1. Chapter 11 Properties of Solutions AP*

2. AP Learning Objectives  LO 1.16 The student can design and/or interpret the results of an experiment regarding the absorption of light to determine the concentration of an absorbing species in a solution. (Sec 11.1)  LO 2.8 The student can draw and/or interpret representations of solutions that show the interactions between the solute and solvent. (Sec 11.1)  LO 2.9 The student is able to create or interpret representations that link the concept of molarity with particle views of solutions. (Sec 11.2)  LO 2.14 The student is able to apply Coulomb’s Law qualitatively (including using representations) to describe the interactions of ions, and the attractions between ions and solvents to explain the factors that contribute to the solubility of ionic compounds. (Sec 11.2)  LO 2.15 The student is able to explain observations regarding the solubility of ionic solids and molecules in water and other solvents on the basis of particle views that include intermolecular interactions and entropic effects. (Sec 11.2- 11.3)

3. AP Learning Objectives  LO 5.10 The student can support the claim about whether a process is a chemical or physical change (or may be classified as both) based on whether the process involves changes in intramolecular versus intermolecular interactions. (Sec 11.2)  LO 6.24 The student can analyze the enthalpic and entropic changes associated with the dissolution of a salt, using particulate level interactions and representations. (Sec 11.2)

4. Section 11.1 Solution Composition AP Learning Objectives, Margin Notes and References  Learning Objectives  LO 1.16 The student can design and/or interpret the results of an experiment regarding the absorption of light to determine the concentration of an absorbing species in a solution.  LO 2.8 The student can draw and/or interpret representations of solutions that show the interactions between the solute and solvent.  AP Margin Notes  Spectral analysis is a common method for analyzing the composition of a solution. See Appendix 3 “Spectral Analysis” for a discussion of the Beer-Lambert law.  Additional AP References  LO 1.16 (see APEC #2, “The Percentage of Copper in Brass”)

5. Section 11.1 Solution Composition Copyright © Cengage Learning. All rights reserved 5 Various Types of Solutions

6. Section 11.1 Solution Composition Copyright © Cengage Learning. All rights reserved 6 Solution Composition

7. Section 11.1 Solution Composition Copyright © Cengage Learning. All rights reserved 7 Molarity

8. Section 11.1 Solution Composition Copyright © Cengage Learning. All rights reserved 8 You have 1.00 mol of sugar in 125.0 mL of solution. Calculate the concentration in units of molarity. 8.00 M EXERCISE!

9. Section 11.1 Solution Composition Copyright © Cengage Learning. All rights reserved 9 You have a 10.0 M sugar solution. What volume of this solution do you need to have 2.00 mol of sugar? 0.200 L EXERCISE!

10. Section 11.1 Solution Composition Copyright © Cengage Learning. All rights reserved 10 Consider separate solutions of NaOH and KCl made by dissolving 100.0 g of each solute in 250.0 mL of solution. Calculate the concentration of each solution in units of molarity. 10.0 M NaOH 5.37 M KCl EXERCISE!

11. Section 11.1 Solution Composition Copyright © Cengage Learning. All rights reserved 11 Mass Percent

12. Section 11.1 Solution Composition Copyright © Cengage Learning. All rights reserved 12 What is the percent-by-mass concentration of glucose in a solution made my dissolving 5.5 g of glucose in 78.2 g of water? 6.6% EXERCISE!

13. Section 11.1 Solution Composition Copyright © Cengage Learning. All rights reserved 13 Mole Fraction

14. Section 11.1 Solution Composition Copyright © Cengage Learning. All rights reserved 14 A solution of phosphoric acid was made by dissolving 8.00 g of H 3 PO 4 in 100.0 mL of water. Calculate the mole fraction of H 3 PO 4. (Assume water has a density of 1.00 g/mL.) 0.0145 EXERCISE!

15. Section 11.1 Solution Composition Copyright © Cengage Learning. All rights reserved 15 Molality

16. Section 11.1 Solution Composition Copyright © Cengage Learning. All rights reserved 16 A solution of phosphoric acid was made by dissolving 8.00 g of H 3 PO 4 in 100.0 mL of water. Calculate the molality of the solution. (Assume water has a density of 1.00 g/mL.) 0.816 m EXERCISE!

17. Section 11.2 The Energies of Solution Formation AP Learning Objectives, Margin Notes and References  Learning Objectives  LO 2.9 The student is able to create or interpret representations that link the concept of molarity with particle views of solutions.  LO 2.14 The student is able to apply Coulomb’s Law qualitatively (including using representations) to describe the interactions of ions, and the attractions between ions and solvents to explain the factors that contribute to the solubility of ionic compounds.  LO 2.15 The student is able to explain observations regarding the solubility of ionic solids and molecules in water and other solvents on the basis of particle views that include intermolecular interactions and entropic effects.  LO 5.10 The student can support the claim about whether a process is a chemical or physical change (or may be classified as both) based on whether the process involves changes in intramolecular versus intermolecular interactions.  LO 6.24 The student can analyze the enthalpic and entropic changes associated with the dissolution of a salt, using particulate level interactions and representations.  Additional AP References  LO 5.10 (see Appendix 7.6, “Distinguishing between Chemical and Physical Changes at the Molecular Level”)  LO 6.24 (see Appendix 7.7, “Intermolecular Forces and Thermodynamics: Why Aren’t All Ionic Solids Soluble in Water?”)

18. Section 11.2 The Energies of Solution Formation Formation of a Liquid Solution 1.Separating the solute into its individual components (expanding the solute). 2.Overcoming intermolecular forces in the solvent to make room for the solute (expanding the solvent). 3.Allowing the solute and solvent to interact to form the solution. Copyright © Cengage Learning. All rights reserved 18

19. Section 11.2 The Energies of Solution Formation Steps in the Dissolving Process Copyright © Cengage Learning. All rights reserved 19

20. Section 11.2 The Energies of Solution Formation Steps in the Dissolving Process  Steps 1 and 2 require energy, since forces must be overcome to expand the solute and solvent.  Step 3 usually releases energy.  Steps 1 and 2 are endothermic, and step 3 is often exothermic. Copyright © Cengage Learning. All rights reserved 20

21. Section 11.2 The Energies of Solution Formation Enthalpy (Heat) of Solution  Enthalpy change associated with the formation of the solution is the sum of the ΔH values for the steps: ΔH soln = ΔH 1 + ΔH 2 + ΔH 3  ΔH soln may have a positive sign (energy absorbed) or a negative sign (energy released). Copyright © Cengage Learning. All rights reserved 21

22. Section 11.2 The Energies of Solution Formation Enthalpy (Heat) of Solution Copyright © Cengage Learning. All rights reserved 22

23. Section 11.2 The Energies of Solution Formation Explain why water and oil (a long chain hydrocarbon) do not mix. In your explanation, be sure to address how ΔH plays a role. Copyright © Cengage Learning. All rights reserved 23 CONCEPT CHECK!

24. Section 11.2 The Energies of Solution Formation The Energy Terms for Various Types of Solutes and Solvents Copyright © Cengage Learning. All rights reserved 24 ΔH1ΔH1 ΔH2ΔH2 ΔH3ΔH3 ΔH soln Outcome Polar solute, polar solventLarge Large, negativeSmallSolution forms Nonpolar solute, polar solventSmallLargeSmallLarge, positiveNo solution forms Nonpolar solute, nonpolar solvent Small Solution forms Polar solute, nonpolar solventLargeSmall Large, positiveNo solution forms

25. Section 11.2 The Energies of Solution Formation In General  One factor that favors a process is an increase in probability of the state when the solute and solvent are mixed.  Processes that require large amounts of energy tend not to occur.  Overall, remember that “like dissolves like”. Copyright © Cengage Learning. All rights reserved 25

26. Section 11.3 Factors Affecting Solubility AP Learning Objectives, Margin Notes and References  Learning Objectives  LO 2.15 The student is able to explain observations regarding the solubility of ionic solids and molecules in water and other solvents on the basis of particle views that include intermolecular interactions and entropic effects.

27. Section 11.3 Factors Affecting Solubility  Structure Effects:  Polarity  Pressure Effects:  Henry’s law  Temperature Effects:  Affecting aqueous solutions Copyright © Cengage Learning. All rights reserved 27

28. Section 11.3 Factors Affecting Solubility Structure Effects  Hydrophobic (water fearing)  Non-polar substances  Hydrophilic (water loving)  Polar substances Copyright © Cengage Learning. All rights reserved 28

29. Section 11.3 Factors Affecting Solubility Pressure Effects  Little effect on solubility of solids or liquids  Henry’s law:C = kP C = concentration of dissolved gas k = constant P =partial pressure of gas solute above the solution  Amount of gas dissolved in a solution is directly proportional to the pressure of the gas above the solution. Copyright © Cengage Learning. All rights reserved 29

30. Section 11.3 Factors Affecting Solubility A Gaseous Solute Copyright © Cengage Learning. All rights reserved 30

31. Section 11.3 Factors Affecting Solubility Temperature Effects (for Aqueous Solutions)  Although the solubility of most solids in water increases with temperature, the solubilities of some substances decrease with increasing temperature.  Predicting temperature dependence of solubility is very difficult.  Solubility of a gas in solvent typically decreases with increasing temperature. Copyright © Cengage Learning. All rights reserved 31

32. Section 11.3 Factors Affecting Solubility The Solubilities of Several Solids as a Function of Temperature Copyright © Cengage Learning. All rights reserved 32

33. Section 11.3 Factors Affecting Solubility The Solubilities of Several Gases in Water Copyright © Cengage Learning. All rights reserved 33