1. CHAPTER 15 and 16
SOLUTIONS

2. Properties of Solutions
OBJECTIVES:
Identify the factors that determine the rate at which a solute dissolves.

3. Properties of Solutions
OBJECTIVES:
Identify the units usually used to express the solubility of a solute.

4. Properties of Solutions
OBJECTIVES:
Identify the factors that determine the mass of solute that will dissolve in a given mass of solvent.

5. THE NATURE OF SOLUTIONS
A solution is a homogeneous mixture of 2 or more substances in a single physical state.
Solute: A substance that is dissolved
Solvent: The substance that does the dissolving (usually a liquid)

6. How Much?
Solubility- is the maximum amount of substance that will dissolve at a specific temperature
Saturated solution- Contains the maximum amount of solute dissolved.

7. How Much? Unsaturated solution- Can still dissolve more solute
Supersaturated- solution that is holding more than it theoretically can;

8. Saturation and Equilibrium
Saturation equilibrium established
Solute is dissolving
More solute is dissolving, but some is crystallizing

9. Types of Solutions Gas-Gas Gas-Liquid Liquid-Liquid Solid-Liquid
Gas-Solid
Liquid-Solid
Solid-Solid
Air (O2 and N2)
Seltzer (CO2 and H2O)
Antifreeze
Ocean Water
Charcoal Filter
Dental Fillings
Sterling Silver

10. Types of Solutions

11. Properties of Solutions
A substance that dissolves in another substance is said to be Soluble.
Examples: Salt and Sugar
A substance that DOES NOT dissolve in another is said to be Insoluble.
Examples: Nail, rock, wood
Typically the solute is smaller / less than the solvent.

12. Solid Solutions Typically Alloys…..such as: Babbit (ball bearings)
Bell Metal (Bells)
Bronze (Coins)
18K gold (Jewelry)
Sterling Silver (Flatware)
Steel (Construction)

13. Aqueous Solutions Solutions with water as the solvent
Water can dissolve many things because of its polarity and neutrality.
Water is known as the universal solvent.

14. Liquid Solutions
Miscible: ability of a liquid to form a solution with another liquid in all proportions. (water and milk)
Immiscible: Inability of a liquid to form a solution. (oil and water)

15. Section 15.2 Concentration of Solutions
OBJECTIVES:
Solve problems involving the Molarity of a solution.

16. Section 15.2 Concentration of Solutions
OBJECTIVES:
Describe the effect of dilution on the total moles of solute in solution.

17. Concentration is...
a measure of the amount of solute dissolved in a given quantity of solvent
A concentrated solution has a large amount of solute
A dilute solution has a small amount of solute
These are qualitative descriptions
But, there are ways to express solution concentration quantitatively

18. Concentrated vs. Dilute

19. Molarity Molarity = moles of solute
liters of solution
Abbreviated with a capital M, such as 6.0 M
This is the most widely used concentration unit used in chemistry.

20. molality
molality: is a measure of the number of MOLES of solute in 1 KILOGRAM solvent.
m = mol solute / Kg solvent

21. Saturation
Saturated: A solution is saturated if it contains as much solute as can possibly be dissolved under the existing conditions of temperature and pressure.
Unsaturated: A solution that has less than the maximum amount of solute that can be dissolved is unsaturated.

22. Supersaturated: A solution that contains a greater amount of solute than that needed to form a saturated solution.

23. Exothermic and Endothermic Reactions
Exothermic Reactions
: Gives off heat (heat pack)
Endothermic Reactions
: Absorbs heat (cold pack)

24. Factors that affect solubility
1. Nature of Solute and Solvent
2. Temperature
: As temperature increases, the kinetic energy becomes greater, thus solubility increases.
3. Pressure (gases)
: As pressure increases, the kinetic energy becomes greater, thus the solubility increases.

25. Polar vs. Nonpolar Substances
Polar Molecules
: Based on molecular geometry
: If there are unshared pairs of electrons on the central atom, then POLAR (Water, CH3Cl)
Nonpolar compounds
: Symmetrical compound
: Same element on all sides
: (oil, grease, soap, Cl2, CH4)

26. Examples of polar and nonpolar substances
Water
Alcohols
Acetone
Acetic Acid
Formic Acid
NonPolar
Hexane
Octane
Carbon Tetrachloride
Greases, petroleum oils, vege. oils
Waxes, tars, gasoline

27. Like Dissolves Like Rule
Solute
Polar Solvent
Nonpolar Solvent
Polar
Soluble
Insoluble
Nonpolar
Ionic

28. Factors Affecting the Rate of Dissolving
Surface Area
: The dissolving of a solid solute takes place on the surface of the solid.
: Solvent particles pull particles from the surface of the solute into solution.
: Because dissolving occurs at the surface of the solute, it can be speeded up by increasing the surface area.
: Crushing and grinding
: Sugar cubes vs. sugar granulars vs. powdered sugar

29. Stirring
: Speeds up the dissolving process because it increases the contacts between the solute and the solvent.
Temperature
: Increasing temperature increases the speed of the molecules of the solvent.
: Faster solvent molecules means more contacts with the solute particles and thus a faster dissolving rate.

30. - Page 474

31. Solids tend to dissolve best when:
Heated
Stirred
Ground into smaller particles
Gases tend to dissolve best when:
The solution is cold
Pressure is high