show all work. Any mathematical type problem application must show work. No credit for just writing the answer. No credit for a section if the sample problem is shown and you leave any additional problems which do not show the answer blank.


Module Eight II: Solutions and Their Properties Jespersen Chapter 12

_____N. (01) Units of Concentration/definitions Section 12.5

_____O. (01) Concentration Calculations: molality, % by weight, mole fraction Sect12.5

_____P. (01) Enthalpy of Solution Calculation Section 12.2

_____Q. (01) Factors Affective Solubility Section 12.2-12.3

_____Q1(01) Henry’s Law Calculation Section 12.4

_____R. (01) Colligative Properties Problem: Raoult's Law Section 12.6

_____S. (01) Colligative Properties Problems: Boiling Point Elevation Section 12.6

_____T. (01) Colligative Properties Problems: Freezing Point Depression Section 12.6

_____U. (01) Colligative Properties Problems: Molar Mass Determination Section 12.6

_____V. (01) Colligative Properties Problems: Osmotic Pressure Section 12.6

_____W.(01) Colligative Properties of ionic Solutions Section 12.6

_____X. (01) Discussion Questions Chapter 12

_____Z. (00) Key Terms Chapter 12


______(12) Total M-8ii Homework Packet


Part N: Units of Concentration    1 point


Show the unit factor for each of the following and also label each unit as solute, Solvent or Solution:


1,  Molality





2.  Mole Fraction





3. Weight %





4. Molarity




5. Parts Per Million 




Reading Reference: Section 12.5
Summary Shown in Table 12.3 page 593

Module Eight Part II: Solutions Chapter 12




Part O: Concentration Calculations   1 point


You want to prepare an aqueous solution of glycerol, C3H5(OH)3  in which the mole fraction of the solute is 0.093. What mass of glycerol must you add to 425 g of water to make the solution?

What is the molality of the solution?

What is the mass percent?


Mass of Glycerol




















Mass Percent

















Reading Reference: Section 12.5

% Composition: See Example 12.2 page 589;  Work Practice Exercises 12.9/12.10 Page 590
Molal Concentration: See Example 12.3 p591; Work Practice Exercises 12.11/12.12 page 591
Mole Fraction: See Example 12.4 p 592; Work Practice Exercises 12.13/12.14 page 593

/Mole %: See Example 12.5page 594; Work Practice Exercises 12.15/12.16 page 594

End of Chapter: Problems #12.57-#12.72 page 621





Module Eight Part II: Solutions Chapter 12

Part P: Enthalpy of Solution Calculation    1 point

Use the following data to calculate the enthalpy of solution of sodium perchlorate, NaClO4(Solids in Liquids):

               Hºf (s) = -382.9 kJ/mol

               Hºf (aq, 1 m) = -369.5 kJ/mol
See Figure 12.5 page 581. Summary:
Hºsolution = ∑ [∆Hºf (product) ] - ∑ [∆Hºf (reactant) ]  or Hºsolution =  Hºf (aq, 1 m) - ∆Hºf (s)













Reading Reference: Section 12.2  (See Table 12.1 Page 581)
Note Figure 12.6 Page 582 for liquids and liquids  and Figure 12.7 Enthalpy change for an Ideal Solution 


Part Q: Factors Affecting Solubility    5 points


Describe the two external factors which affect the solubility of gases in liquids, while

contrast the same factors with solubility of solids in liquids and liquids in liquids..








State Henry’s Law





Reading Reference: Section 12.4





Part Q1: Henry’s Law Calculation    1 point

The solubility of methane, the chief component of natural gas, in water at 20.0oC and 1.0 atm pressure is 0.025g/L. What is the solubility in water at 1.5 atm and 20.0oC?







Reading Reference: Section 12.4.
See Example 12.1 page 587  Work Practice Exercises 12.7/12.8 page 588
End of Chapter Problems: 12.51-12.56 pages 620-621






Module Eight Part II: Solutions Jespersen Chapter 12

Part R: Colligative Properties: Raoult’s Law    1 point

Nonvolatile solute: (5 points)       

A 55 gram sample of ethylene glycol HOCH2CH2OH , is dissolved in 500.0 g of water.

The vapor pressure of water at 32 oC is 35.7 mm Hg. What is the vapor pressure of the

water-ethylene glycol solution at 32 oC? (Ethylene Glycol is nonvolatile.)

See Example 12.6 page 596; work Practice Exercise 12.17/12.18 page 597










Solutions with a volatile solute (5 points)

What is the vapor pressure in mmHg of a solution prepared by dissolving 25.0 grams of ethyl alcohol (C2H5OH) in 100 grams of water at 25oC? (The vapor pressure of pure water is 23.8 mmHg and the vapor pressure of the ethyl alcohol is 61.2 mmHg at 25oC.)

See Example 12.7 page 598; work Practice Exercise 12.19/12.20 page 599







Reading Reference: Section 12.6  pages 596-599
End of Chapter Problems: #12.73-#12.80




Part S: Boiling Point Elevation Problem  1 point


A solution of glycerol, C3H5(OH)3, in 735 g of water has a boiling point of 104.4 oC at a pressure of 760 mm Hg.

(Assume the solute to be a nonvolatile solute and the kbp of water is + 0.52 oC/m)

What is the mass of glycerol in the solution?









What is the mole fraction of the SOLUTE?








Reading Reference: Section 12.6 Pages 599-602 See Table 12.4 page 601 for Kb and Kf values
Work Practice Exercises 12.21/12.22pages 601-602; End of Chapter #12.82 page 622





Module Eight Part II: Solutions Jespersen Chapter 12    

Part T: Freezing Point Depression Problem   1 point


What mass of ethylene glycol, HOCH2CH2OH, must be added to 6.50 Kg of water to lower the freezing point of the water from 0.0 to -10.0 oC. (This is supersize car radiator)

(Assume the solute to be a nonvolatile solute and the kfp of water is – 1.86 oC/m)











Reading Reference: Section 12.6 Pages 599-602. See Table 12.4 page 601 for Kb and Kf values
See Example 12.8 page 601; End of Chapter #12.81 page 622





Part U: Molar Mass Determination Problem    5 points


An aqueous solution contains 0.180 g of an unknown, non volatile/non ionic solute in 50.0 g of water. The solution freezes at -0.040oC. What is the molar mass of the solute?














Reading Reference: Section 12.6 Pages 602-603. See Table 12.4 page 601 for Kb and Kf values
See Example 12.9 page 602; Work Practice Exercises12.23/12.24 page 603; End of Chapter #12.83-6 page 622





Part V: Osmotic Pressure Problem   1 point


Estimate the osmotic pressure of human blood at 37 oC. Assume blood is isotonic with 0.16 M NaCl solution, and assume the van’t Hoff factor i is 1.9 for NaCl. Remember the NaCl is ionic.

∏= cRT i











Reading Reference: Section 12.6 Pages 603-609.
See Example 12.10 page 607; Work Practice Exercises 12.25/26 Page 607;
End of Chapter #12.91-#12.92 page 622
See Example 12.11 page 608; Work Practice Exercises 12.27/12.28 page 609





Part W: Colligative Properties of ionic Solutions   1 point


Both Sodium Chloride and Calcium chloride are used to melt ice on roads and sidewalks during the winter up North. What is the expected freezing point of a 0.50 m solution of NaCl?
of a 0.50m solution of CaCl2? Assume ideal solution behavior




















How many grams of Aluminum chloride would be dissolved in 0.250 L of water to give a solution that has a vapor pressure of 36.2 torre at 36oC? Assume an ideal solution.

























Reading Reference: Section 12.6 Pages 609.
See Example 12.12 page 609; Work Practice Exercises 12.29/12.30 Page 610;
End of Chapter #12.89-#12.96 page 622




Part X: Discussion Questions Chapter 12    1 point

Write the answers to:


1. What is an ideal solution?





2. Why does the freezing point decrease, while the boiling point increases of a solvent upon addition of a solute to a solvent?







3. Describe the terms isotonic, hypotonic, and hypertonic.









4. Summarize the different types of colloids and give an example of each.(see Table 12.6 page 615)











5. What is a colloidal dispersion?











6. Why is ammonia much more soluble than oxygen in water?






7. Define the terms miscible and immiscible.










8. What two factors are largely responsible for determining the magnitude and sign of the enthalpy of solution?











9. Describe how temperature and pressure affect the solubility of a gas.












10. What is Henry’s law?













Reading Reference: Chapter 12

Look at Review Questions 12.1-12.48 pages 619-620 for additional discussion questions.





Module Eight Part II: Solutions Chapter 12


 Part Z: Vocabulary Chapter 12                                          0 point


 1. ________________  A colloid in which either a liquid or solid is dispersed in a gas


 2. _________________ A solution of higher solute concentration than a cell


3. _________________ A colloid in which a liquid is dispersed in a solid


4. _________________ A colloid in which a solid is dispersed in another solid


5. _________________ A colloid in which a gas dispersed in either a liquid or solid


6. _________________ A colloid formed when the dispersing medium and the dispersed state are both liquids


7. _________________ An intermediate state between a solution and a suspension.  The dispensed phase is dispersed throughout the dispersing medium, but the particles are larger than in a solution.  Unlike a suspension, the particles do not settle out


8. _________________ The movement of solvent molecules through a semipermeable membrane from a region of lower solute concentration into a region of higher solute concentration



9. __________________ A solution in which the concentration of the solute equals its solubility


10. _________________ The particles of a material are temporarily dispersed in a solvent as large aggregates but these particles settle out with time and are visible. This is an example of a heterogeneous mixture, and milk of magnesia is an example.




Give is a word and its definition of a chapter 12 vocabulary terms not in the above 10 questions:


Colligative Property; Ideal Solution; Hypotonic Solution; Isotonic Solution;