1. Chapter 12 Solutions Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

2. Chapter 12 Slide 2 of 41 Solute and Solvent Solutions Are homogeneous mixtures of two or more substances. Consist of a solvent and one or more solutes. Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

3. Chapter 12 Slide 3 of 41 Solutes Spread evenly throughout the solution. Cannot be separated by filtration. Can be separated by evaporation. Are not visible, but can give a color to the solution. Nature of Solutes in Solutions Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

4. Chapter 12 Slide 4 of 41 Examples of Solutions The solute and solvent can be a solid, liquid, and/or a gas. Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

5. Chapter 12 Slide 5 of 41 Identify the solute in each of the following solutions: 1. _____ sugar (A) and _________ water (B) 2. _______ of ethyl alcohol (A) and ________ of methyl alcohol (B) 3. ________ water (A) and _______ NaCl (B) 4. Air: _________ (A) and __________ N 2 (B) Learning Check

6. Chapter 12 Slide 6 of 41 Water Is the most common solvent. Is a polar molecule. Forms hydrogen bonds between the hydrogen atom in one molecule and the oxygen atom in a different water molecule. Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

7. Chapter 12 Slide 7 of 41 Formation of a Solution Na + and Cl - ions On the surface of a NaCl crystal are attracted to polar water molecules. In solution are hydrated as several H 2 O molecules surround each. Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

8. Chapter 12 Slide 8 of 41 When NaCl(s) dissolves in water, the process can be written as: H 2 O NaCl(s) Na + (aq) + Cl - (aq) solid separation of ions The Na + ions are attracted to the oxygen atom (  - ) of water. The Cl - ions are attracted to the hydrogen atom (  + ) of water. Equations for Solution Formation

9. Chapter 12 Slide 9 of 41 Two substances form a solution when there is an attraction between the particles of the solute and solvent. when a polar solvent such as water dissolves polar solutes such as sugar and ionic solutes such as NaCl. when a nonpolar solvent such as hexane (C 6 H 14 ) dissolves nonpolar solutes such as oil or grease. Like Dissolves Like

10. Chapter 12 Slide 10 of 41 Water and a Polar Solute Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

11. Chapter 12 Slide 11 of 41 Like Dissolves Like Solvents Solutes Water (polar) Ni(NO 3 ) 2 CH 2 Cl 2 (nonpolar) (polar) I 2 (nonpolar) Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

12. Chapter 12 Slide 12 of 41 Electrolytes and Nonelectrolytes Chapter 12 Solutions Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

13. Chapter 12 Slide 13 of 41 In water, Strong electrolytes produce ions and conduct an electric current. Weak electrolytes produce a few ions. Nonelectrolytes do not produce ions. Solutes and Ionic Charge Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

14. Chapter 12 Slide 14 of 41 Strong electrolytes Dissociate in water producing positive and negative ions. Conduct an electric current in water. In equations show the formation of ions in aqueous (aq) solutions. H 2 O 100% ions NaCl(s) Na + (aq) + Cl − (aq) H 2 O CaBr 2 (s) Ca 2+ (aq) + 2Br − (aq) Strong Electrolytes

15. Chapter 12 Slide 15 of 41 A weak electrolyte Dissociates only slightly in water. In water forms a solution of only a few ions and mostly undissociated molecules. HF(g) + H 2 O(l) H 3 O + (aq) + F - (aq) NH 3 (g) + H 2 O(l) NH 4 + (aq) + OH - (aq) Note: Unequal lengths of the arrows Weak Electrolytes

16. Chapter 12 Slide 16 of 41 Nonelectrolytes Dissolve as molecules in water. Do not produce ions in water. Do not conduct an electric current. Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings Sucrose

17. Chapter 12 Slide 17 of 41 Comparing Solutes in Solution

18. Chapter 12 Slide 18 of 41 Chapter 12 Solutions Solubility Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

19. Chapter 12 Slide 19 of 41 Solubility Is the maximum amount of solute that dissolves in a specific amount of solvent. Can be expressed as grams of solute in 100 grams of solvent, usually water. g of solute 100 g water Solubility

20. Chapter 12 Slide 20 of 41 Effect of Temperature on Solubility Solubility Depends on temperature. Of most solids increases as temperature increases. Of gases decreases as temperature increases. Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

21. Chapter 12 Slide 21 of 41 21 Solubility and Pressure Henry’s law states the solubility of a gas in a liquid is directly related to the pressure of that gas above the liquid at higher pressures, more gas molecules dissolve in the liquid

22. Chapter 12 Slide 22 of 41 Unsaturated Solutions Unsaturated solutions Contain less than the maximum amount of solute. Can dissolve more solute. Dissolved solute Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

23. Chapter 12 Slide 23 of 41 Saturated Solutions Saturated solutions Contain the maximum amount of solute that can dissolve. Have undissolved solute at the bottom of the container. Have equal rates at which solute dissolves and crystallizes Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings Steady State

24. Chapter 12 Slide 24 of 41 Comparing Unsaturated and Saturated Solutions More solute can dissolve in an unsaturated solution but not in a saturated solution.

25. Chapter 12 Slide 25 of 41 Soluble and Insoluble Salts Ionic compounds that dissolve in water are soluble salts do not dissolve in water are insoluble salts Double Replacement AB + CD → AD + CB

26. Chapter 12 Slide 26 of 41 Solubility Rules Soluble salts typically contain at least one ion from Groups 1A(1), NO 3 −, or C 2 H 3 O 2 − (acetate) Most other combinations are insoluble.

27. Chapter 12 Slide 27 of 41 Using the Solubility Rules The solubility rules predict if a salt is soluble in water that a solid forms if ions of an insoluble salt are present

28. Chapter 12 Slide 28 of 41 Formation of a Solid When solutions of salts are mixed, A solid forms if ions of an insoluble salt are present. Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

29. Chapter 12 Slide 29 of 41 Equations for Forming Solids A molecular equation shows the formulas of the compounds. Pb(NO 3 ) 2 (aq) + 2NaCl(aq) PbCl 2 (s) + 2NaNO 3 (aq) An ionic equation shows the ions of the compounds. Pb 2+ (aq) + 2NO 3 − (aq) + 2Na + (aq) + 2Cl − (aq) PbCl 2 (s) + 2Na + (aq) + 2NO 3 − (aq) A net ionic equation shows only the ions that form a solid. Ions remaining in solution are spectator ions. Pb 2+ (aq) + 2Cl − (aq) PbCl 2 (s)

30. Chapter 12 Slide 30 of 41 Equations for the Insoluble Salt STEP 1 Observe the ions in the reactants. Pb 2+ (aq) + 2NO 3 − (aq) 2Na + (aq) + 2Cl − (aq) STEP 2 Determine if any new ion combinations are insoluble salts. Yes. PbCl 2 (s) STEP 3 Ionic equation with insoluble salt product. Pb 2+ (aq) + 2NO 3 − (aq) + 2Na + (aq) + 2Cl − (aq) PbCl 2 (s) + 2Na + (aq) + 2NO 3 − (aq) STEP 4 Net ionic equation. Pb 2+ (aq) + 2Cl − (aq) PbCl 2 (s)

31. Chapter 12 Slide 31 of 41 Molarity and Dilution Chapter 12 Solutions Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

32. Chapter 12 Slide 32 of 41 Molarity (M) Molarity (M) is A concentration term for solutions. The moles of solute in 1 L solution. moles of solute liter of solution

33. Chapter 12 Slide 33 of 41 Preparing a 1.0 Molar Solution A 1.00 M NaCl solution is prepared By weighing out 58.5 g NaCl (1.00 mol) and Adding water to make 1.00 liter of solution. Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

34. Chapter 12 Slide 34 of 41 What is the molarity of 0.500 L NaOH solution if it contains 6.00 g NaOH? STEP 1 Given 6.00 g NaOH in 0.500 L solution Need molarity (mol/L) STEP 2 Plan g NaOH mol NaOH molarity STEP 3 Conversion factors 1 mol NaOH = 40.00 g 1 mol NaOH and 40.00 g NaOH 40.00 g NaOH 1 mol NaOH Calculation of Molarity

35. Chapter 12 Slide 35 of 41 STEP 4 Calculate molarity. 6.00 g NaOH x 1 mol NaOH = 0.150 mol 40.00 g NaOH 0.150 mol = 0.300 mol = 0.300 M NaOH 0.500 L 1 L Calculation of Molarity (cont.)

36. Chapter 12 Slide 36 of 41 Molarity Conversion Factors The units of molarity are used as conversion factors in calculations with solutions. Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

37. Chapter 12 Slide 37 of 41 Molarity in Calculations How many grams of KCl are needed to prepare 125 mL of a 0.720 M KCl solution? STEP 1 Given 125 mL (0.125 L) of 0.720 M KCl Need Grams of KCl STEP 2 Plan L KCl mol KCl g KCl

38. Chapter 12 Slide 38 of 41 Molarity in Calculations (cont.) STEP 3 Conversion factors 1 mol KCl = 74.55 g 1 mol KCl and 74.55 g KCl 74.55 g KCl 1 mol KCl 1 L KCl = 0.720 mol KCl 1 L and 0.720 mol KCl 0.720 mol KCl 1 L STEP 4 Calculate grams. 0.125 L x 0.720 mol KCl x 74.55 g KCl = 6.71 g KCl 1 L 1 mol KCl

39. Chapter 12 Slide 39 of 41 Dilution In a dilution Water is added. Volume increases. Concentration decreases. Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

40. Chapter 12 Slide 40 of 41 Comparing Initial and Diluted Solutions In the initial and diluted solution The moles of solute are the same. The concentrations and volumes are related by the equation M 1 V 1 = M 2 V 2 initial diluted

41. Chapter 12 Slide 41 of 41 Dilution Calculations What is the molarity if 0.180 L of 0.600 M KOH is diluted to a final volume of 0.540 L? STEP 1 Prepare a table: M 1 = 0.600 MV 1 = 0.180 L M 2 = ?V 2 = 0.540 L STEP 2 Solve dilution equation for unknown. M 1 V 1 = M 2 V 2 M 1 V 1 / V 2 = M 2 STEP 3 Set up and enter values: M 2 = M 1 V 1 = (0.600 M)(0.180 L) = 0.200 M V 2 0.540 L