1. Back Bires, 2010 Slide 1 Chapter 13, (14): Mixtures and Aqueous Solutions What are they? Where do we find them? How do we describe them? We use solutions all the time

2. Back Bires, 2010 Slide 2 Soluble and Insoluble Soluble means: able to be dissolved. Soluble means: able to be dissolved. Ionic solids (made of cation and anion) dissociate into their ions in water. Ionic solids (made of cation and anion) dissociate into their ions in water. Covalent solids (like sugar) dissolve when they are relatively polar. Covalent solids (like sugar) dissolve when they are relatively polar. The dissolved particles cannot be easily seen or separated from the solution. The dissolved particles cannot be easily seen or separated from the solution. “Like dissolves like” “Like dissolves like” Alloys are solutions of metals! Alloys are solutions of metals! Solubility depends upon temperature… Solubility depends upon temperature…

3. Back Bires, 2010 Slide 3 Increasing temperature increases the solubility of solids in liquids Increasing temperature decreases the solubility of gasses in liquids! …

4. Back Bires, 2010 Slide 4 Gasses in liquids In addition to cold temperatures, high pressures increase solubility of gasses in liquids. In addition to cold temperatures, high pressures increase solubility of gasses in liquids. Henry’s Law: Henry’s Law: –solubility of a gas in a liquid increases with increasing pressure of that gas above the liquid.

5. Back Bires, 2010 Slide 5Saturation Saturated Solution Saturated Solution –solution has as much solute as it will allow Unsaturated Solution Unsaturated Solution –more solute can dissolve into solution Supersaturated Solution Supersaturated Solution –too much solute in solution-some will come out We express the quantitative amount of solute in a solution with concentration … (later) We express the quantitative amount of solute in a solution with concentration … (later)

6. Back Bires, 2010 Slide 6 Parts of a solution The dissolving medium is the solvent (what does the dissolving…the dissolver) The dissolving medium is the solvent (what does the dissolving…the dissolver) The dissolved substance is the solute (what gets dissolved…the dissolvey) The dissolved substance is the solute (what gets dissolved…the dissolvey) The solute and solvent together form the solution. The solute and solvent together form the solution. Solvents and solutes can be any phase. Solvents and solutes can be any phase. solution

7. Back Bires, 2010 Slide 7 Special types of mixtures - Suspensions Suspensions Suspensions –mixtures where the solutes particles are very large, so they don’t completely dissolve into their solvent. Solute particles will settle out of the solution if left undisturbed. – this creates two phases. Solute particles will settle out of the solution if left undisturbed. – this creates two phases. Muddy water and Italian salad dressing are good examples of suspensions. Muddy water and Italian salad dressing are good examples of suspensions.

8. Back Bires, 2010 Slide 8 Special types of mixtures - Colloids Colloids Colloids –mixtures where the solute particle is smaller than particles in a suspension, but not small enough to dissolve. Colloids have two phases: Colloids have two phases: Dispersed phase – the solute Dispersed phase – the solute Dispersing medium – the solvent. Dispersing medium – the solvent. Mayonnaise and hair gel are good examples of colloids. Mayonnaise and hair gel are good examples of colloids. There are 7 types of colloids, found on page 398… There are 7 types of colloids, found on page 398…

9. Back Bires, 2010 Slide 9 7 Types of Colloids Page 398 Two groups of colloids: Heterogeneous colloids – two phases are clearly seen Homogeneous colloids – appears to be one phase Colloid Type PhasesExample Sol solid in liquid, liquid substance Paint Gel solid in liquid, solid substance Gelatin Foam gas in liquid Whipped cream Liquid Emulsion liquid in liquid Milk, mayonnaise Solid Emulsion liquid in solid Cheese, butter Solid Aerosol solid in gas Smoke Liquid Aerosol liquid in gas Clouds, fog

10. Back Bires, 2010 Slide 10 The Tyndall Effect The Tyndall effect allows us to distinguish between solutions, colloids, and suspensions. The Tyndall effect allows us to distinguish between solutions, colloids, and suspensions. It works by shining a beam of light into the mixture. If… It works by shining a beam of light into the mixture. If… Light is blocked at entry into the mixture Light is blocked at entry into the mixture –the mixture is a suspension. Light passes through unobstructed Light passes through unobstructed –the mixture is a solution. Light passes, but the beam can be seen in the mixture Light passes, but the beam can be seen in the mixture –the mixture is a colloid. John Tyndall, Brittish, c1860

11. Back Bires, 2010 Slide 11Electrolytes Electrolytes Electrolytes –Solutions that conduct electricity. Ionic solutions are electrolytes. Ionic solutions are electrolytes. Covalent solutions are nonelectrolytes. Covalent solutions are nonelectrolytes. Is saltwater (NaCl in water) an electrolyte? Is saltwater (NaCl in water) an electrolyte? Is sugar water (C 6 H 12 O 6 in water) an electrolyte? Is sugar water (C 6 H 12 O 6 in water) an electrolyte? Conductivity tester Conductivity tester –can tell us if a solution is an electrolyte, and sometimes, how strong an electrolyte is.

12. Back Bires, 2010 Slide 12 Concentration - Molarity Concentration Concentration –the quantitative amount of solute present in a solution Molarity (M) – moles/liter Molarity (M) – moles/liter –number of moles solute in liters of solution We can use the T-chart method to find moles of solute present. We can use the T-chart method to find moles of solute present.

13. Back Bires, 2010 Slide 13 Try these Molarity exercises What is the concentration [in Molarity] when 3.0 moles of NaCl are dissolved in 2.0 Liters of water? What is the concentration [in Molarity] when 3.0 moles of NaCl are dissolved in 2.0 Liters of water? How much (in liters) of a 0.10 M solution do you need to get 2.0 moles of solute? How much (in liters) of a 0.10 M solution do you need to get 2.0 moles of solute? How many moles of NaOH are present in 300.mL of a 1.0M solution? How many moles of NaOH are present in 300.mL of a 1.0M solution? How many grams of HCl are found in 100mL of a 2.0M solution? How many grams of HCl are found in 100mL of a 2.0M solution? What mass of NaOH is required to be dissolve in 250mL of water to make a 2.8M solution? What mass of NaOH is required to be dissolve in 250mL of water to make a 2.8M solution? 1.5 M “molar” 20 L.30 moles 7.3 grams 28 g NaOH

14. Back Bires, 2010 Slide 14 Concentration - Molality Molality (m) – moles/kilogram – number of moles solute in kilogram of solvent. Molality (m) – moles/kilogram – number of moles solute in kilogram of solvent. used less often, but important for colligative properties used less often, but important for colligative properties

15. Back Bires, 2010 Slide 15 Try these molality exercises What is the concentration in molality when 2 moles of NaCl are dissolved in 4kg of water? What is the concentration in molality when 2 moles of NaCl are dissolved in 4kg of water? How many moles of solute are present in 2 kg of a 3 m solution? How many moles of solute are present in 2 kg of a 3 m solution? What mass of alcohol do you need to add to 4 moles of benzene to make a 2 m solution? What mass of alcohol do you need to add to 4 moles of benzene to make a 2 m solution? What is the molality of a solution created by dissolving 3.50 moles methanol in 340g of CCl 4. What is the molality of a solution created by dissolving 3.50 moles methanol in 340g of CCl 4. What mass of ethanol (C 2 H 5 OH) is required to add to 4.5 kg of water to create a.86 m solution? What mass of ethanol (C 2 H 5 OH) is required to add to 4.5 kg of water to create a.86 m solution?.5 m “molal” 6 moles 2 kilograms 10.3 m 180 g C 2 H 5 OH

16. Back Bires, 2010 Slide 16 Solution Preparation By solid dissolving: By solid dissolving: 1. calculate how many grams are needed to create our volume of our desired molarity solution 1. calculate how many grams are needed to create our volume of our desired molarity solution 2. weigh out that mass, and add it to a flask 2. weigh out that mass, and add it to a flask 3. add some water and allow to dissolve 3. add some water and allow to dissolve 4. add water to the desired volume 4. add water to the desired volume By dilution of a standard solution: By dilution of a standard solution: 1. use the relationship M 1 V 1 =M 2 V 2 1. use the relationship M 1 V 1 =M 2 V 2 2. calculate volume of standard molarity solution to use to get desired volume of desired molarity solution. 2. calculate volume of standard molarity solution to use to get desired volume of desired molarity solution. End of chapter 13…C14 (quant sol) next

17. Back Bires, 2010 Slide 17 Begin C14: Colligative Properties “Colligative” means depends on amount. “Colligative” means depends on amount. –property of a solution depends on the amount of solute dissolved in solution. Physical Properties of a solution change because solute particles act as impurities, getting in the way of solvent particles. Physical Properties of a solution change because solute particles act as impurities, getting in the way of solvent particles. –lowers freezing points –increases boiling points –reduces vapor pressure. Ethyl glycol is added to water in your car’s radiator to increase water’s boiling point. The more impurities, the greater the change

18. Back Bires, 2010 Slide 18Osmosis travel of a solvent travel of a solvent –from an area of low concentration to high concentration –From high purity to low purity. Examples of osmosis: Examples of osmosis: –A Cucumber placed in a conc. NaCl solution (brine) loses water, shrivels up, and becomes a pickle. –Limp carrots and celery, placed in water, become firm because water enters via osmosis. From pure to impure 

19. Back Bires, 2010 Slide 19 Will it dissolve? (Solubility Rules) Not all ionic solids (salts) will dissolve. Not all ionic solids (salts) will dissolve. We use solubility rules to decide if the substance will dissolve. We use solubility rules to decide if the substance will dissolve. Salts containing… Salts containing… 1. Alkali metal cations(+) are soluble. 2. NH 4 +, NO 3 -, ClO 3 -, SO 4 2- are soluble. 3. Pb +, Ag +, Hg 2+ are insoluble. 4. CO 3 -, PO 4 3-, S 2- are insoluble. Which of the following salts are soluble? Which of the following salts are soluble? NaCl, HgCO 3, Ca(NO 3 ) 2, AgF, PbI 2, FeSO 4 NaCl, HgCO 3, Ca(NO 3 ) 2, AgF, PbI 2, FeSO 4 BaSO4, SrSO4, and PbSO4 are insoluble HUGE ON THE AP TEST!

20. Back Bires, 2010 Slide 20 Dissociation and Ions Present Dissociation = a salt dissolving into its ions: Dissociation = a salt dissolving into its ions: How many moles of ions are in a solution of 1 mole of NaCl? How many moles of ions are in a solution of 1 mole of NaCl? How many moles of ions are in solutions of 1 mole of each of the following?: How many moles of ions are in solutions of 1 mole of each of the following?:

21. Back Bires, 2010 Slide 21 Net Ionic Equations When we write a balanced chemical equation, we show all species present (all reactants and all products): When we write a balanced chemical equation, we show all species present (all reactants and all products): In a net ionic equation, we show only precipitates formed, and the reactants that form them: In a net ionic equation, we show only precipitates formed, and the reactants that form them: The chemicals that stay ions are called spectator ions, And are left out (Na +, NO 3 - ) The chemicals that stay ions are called spectator ions, And are left out (Na +, NO 3 - ) Remember to Balance HUGE ON THE AP TEST!

22. Back Bires, 2010 Slide 22 Net Ionic Equation Practice Write the net ionic equations for the following: Write the net ionic equations for the following:

23. Back Bires, 2010 Slide 23 Strong/Weak Electrolytes Review Recall that a solid compound made up of a cation and anion is called a salt. Recall that a solid compound made up of a cation and anion is called a salt. Salts that dissolve completely into their ions when put in water dissociate completely. Salts that dissolve completely into their ions when put in water dissociate completely. Salts that dissociate completely form strong electrolytes – solutions that conduct electricity well. Salts that dissociate completely form strong electrolytes – solutions that conduct electricity well. Some salts only partially dissociate, forming weak electrolytes – solutions that conduct electricity, but do so poorly. Some salts only partially dissociate, forming weak electrolytes – solutions that conduct electricity, but do so poorly.

24. Back Bires, 2010 Slide 24 H + / OH - Ions – (Acids and Bases) When a H + ion is released into solution, a H 3 O + ion is produced, called Hydronium ion. When a H + ion is released into solution, a H 3 O + ion is produced, called Hydronium ion. When a OH- ion is produced, we call this a Hydroxide ion. When a OH- ion is produced, we call this a Hydroxide ion. Acids that dissociate completely, releasing H+ ions form strong electrolytes. Acids that dissociate completely, releasing H+ ions form strong electrolytes. Bases that dissociate completely releasing OH- ions form strong electrolytes. Bases that dissociate completely releasing OH- ions form strong electrolytes. End of chapter 13,(14) – Problem set on next slide

25. Back Bires, 2010 Slide 25 Chapter 14 Quiz Review Problems In your text, on page 447, do the following (for a grade) as a quiz review: In your text, on page 447, do the following (for a grade) as a quiz review: #1-2 : Solubility of salts #1-2 : Solubility of salts #13-15 : Dissociation of aqueous salts #13-15 : Dissociation of aqueous salts #16-18 : Precipitation reactions, net ionic equations, and spectator ions #16-18 : Precipitation reactions, net ionic equations, and spectator ions

26. Back Bires, 2010 Slide 26 CCSD Syllabus Objectives 14.1: Solutions, Suspensions, Colloids 14.1: Solutions, Suspensions, Colloids 14.2: Solvents-polarity, like dissolves like 14.2: Solvents-polarity, like dissolves like 14.3: Molarity Calculations 14.3: Molarity Calculations 14.4: Solubility Graphs 14.4: Solubility Graphs 14.5: Molality Calculations 14.5: Molality Calculations 14.6: Colligative Properties 14.6: Colligative Properties 14.7: Freezing Point Depression 14.7: Freezing Point Depression 14.8: Boiling Point Elevation 14.8: Boiling Point Elevation 15.1: Acids and Bases 15.1: Acids and Bases 15.2: Acidic and Basic Compounds 15.2: Acidic and Basic Compounds 15.8: Strong and Weak Acids and Bases 15.8: Strong and Weak Acids and Bases

27. Back Bires, 2010 Slide 27 Aligned Labs and Demos Soda Pop: Henry’s Law Soda Pop: Henry’s Law Tyndall Laser Demo: Mixture Types Tyndall Laser Demo: Mixture Types Veggie Demo (cucumber/celery): Osmosis Veggie Demo (cucumber/celery): Osmosis Electrolyte Lab: Electrolytes Electrolyte Lab: Electrolytes Ethylene Glycol/Saltwater MiniLab: Colligative Properties Ethylene Glycol/Saltwater MiniLab: Colligative Properties Au Penny Lab: Solution Preparation, Alloys, Molarity Calculation Au Penny Lab: Solution Preparation, Alloys, Molarity Calculation