2. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu To View the presentation as a slideshow with effects select “View” on the menu bar and click on “Slide Show.” To advance through the presentation, click the right-arrow key or the space bar. From the resources slide, click on any resource to see a presentation for that resource. From the Chapter menu screen click on any lesson to go directly to that lesson’s presentation. You may exit the slide show at any time by pressing the Esc key. How to Use This Presentation

3. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Chapter Presentation Bellringers Transparencies Standardized Test Prep Math Skills Visual Concepts Resources

4. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Solutions Chapter 7 Table of Contents Section 1 Solutions and Other Mixtures Section 2 How Substances Dissolve Section 3 Solubility and Concentration

5. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 1 Solutions and Other Mixtures Objectives Distinguish between heterogeneous mixtures and homogeneous mixtures. Compare the properties of suspensions, colloids, and solutions. Give examples of solutions that contain solids or gases. Chapter 7

6. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 1 Solutions and Other Mixtures Bellringer Mixtures of solids and liquids are all around us, but are all mixtures classified in the same way? Make a list of at least five mixtures that you have encountered today. List the components of each mixture in general terms, if possible. Remember a mixture can be two solids, a liquid/solid, or two liquids. Example: mud—soil and water, raisin bran cereal—bran flakes and raisins. What similarities or differences in the mixtures on your list could be used to classify all mixtures? Chapter 7

7. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 1 Solutions and Other Mixtures Heterogeneous Mixtures The amount of each substance in different samples of a heterogeneous mixture varies. Example: Any two shovelfuls of dirt from a garden would not be exactly the same. A suspension is a mixture in which large particles of a material are more or less evenly dispersed throughout a liquid or gas. Example: natural orange juice, which contains particles of pulp. Particles in a suspension may settle over time, and may be filtered out. Chapter 7

8. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Suspension Section 1 Solutions and Other Mixtures Chapter 7

9. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 1 Solutions and Other Mixtures Heterogeneous Mixtures, continued Some combinations of liquids will not mix, but will separate spontaneously. Example: Oil and vinegar in salad dressing separates into two layers. Liquids that do not mix with each other are immiscible. One way to separate two immiscible liquids is to carefully pour the less dense liquid off the top. This is called decanting. Chapter 7

10. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Comparing Miscible and Immiscible Liquids Section 1 Solutions and Other Mixtures Chapter 7

11. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 1 Solutions and Other Mixtures Heterogeneous Mixtures, continued A colloid is a mixture consisting of tiny particles that are intermediate in size between those in solutions and those in suspensions and that are suspended in a liquid, solid or gas. Particles in a colloid are too small to settle out. However, particles in a colloid are large enough to scatter light that passes through: this is called the Tyndall effect. Chapter 7

12. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Colloids Section 1 Solutions and Other Mixtures Chapter 7

13. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 1 Solutions and Other Mixtures Heterogeneous Mixtures, continued Examples of familiar materials that are colloids include gelatin desserts, egg whites, and blood plasma. Some immiscible liquids can form colloids. An emulsion is any mixture of two or more immiscible liquids in which one liquid is dispersed in the other. Chapter 7

14. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Emulsions Section 1 Solutions and Other Mixtures Chapter 7

15. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 1 Solutions and Other Mixtures Homogeneous Mixtures Homogeneous mixtures not only look uniform, but are uniform. Example: salt water, which looks uniform even when you examine it under a microscope A solution is a homogeneous mixture of two or more substances uniformly dispersed throughout a single phase. In a solution, the solute is the substance that dissolves in the solvent. The solvent is the substance in which the solute dissolves. Chapter 7

16. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Homogeneous Mixture Section 1 Solutions and Other Mixtures Chapter 7

17. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Solutions Section 1 Solutions and Other Mixtures Chapter 7

18. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Solutes, Solvents, and Solutions Section 1 Solutions and Other Mixtures Chapter 7

19. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 1 Solutions and Other Mixtures Homogeneous Mixtures, continued Miscible liquids mix to form solutions. One way to separate miscible liquids is by distillation, which works when the two miscible liquids have different boiling points. Water is a common solvent, but some liquid solutions contain no water. Example: Fuels such as gasoline, diesel fuel, and kerosene are made from a liquid solution called petroleum, also called crude oil. Components of crude oil are separated by fractional distillation. Chapter 7

20. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Fractional Distillation in Refineries Section 1 Solutions and Other Mixtures Chapter 7

21. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 1 Solutions and Other Mixtures Homogeneous Mixtures, continued Other states of matter can also form solutions. The air you breathe is a solution of nitrogen, oxygen, argon, and other gases. The liquid element mercury dissolves in solid silver to form a solution called an amalgam, which can be used to fill cavities in teeth. An alloy is a solid or liquid mixture of two or more metals. Chapter 7

22. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 How Substances Dissolve Objectives Explain how the polarity of water enables it to dissolve many different substances. Relate the ability of a solvent to dissolve a solute to the relative strengths of forces between molecules. Describe three ways to increase the rate at which a solute dissolves in a solvent. Explain how a solute affects the freezing point and boiling point of a solution. Chapter 7

23. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 How Substances Dissolve Bellringer One mixture you may be familiar with is the one formed when sugar is added to a glass of tea or lemonade. Eventually, the sugar dissolves, and the entire glass tastes sweeter than before. 1. Does the sugar you add to the tea or lemonade dissolve faster before or after ice is added? What happens in each instance? 2. If more sugar is added to the tea or lemonade than will dissolve, what happens to the remaining undissolved sugar? 3. When there is sugar on the bottom of the glass, is the top or bottom of the tea or lemonade sweeter than the rest? 4. What can you do to help the sugar on the bottom of the glass dissolve? Chapter 7

24. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 How Substances Dissolve Water: A Common Solvent Many different substances can dissolve in water. For this reason, water is sometimes called the universal solvent. Water can dissolve ionic compounds because of its structure: it is a polar compound, which is a molecule that has an uneven distribution of electrons. Because they are polar, water molecules attract both the positive and negative ions of an ionic compound. Chapter 7

25. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 How Substances Dissolve Water: A Common Solvent, continued Polar water molecules pull ionic crystals apart, as shown below. Chapter 7 The partially negative oxygen atoms of water molecules attract the positively charged sodium ions. The partially positive hydrogen atoms of water molecules attract the negatively charged chloride ions.

26. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 How Substances Dissolve Water: A Common Solvent, continued Water exhibits hydrogen bonding: the intermolecular force occurring when a hydrogen atom that is bonded to a highly electronegative atom of one molecule is attracted to two unshared electrons of another molecule. Hydrogen bonding determines many of water’s unique properties. Hydrogen bonding enables water to dissolve many molecular compounds, such as sugar. Chapter 7

27. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Hydrogen Bonding Section 2 How Substances Dissolve Chapter 7

28. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 How Substances Dissolve Water: A Common Solvent, continued A rule of thumb in chemistry is that like dissolves like. This rule means that a solvent will dissolve substances that are like the solvent in molecular structure. A nonpolar compound is a compound whose electrons are equally distributed among its atoms. A nonpolar compound usually will not dissolve in water, because its intermolecular forces do not match with those of water. Chapter 7

29. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Like Dissolves Like Section 2 How Substances Dissolve Chapter 7

30. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 How Substances Dissolve The Dissolving Process According to the kinetic theory of matter, water molecules in a glass of tea are always moving. When sugar is poured into the tea, water molecules collide with sugar molecules. Sugar molecules form a solution with water molecules at the surface of the sugar crystals. As layers of sugar molecules leave the crystal, more layers are uncovered and dissolve among the solvent (water) molecules in the same way. Chapter 7

31. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Dissolving Process Section 2 How Substances Dissolve Chapter 7

32. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 How Substances Dissolve The Dissolving Process, continued Solutes with a larger surface area dissolve faster. More solute particles are exposed to the solvent. Stirring or shaking a solution helps the solute dissolve faster. Dissolved solute particles diffuse throughout the solution faster, allowing more solute particles to dissolve. Solutes dissolve faster when the solvent is hot. Collisions occur between solute and solvent particles more frequently and with more energy. Chapter 7

33. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Surface Area Section 2 How Substances Dissolve Chapter 7

34. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Factors Affecting the Rate of Dissolution Section 2 How Substances Dissolve Chapter 7

35. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 How Substances Dissolve The Dissolving Process, continued Solutes affect the physical properties of a solution. Examples: If you dissolve salt in water, it will boil at a higher temperature and freeze at a lower temperature. The coolant mixture of ethylene glycol (antifreeze) with water keeps a car’s radiator fluid from freezing in winter or boiling in summer. Chapter 7

36. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Solubility and Concentration Objectives Explain the meaning of solubility and compare the solubilities of various substances. Describe dilute, concentrated, saturated, and supersaturated solutions. Relate changes in temperature and pressure to changes in solubility of solid and gaseous solutes. Express the concentration of a solution as molarity, and calculate the molarity of a solution given the amount of solute and the volume of the solution. Chapter 7

37. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Solubility and Concentration Bellringer Many solutions can be found in your home. Most of these are not pure solutions, but contain several substances dissolved in a single solvent, such as water. The labels on products often indicate not only the ingredients that are in the solution, but also information about the concentration (the amount of solute in a volume of solution) of the main ingredient. Examine the labels on the next slide, and answer the items that follow. Chapter 7

38. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Solubility and Concentration Bellringer, continued 1. What is the solvent in each solution? 2. What is the solute in each solution? Is there only one solute in each solution? Explain your answer. 3. How would the label for bleach differ for two jugs, one containing 500 mL of bleach and the other containing 1.0 L of bleach? Explain your answer. Chapter 7

39. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Solubility and Concentration Bellringer, continued 4. Would the labels for vinegar and club soda differ for two containers with different total volumes? Explain your answer. 5. Are all of the solutes dissolved solids? Explain your answer. Chapter 7

40. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Solubility and Concentration Solubility in Water Solubility is the maximum amount of a solute that will dissolve in a given quantity of solvent at a given temperature and pressure. Some substances, such as oil, are insoluble in water, meaning they never dissolve. Other substances are said to be soluble in water because they dissolve easily in water. However, there is often a limit to how much of a substance will dissolve. Different substances have different solubilities. Chapter 7

41. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Solubility of a Solid in a Liquid Section 3 Solubility and Concentration Chapter 7

42. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Solubility and Concentration Solubility in Water, continued To express how much of a substance can dissolve in a solvent, you need to use the concentration. Concentration is the amount of a particular substance in a given volume of solution. A solution whose ratio of solute to solvent is relatively high is referred to as concentrated. A solution whose ratio of solute to solvent is relatively low is referred to dilute. Chapter 7

43. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Concentration Section 3 Solubility and Concentration Chapter 7

44. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Solubility and Concentration Solubility in Water, continued An unsaturated solution contains less than the maximum amount of solute that can dissolve. A saturated solution is at a point where no more solute can be dissolved under the same conditions. If you add more solute to a saturated solution, it will simply fall to the bottom of the container. A supersaturated solution holds more dissolved solute than is required to reach equilibrium at a given temperature. To make a supersaturated solution, you raise the temperature of a solution, dissolve more solute, then let the solution cool again. Chapter 7

45. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Solubility and Concentration Solubility in Water, continued Gases can also dissolve in water. Unlike solid solutes, gaseous solutes are less soluble in warmer water than they are in colder water. Example: Soda goes flat quickly at room temperature. The solubility of gases also depends on pressure. Lowered pressure of gas above a solution leads to dissolved gas bubbling out of the solution. Example: When a can of soda is opened, carbon dioxide gas that had been dissolved in the soda bubbles out of solution. Example: If a scuba diver surfaces too quickly, dissolved nitrogen gas in the bloodstream bubbles out of solution, which causes a painful condition called the bends. Chapter 7

46. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Pressure, Temperature, and Solubility of Gases Section 3 Solubility and Concentration Chapter 7

47. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Solubility and Concentration Concentration of Solutions There are several ways to express the concentration of solutions, but one of the most useful ways is by using molarity: moles of dissolved solvent per liter of solution. Chapter 7 Note that molarity is moles per liter of solution, not per liter of solvent. A 1.0 M, which is read as “one molar,” solution of NaCl, contains 1.0 mol of dissolved NaCl in every 1.0 L of solution.

48. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Solubility and Concentration Math Skills Molarity Calculate the molarity of sodium carbonate, Na 2 CO 3, in a solution of 38.6 g of solute in 0.500 L of solution. 1. List the given and unknown values. Given: mass of sodium carbonate = 38.6 g volume of solution = 0.500 L Unknown:molarity, amount of Na 2 CO 3 in 1 L of solution Chapter 7

49. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Solubility and Concentration Math Skills, continued 2. Write the equation for moles Na 2 CO 3 and molarity. Chapter 7

50. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu 3. Find the number of moles of Na 2 CO 3 and calculate molarity. Section 3 Solubility and Concentration Math Skills, continued Chapter 7 molarity of solution = =0.728 M

51. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Solubility and Concentration Concentration of Solutions, continued Other measures of solution concentration can be used. These include: mass percent (grams of solute per 100 g of solution) Ingredients in many food and household products use mass percent. parts per million (grams of solute per 10 6 g of solution) Used for very small concentrations, such as for environmental regulations. Chapter 7

52. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Concept Mapping Section 3 Solubility and Concentration Chapter 7

53. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Understanding Concepts 1. What characteristic of a molecular compound is most likely to cause the compound to be very soluble in water? A.hydrogen content B.low boiling point C.high polarity D.small size Standardized Test Prep Chapter 7

54. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Understanding Concepts 1. What characteristic of a molecular compound is most likely to cause the compound to be very soluble in water? A.hydrogen content B.low boiling point C.high polarity D.small size Standardized Test Prep Chapter 7

55. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Understanding Concepts 2. What factor differentiates a colloid from a suspension? F.Suspensions contain larger particles in solution. G.Colloids have smaller particles that do not settle out. H.A colloid is a type of solution, while a suspension is a type of mixture. I.The solvent in a suspension is polar, while the solvent in a colloid is nonpolar. Standardized Test Prep Chapter 7

56. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Understanding Concepts 2. What factor differentiates a colloid from a suspension? F.Suspensions contain larger particles in solution. G.Colloids have smaller particles that do not settle out. H.A colloid is a type of solution, while a suspension is a type of mixture. I.The solvent in a suspension is polar, while the solvent in a colloid is nonpolar. Standardized Test Prep Chapter 7

57. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Understanding Concepts 3. Adding a crystal to a supersaturated solute causes crystallization of the solute because A.as the added crystal dissolves, it causes the solution to cool. B.the added crystal provides a surface on which the solute can form crystal. C.as the added crystal dissolves, the level of supersaturation becomes too high. D.the added crystal decreases the solubility of the solute molecules, causing them to crystallize. Standardized Test Prep Chapter 7

58. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Understanding Concepts 3. Adding a crystal to a supersaturated solute causes crystallization of the solute because A.as the added crystal dissolves, it causes the solution to cool. B.the added crystal provides a surface on which the solute can form crystal. C.as the added crystal dissolves, the level of supersaturation becomes too high. D.the added crystal decreases the solubility of the solute molecules, causing them to crystallize. Standardized Test Prep Chapter 7

59. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Understanding Concepts 4. When paint thinner is added to latex paint, the mixture quickly separates into two distinct layers, but water mixes into the paint easily. Based on this observation, what can you infer about the type of solvents used in latex paint and in paint thinner? Standardized Test Prep Chapter 7

60. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Understanding Concepts 4. When paint thinner is added to latex paint, the mixture quickly separates into two distinct layers, but water mixes into the paint easily. Based on this observation, what can you infer about the type of solvents used in latex paint and in paint thinner? Answer: The solvent in latex paint has a polar molecule like water. Paint thinner contains nonpolar compounds. Standardized Test Prep Chapter 7

61. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Reading Skills If you rinse greasy hands in water, the grease does not wash off because the molecules of the compounds in grease are nonpolar, while the molecules of water are polar. If you use soap, though, the grease washes away. The molecules of soap are long chains of atoms with a polar end and a nonpolar end. The nonpolar ends surround grease molecules, dissolving them. Then the polar ends of the soap molecules interact with water to make the whole group soluble in water. 5. When the polar end of soap reacts with calcium ions, it forms a salt that is not very soluble in water. How does this explain the observation that soap does not work well in hard water, which contains dissolved calcium ions? Standardized Test Prep Chapter 7

62. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Reading Skills 5. When the polar end of soap reacts with calcium ions, it forms a salt that is not very soluble in water. How does this explain the observation that soap does not work well in hard water, which contains dissolved calcium ions? Answer: The soap molecules react with calcium ions to form a solid that does not dissolve. Therefore the soap is not available to cause nonpolar molecules to dissolve in water. Standardized Test Prep Chapter 7

63. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Interpreting Graphics F.It forms a suspension of small particles. G.The crystal breaks apart into pairs of positive and negative ions. H.Ions separate from one another and interact with water molecules. I.The hydrogen ends of the water molecules surround the cations and the oxygen ends surround the anions. Standardized Test Prep 6. What happens to sodium chloride when it dissolves in water? Chapter 7

64. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Standardized Test Prep Interpreting Graphics Chapter 7 6. What happens to sodium chloride when it dissolves in water? F.It forms a suspension of small particles. G.The crystal breaks apart into pairs of positive and negative ions. H.Ions separate from one another and interact with water molecules. I.The hydrogen ends of the water molecules surround the cations and the oxygen ends surround the anions.