1. Objectives/Goals for Today
Exam 4 on Chapters 10 & 11
Chapter 13 notes
Section 13.1
Section 13.2
Section 13.3
Section 13.4
Section 13.5
Section 13.6

2. Chapter Thirteen Physical Properties of Solutions

3. Section 13.1 Types of Solutions

4. Types of Solutions Recall: A solution is a homogeneous mixture
Made up of a solvent & one or more solutes

5. Solubility
The amount of solute that can be dissolved in a given solvent at a specific temperature
Unsaturated: less than the max amount
Saturated: the max amount
Supersaturated: more than the max amount

6. Section 13.2 A Molecular View of the Solution Process

7. Solvation
The process of solvent molecules breaking apart solute particles
Solvation Process
Solvation depends on 3 types of interactions
Solute-Solute interactions
Solvent-Solvent interactions
Solute-Solvent interactions

8. Types of Interactions
Recall: In Chapter 12 we talked about intermolecular forces that existed between molecules, atoms, or ions of a pure substance
London Dispersion
Dipole-Dipole
Ion-Ion forces
Because mixtures have different properties w/in, there are more forces that can be present

9. Intermolecular Forces in Solutions

10. Enthalpy of Solution
When solute and solvent mix to make solutions, it has an associated enthalpy change known as ΔHsoln.
ΔHsoln = ΔH1 + ΔH2 + ΔH3
When ΔHsoln > Endothermic
When ΔHsoln < 0 Exothermic

11. Check For Understanding
Which of the following compounds do you expect to be more soluble in benzene than in water?
SO2, CO2, Na2SO4, C2H6, Br2

12. Section 13.3 Concentration Units

13. Concentrations
Recall: concentration shows how much solute is in a solution or solvent
Molarity: (M) moles of solute/L of solution
Mole Fraction: (X) moles of solute/moles of solution
Two additional concentrations:
Molality (m)
Percent by Mass

14. Concentrations Molality Percent by Mass Moles of solute/kg of solvent
(Mass of solute/mass of solution) x 100
Percent means “parts per hundred”
If we multiplied by 1000, it would be “parts per thousand”
1,000,000 (parts per million, ppm)
1,000,000,000 (parts per billion, ppb)

15. Practice
Determine the percent by mass of KCl in a solution prepared by dissolving 1.18 g of KCl in 86.3 g of water.
What is the molality of a solution prepared by dissolving 6.44 g of naphthalene (C10H8) in 80.1 g of benzene?

16. Section 13.4 Factors that Affect Solubility

17. Factors Affecting Solubility
Two factors affect the solubility of solutes in solutions:
Temperature
Pressure
As temperature rises, most solids solubility increases
As temperature rises, gases solubility decreases

18. Factors Affecting Solubility
Pressure doesn’t affect solids or liquids much
Gases are affected much more by pressure
Henry’s Law
The solubility of a gas in a liquid is proportional to the pressure of the gas

19. Section 13.5 Colligative Properties

20. Colligative Properties
Properties that depend ONLY on the number of solute particles in solution
Vapor-Pressure Lowering
Boiling-Point Elevation
Freezing-Point Depression
Osmotic Pressure

21. Vapor-Pressure Lowering
Vapor pressure is the pressure of the vapor above a liquid (or solid) at equilibrium
When a solute is added to a solvent, the vapor pressure of the solvent (above the resulting liquid) is LOWER than that of the pure solvent.

22. Vapor-Pressure Lowering

23. Vapor-Pressure Lowering
Raoult’s Law

24. Boiling-Point Elevation
Boiling Point: temperature at which a pure substance will vaporize (or boil)
Where vapor pressure = atmospheric pressure
Because adding solute lowers vapor pressure, more temperature is necessary to get vapor pressure to equal atmospheric pressure
Boiling Point Elevates

25. Freezing-Point Depression
Freezing Point: the temperature at which a substance freezes
The presence of a solute with a solvent lowers (or depresses) the temperature
More energy has to be removed in a solution than in a pure substance

26. Boiling Point & Freezing Point

27. Osmosis & Osmotic Pressure
Osmosis is the movement of solvent particles (through a semipermeable membrane) from a more dilute solution to a more concentrated solution
Osmotic pressure:
Pressure required by
a solution to stop
osmosis

28. Section 13.6 Calculations Using Colligative Properties

29. Boiling-Point Elevation
To calculate how the boiling point is elevated:
ΔTb = Kbm
where ΔTb is the boiling point elevation
Kb is molal boiling-point elevation constant
m is the molality of the solution

30. Freezing-Point Depression
To calculate how the freezing point is depressed:
ΔTf = Kfm
where ΔTf is the freezing point depression
Kf is molal freezing-point depression constant
m is the molality of the solution

31. Practice
Determine the boiling point and the freezing point of a solution prepared by dissolving 678 g of glucose in 2.0 kg of water. For water, Kb = 0.52°C/m and Kf = 1.86 °C/m
Calculate the freezing point and boiling point of a solution containing 268 g of ethylene glycol (C2H6O2) in 1015 g of water.