1. Chapter 12
Solutions

2. Part 1: What Is a Solution?
Homogenous mixture of two or more substances
Solvent—material present in largest amount
Solute—material to be dissolved
Consider sugar dissolved in water.
Water is the solvent.
Sugar is the solute.

3. 12.1 What Is a Solution? (Continued)
Types of solutions
Liquid/solid
Sugar dissolved in water
Liquid/liquid
Vinegar, which is acetic acid in water
Solid solution (solid/solid)
Metal alloy

4. 12.1 What Is a Solution? (Continued)
Aqueous solutions
Where water is the solvent
Most common type of solution
Aqua is Latin for water.

5. 12.2 Formation of Solutions
Why is water considered the universal solvent?
Bend shape of the molecule
Partial charges on either “end” of molecule
Able to stick to many different particles
Water is a POLAR molecule

6. 12.2 Formation of Solutions
Solute-separation: Dissociation!
Freeing of ions from the crystal lattice of the solute…
Also happens with
molecular
compounds
but the molecules
stay intact
Dissociation Animation

7. 12.4 Solubility, Temperature, and Pressure
Amount of solute that can be dissolved per amount of solvent
Affected by:
Temperature
Nature of the solute and solvent (polar or nonpolar)
Pressure (only for gas solubility)

8. 12.4 Solubility, Temperature, and Pressure
Temperature Effects for Solid Solutes

9. 12.4 Solubility, Temperature, and Pressure
Solubility Relationships

10. 12.4 Solubility, Temperature, and Pressure
Pressure Effects on Gases

11. 12.4 Solubility, Temperature, and Pressure
Saturated solution
When the maximum amount of solute is dissolved in the solvent
Any point on a solubility graph represents a saturated solution
Ex: At 20oC, 20g of CuSO4 dissolved in 100g of water makes a saturated solution
How much copper sulfate is required to make 200g of saturated solution at the same temperature?

12. 12.4 Solubility, Temperature, and Pressure
Identity of Solute

13. 12.4 Solubility, Temperature, and Pressure
Unsaturated solution
When less than the maximum amount of solute is dissolved in the solvent
Any point below a solubility graph represents a saturated solution
Ex: At 20oC, 10g of CuSO4 dissolved in 100g of water makes an unsaturated solution
Would 40g NaCl make an unsaturated solution at 50oC?

14. 12.4 Solubility, Temperature, and Pressure
Identity of Solute

15. 12.4 Solubility, Temperature, and Pressure
Supersaturated solution
When more than the maximum amount of solute is dissolved in the solvent
Any point above a solubility graph represents a saturated solution
Ex: At 20oC, 30g of CuSO4 dissolved in 100g of water makes a supersaturated solution
What mass of LiCl is required to make a supersaturated solution at 70oC?

16. 12.5 Dissolving “Unlikes” with Detergents
Water dissolves polar substances very well.
What about nonpolar substances?
Can use a nonpolar liquid (like CCl4)
Dangerous and expensive
This is done at the dry cleaner
Use a soap or detergent
Soap molecule is both polar and nonpolar
Nonpolar end dissolves nonpolar stuff
Polar end dissolves in water

17. 12.5 Getting Unlikes to Dissolve

18. Part 2

19. 12.6 Concentration Concentration
Amount of solute per amount of solvent or per amount of solution
Qualitative terms
Weak versus strong
Dilute versus concentrated
Quantitative terms
Molarity
Percent composition

20. 12.6 Molarity Molarity Number of moles of solute per liter of solution
Example: NaCl = g/mol
Dissolving g NaCl in 1L water =1M solution

21. Preparing a solution by dilution
Use the dilution equation to find the amount of stock solution needed.
Dilute to the desired amount of solution.
Dilution Equation
( Mstock solution)(Vstock solution) = (Mdiluted solution )(Vdiluted solution )

22. 12.6 Dilution
What volume of 0.50 M NaCl stock solution is needed to form 500 mL of 0.15 M NaCl solution?

23. Dilution
Remember dilution changes volume, not the number of moles present.

24. 12.7 Percent Composition Percent composition
Amount of solute divided by amount of solution
Three main types of percent composition:
Percent composition by mass (mass %)
Percent composition by volume (vol %)
Percent composition by mass/volume (% m/v)

25. 12.7 Percent Composition (Continued)
What is the percent-by-mass concentration of a solution containing 10.0 g of sucrose and enough water to make 100 g of solution in total?

26. 12.7 Percent Composition (Continued)
What is the percent-by-mass concentration of a
solution containing 10.0 g of sucrose and enough
water to make 100 g of solution in total?

27. 12.7 Percent Composition (Continued)
What is the percent-by-volume concentration of a solution made from 25.0 mL of liquid ethanol and enough water to give mL of solution?

28. 12.7 Percent Composition (Continued)
What is the percent-by-volume concentration of a
solution made from 25.0 mL of liquid ethanol and
enough water to give mL of solution?

29. Part 3

30. 12.9 Colligative Properties of Solutions
Normal boiling point
Temperature where a liquid boils at one atmosphere
Normal freezing point
Temperature where a liquid freezes at one atmosphere

31. 12.9 Colligative Properties of Solutions
Heating Curve of Water

32. 12.9 Colligative Properties of Solutions (Continued)
Colligative property
Property that depends on the number of solute particles
Does not depend on type of particle, only number of particles
Melting point and freezing point are examples because they both change when a solute is dissolved in water. Let’s see…

33. 12.9 Colligative Properties of Solutions
Colligative property (continued)

34. 12.9 Colligative Properties of Solutions (Continued)
How many moles of dissolved solute particles are
present in each of the following beakers?

35. 12.9 Colligative Properties of Solutions (Continued)
How many moles of dissolved solute particles are
present in each of the following beakers?
The two solutions contain equal numbers of
dissolved solute particles. Remember that the
NaCl dissociates to Na+ and Cl-.

36. 12.9 Colligative Properties of Solutions (Continued)
Since colligative properties depend only on the number of particles in solution…
Both solutions would have the same change in boiling point and freezing point! (1MNaCl (aq) and 2M(aq))

37. Complete lab report(s)!
End of Chapter 12
Exam 3 = chapters 8,9 and 12
Studying…
Pick up an objective sheet
Make sure you know how to write formulas! REALLY!
Do text problems that go along with the notes
Complete lab report(s)!
Final EXAM! Use notes, old exams and text problems!

38. Molarity can be used in conversions!
Ex: How many moles of NaCl are there in 500 mL of1.0 M NaCl solution? How many grams?

39. 12.6 Molarity
Ex: How many moles of NaCl are there in 500 mL of1.0 M NaCl solution? How many grams?
500mLx 1L/1000mL = 0.5L
M= moles solute/Liters solution
1.0M = x moles/0.5L
X= 0.5moles NaCl

40. 12.6 Molarity
Ex: How many moles of NaCl are there in 500 mL of1.0 M NaCl solution? How many grams?
NaCl= g/mol
0.5moles NaCl x g/mol= g

41. 12.6 Molarity (Continued)
How many moles of NaCl are there in 200 mL of 1.0 M NaCl solution? How many grams?

42. 12.6 Molarity (Continued) How many mL of a 1.500 M solution of NaCl do
you need to obtain g of NaCl?
NaCl= g/mol
100.g NaCl / g/mol x =1.71moles NaC
1.500M= 1.71mols/ X Liters
X= 1.14L
1.14lL x 1000ml/L= 1140mL of solution

43. 12.6 Molarity (Continued)
Preparing a solution from scratch
Calculate the amount of material that is needed.
Add material to the flask and dilute to the known volume.

44. How would you prepare 500.0 mL of a 0.15 M NaCl solution?
12.6 Molarity (Continued)
How would you prepare mL of a 0.15 M NaCl solution?

45. 12.6 Molarity (Continued) How would you prepare 500.0 mL of a 0.15 M
NaCl solution?
Then add enough water to form the 500 mL of
solution.

46. 12.6 Molarity (Continued)
What volume of 0.50 M NaCl stock solution is needed to form 500 mL of 0.15 M NaCl solution?

47. 12 Cool Lab Type Solution Problem
How many moles of CaF2 are there in 25.0 mL of
0.350 M CaF2(aq)?

48. 12 Cool Lab Type Solution Problem
How many moles of CaF2 are there in 25.0 mL of
0.350 M CaF2(aq)?

49. 12 Cool Lab Type Solution Problem
What volume of M CaF2 solution contains mole of CaF2?

50. 12 Cool Lab Type Solution Problem
What volume of M CaF2 solution is required
to obtain mole of CaF2?

51. 12 Cool Lab Type Solution Problem
How would you prepare 9.70 g of PbCl2(s) from a
0.100 M solution of Pb(NO3)2 and a M
solution of CaCl2?

52. 12 Cool Lab Type Solution Problem
How would you prepare 9.70 g of PbCl2(s) from a
0.100 M solution of Pb(NO3)2 and a M
solution of CaCl2?
Step 1: Write the balanced chemical equation:
Pb(NO3)2(aq) + CaCl2(aq) 
PbCl2(s) + Ca(NO3)2(aq)

53. 12 Cool Lab Type Solution Problem
How would you prepare 9.70 g of PbCl2(s) from a
0.100 M solution of Pb(NO3)2 and a M
solution of CaCl2?
Step 2: Convert given product mass to moles:

54. 12 Cool Lab Type Solution Problem
How would you prepare 9.70 g of PbCl2(s) from a
0.100 M solution of Pb(NO3)2 and a M
solution of CaCl2?
Step 3: Use molar ratio to determine moles of reactants required

55. How would you prepare 9. 70 g of PbCl2(s) from a 0
How would you prepare 9.70 g of PbCl2(s) from a M solution of Pb(NO3)2 and a M solution of CaCl2?
Step 4: Convert from moles to desired units:

56. 12.8 Reactions in Solution (Continued)
How would you prepare 9.70 g of PbCl2(s) from a
0.100 M solution of Pb(NO3)2 and a M
solution of CaCl2?
So you would combine 349 mL of the lead nitrate
solution with 175 mL of the calcium chloride
solution, and then use a funnel and filter paper to
isolate the 9.70 g of PbCl2 that forms.

57. 12.9 Colligative Properties of Solutions (Continued)
Calculating changes in freezing point and boiling point:
Kf = freezing-point constant
Kb = boiling-point constant

58. 12.2 Energy and the Formation of Solutions (Continued)
Hydrogen bonding
Leads to strong attractions called hydrogen bonds

59. 12.2 Formation of Solutions
Dissolution of an ionic salt
Water allows for:
Solute-separation—freeing of ions from the crystal lattice of the solute
Solvent-separation—breaking apart of the water molecules
Solvation—moving of the ions into spaces in the solvent
All occurs at once as the salt dissolves.

60. 12.2 Energy and the Formation of Solutions (Continued)
Solvent-separation step
Making room in the solvent for the ions

61. 12.2 Energy and the Formation of Solutions (Continued)
Solvation step
Formation of attractive forces between solvent particles and the solute particles

62. 12.2 Energy and the Formation of Solutions (Continued)
Hydration
The surrounding of solute ions by solvent molecules
Solvation when water is the solvent

63. 12.2 Energy and the Formation of Solutions
A solute dissolves when:
the energy released during solvation is larger than the energy needed in the first two steps

64. 12.2 Energy and the Formation of Solutions (Continued)
Consider the ionic compound magnesium chloride,
MgCl2. Do you think the hydration energy for this
compound is greater than, less than, or about
equal to that of NaCl?

65. 12.2 Energy and the Formation of Solutions (Continued)
Consider the ionic compound magnesium chloride,
MgCl2. Do you think the hydration energy for this
compound is greater than, less than, or about
equal to that of NaCl?
Since in MgCl2 the Mg has a +2 charge where Na
has a +1 charge, the hydration energy released
for MgCl2 would be larger.

66. 12.2 Energy and the Formation of Solutions (Continued)
System
Combination of solute and solvent
Examining energy changes will decide if a solute dissolves
E is symbol for energy changes
If overall E is positive, the solute will not dissolve.
If overall E is negative, the solute will dissolve.

67. 12.2 Energy and the Formation of Solutions (Continued)
For a given solute in water, the energy changes
are Esolute separation = 835 kJ, Esolvent separation = 98 kJ,
and Esolvation = 805 kJ. Will this solute dissolve in
water? Explain your answer.

68. 12.2 Energy and the Formation of Solutions (Continued)
For a given solute in water, the energy changes
are Esolute separation = 835 kJ, Esolvent separation = 98 kJ,
and Esolvation = 805 kJ. Will this solute dissolve in
water? Explain your answer.
Esolute separation + Esolvent separation = 933 kJ
More energy is needed (933 kJ) than released
(805 kJ), so the solute will likely not dissolve.

69. 12.5 Getting Unlikes to Dissolve—Soaps and Detergents (Continued)
Micelle
Structure soap/detergent molecules form in water
Minimize polar/nonpolar interactions between solvent and solute
Nonpolar molecules dissolve into the center of the micelle.

70. 12.6 Molarity (Continued) How many mL of a 1.500 M solution of NaCl do
you need to obtain g of NaCl?

71. When ions come in contact with one another in a solution
12.8 Reactions in Solution
When ions come in contact with one another in a solution
Diffusion—random ion movement about in solutions
Solvent cage—ion surrounded by water molecules

72. 12.8 Reactions in Solution (Continued)
Stoichiometry
Molarity is key for converting to and from moles.
Once you know moles, you can understand stoichiometry.

73. 12.8 Reactions in Solution (Continued)

74. 12.9 Colligative Properties of Solutions (Continued)
Dynamic equilibrium
When the rate of a forward reaction is equal to the reverse process

75. 12.9 Colligative Properties of Solutions (Continued)
Vapor pressure
Pressure exerted by the gas molecules of a liquid