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Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Chapter Presentation Transparencies Lesson Starters Standardized Test PrepVisual Concepts Sample Problems Resources

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Table of Contents Chapter 13 Ions in Aqueous Solutions and Colligative Properties Section 1 Compounds in Aqueous Solutions Section 2 Colligative Properties

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Lesson Starter Compare the composition and arrangement of particles in the solid crystals of CuSO 4 5H 2 O with those in the solution. Chapter 13 Section 1 Compounds in Aqueous Solution

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Objectives Write equations for the dissolution of soluble ionic compounds in water. Predict whether a precipitate will form when solutions of soluble ionic compounds are combined, and write net ionic equations for precipitation reactions. Compare dissociation of ionic compounds with ionization of molecular compounds. Chapter 13 Section 1 Compounds in Aqueous Solution

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Objectives, continued Draw the structure of the hydronium ion, and explain why it is used to represent the hydrogen ion in solution. Distinguish between strong electrolytes and weak electrolytes. Chapter 13 Section 1 Compounds in Aqueous Solution

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Dissociation Dissociation is separation of ions that occurs when an ionic compound dissolves. Chapter 13 Section 1 Compounds in Aqueous Solution 1 mol 1 mol 1 mol 1 mol 1 mol 2 mol

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Dissociation of NaCl Chapter 13 Section 1 Compounds in Aqueous Solution

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Dissociation, continued Sample Problem A Write the equation for the dissolution of aluminum sulfate, Al 2 (SO 4 ) 3, in water. How many moles of aluminum ions and sulfate ions are produced by dissolving 1 mol of aluminum sulfate? What is the total number of moles of ions produced by dissolving 1 mol of aluminum sulfate? Chapter 13 Section 1 Compounds in Aqueous Solution

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Dissociation, continued Sample Problem A Solution Given: amount of solute = 1 mol Al 2 (SO 4 ) 3 solvent identity = water Unknown: a. moles of aluminum ions and sulfate ions b. total number of moles of solute ions produced Solution: Chapter 13 Section 1 Compounds in Aqueous Solution

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Dissociation, continued Precipitation Reactions Although no ionic compound is completely insoluble, compounds of very low solubility can be considered insoluble for most practical purposes. Chapter 13 Section 1 Compounds in Aqueous Solution

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Objectives List four colligative properties, and explain why they are classified as colligative properties. Calculate freezing-point depression, boiling-point elevation, and solution molality of nonelectrolyte solutions. Calculate the expected changes in freezing point and boiling point of an electrolyte solution. Discuss causes of the differences between expected and experimentally observed colligative properties of electrolyte solutions. Chapter 13 Section 2 Colligative Properties of Solutions

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Colligative Properties of Solutions Properties that depend on the concentration of solute particles but not on their identity are called colligative properties. Vapor-Pressure Lowering Freezing-Point Depression Boiling-Point Elevation Osmotic Pressure Chapter 13 Section 2 Colligative Properties of Solutions

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Vapor-Pressure Lowering A nonvolatile substance is one that has little tendency to become a gas under existing conditions. The boiling point and freezing point of a solution differ from those of the pure solvent. A nonvolatile solute raises the boiling point and lowers the freezing point. Chapter 13 Section 2 Colligative Properties of Solutions

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Visual Concepts Click below to watch the Visual Concept. Visual Concept Comparing Volatile and Nonvolatile Liquids Chapter 13

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Chapter 13 Section 2 Colligative Properties of Solutions

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Vapor Pressures of Pure Water and a Water Solution Chapter 13 Section 2 Colligative Properties of Solutions

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Freezing-Point Depression The freezing-point depression, ∆t f, is the difference between the freezing points of the pure solvent and a solution of a nonelectrolyte in that solvent, and it is directly proportional to the molal concentration of the solution. The molal freezing-point constant (K f ) is the freezing-point depression of the solvent in a 1-molal solution of a nonvolatile, nonelectrolyte solute. ∆t f = K f m Chapter 13 Section 2 Colligative Properties of Solutions

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Freezing-Point Depression, continued Molal Freezing-Point and Boiling-Point Constants Chapter 13 Section 2 Colligative Properties of Solutions

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Visual Concepts Click below to watch the Visual Concept. Visual Concept Freezing-Point Depression Chapter 13

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Sample Problem C What is the freezing-point depression of water in a solution of 17.1 g of sucrose, C 12 H 22 O 11, in 200. g of water? What is the actual freezing point of the solution? Chapter 13 Section 2 Colligative Properties of Solutions Freezing-Point Depression, continued

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Sample Problem C Solution Given: solute mass and chemical formula = 17.1 g C 12 H 22 O 11 solvent mass and identity = 200. g water Unknown: a. freezing-point depression b. freezing point of the solution Solution: Chapter 13 Section 2 Colligative Properties of Solutions Freezing-Point Depression, continued

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Sample Problem C Solution, continued Solution: Chapter 13 Section 2 Colligative Properties of Solutions ∆t f = K f m f.p. solution = f.p. solvent + ∆t f Freezing-Point Depression, continued

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Sample Problem C Solution, continued Solution: Chapter 13 Section 2 Colligative Properties of Solutions Freezing-Point Depression, continued

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Sample Problem C Solution, continued Solution: a.∆t f = K f m ∆t f = m × (  1.86°C/m) =  0.465°C Chapter 13 Section 2 Colligative Properties of Solutions Freezing-Point Depression, continued b.f.p. solution = f.p. solvent + ∆t f f.p. solution = 0.000°C + (  0.465°C) =  0.465°C

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Boiling-Point Elevation The boiling-point elevation, ∆t b, is the difference between the boiling points of the pure solvent and a nonelectrolyte solution of that solvent, and it is directly proportional to the molal concentration of the solution. The molal boiling-point constant (K b ) is the boiling- point elevation of the solvent in a 1-molal solution of a nonvolatile, nonelectrolyte solute. ∆t b = K b m Chapter 13 Section 2 Colligative Properties of Solutions

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Visual Concepts Click below to watch the Visual Concept. Visual Concept Boiling-Point Elevation and the Presence of Solutes Chapter 13

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Sample Problem E What is the boiling-point elevation of a solution made from 20.1 g of a nonelectrolyte solute and g of water? The molar mass of the solute is 62.0 g. Chapter 13 Section 2 Colligative Properties of Solutions Boiling-Point Elevation, continued

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Boiling-Point Elevation, continued Sample Problem E Solution Given: solute mass = 20.1 g solute molar mass = 62.0 g solvent mass and identity = g of water Unknown: boiling-point elevation Solution: Chapter 13 Section 2 Colligative Properties of Solutions

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Boiling-Point Elevation, continued Sample Problem E Solution, continued Solution: Chapter 13 Section 2 Colligative Properties of Solutions ∆t b = K b m

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Sample Problem E Solution, continued Solution: Boiling-Point Elevation, continued Chapter 13 Section 2 Colligative Properties of Solutions ∆t b = 0.51°C/m  m = 0.41°C