1. Properties of Solutions
Chapter 18: Solutions
Properties of Solutions

2. Chapter 18: Solutions -- Properties of Solutions --
Solution Formation
Formation of homogeneous mixtures
Factors that affect solution formation (dissolving)
Nature of the solute and solvent
Amount of solute vs. solvent
Factors that affect the rate of solution formation (dissolving)
Stirring (agitation)
Temperature
Surface area
Particle size

3. Chapter 18: Solutions -- Properties of Solutions --
Solubility
How solution formation works
Only so much solute will go into solution because, once room for a solute is not present, the particles going into solution are exchanged with particles coming out of solution.
Partly responsible for precipitate formation

4. Chapter 18: Solutions -- Properties of Solutions --
Solubility
Unsaturated solution
A solution that contains less solute than a saturated solution
Most solutions are unsaturated
Solubility of a substance
The amount of a substance that dissolves in a given quantity of solvent at a given temperature to produce a saturated solution
Varies depending on temperature, kinds of solute and solvent, and other factors
Miscibility
Ability for two liquids to dissolve in each other
Example: ethanol and water
Partial miscibility
Ability for two liquids to somewhat dissolve in each other
Example: water and diethyl ether

5. Chapter 18: Solutions -- Properties of Solutions --
Solubility
Immiscibility
Inability for two liquids to dissolve in each other
Example: petroleum and water
Factors Affecting Solubility
Temperature

6. Chapter 18: Solutions -- Properties of Solutions --
Factors Affecting Solubility
Temperature (continued)
As temperature increases, generally the solubility of a solid will increase.

7. Chapter 18: Solutions -- Properties of Solutions --
Factors Affecting Solubility
Temperature (continued)
As temperature increases, generally the solubility of a gas will decrease.

8. Chapter 18: Solutions -- Properties of Solutions --
Factors Affecting Solubility
Pressure
As the gas pressure above a solution increases, the gas solubility of the solvent increases.
Gas is forced into solution more (I.e., greater solubility) if a greater gas pressure is exerted over the solution in order to keep the gas in the solution.
Henry’s Law
S1: solubility of the first solution
P1: gas pressure above the first solution
S2: solubility of the second solution
P2: gas pressure above the second solution

9. Chapter 18: Solutions -- Properties of Solutions --
Factors Affecting Solubility
Supersaturated solution
A solution that contains more than it theoretically should be able to hold at a given temperature
Results from mixing at higher temperature or pressure
(a) (b) (c)
(a): Supersaturated solution before a seed crystal is added
(b): Solution after a seed crystal has been added
(c): Excess solute in solution crystallizes rapidly

10. Concentrations of Solutions
Chapter 18: Solutions
Concentrations of Solutions

11. Chapter 18: Solutions -- Concentrations of Solutions --
Molarity
Concentration of a solution
A measure of the amount of solute that is dissolved in a given quantity of solvent
Descriptions of concentration
Qualitative measures and expressions
Dilute solutions have only low concentrations of solute
Concentrated solutions have high concentrations of solute
Expressed as “M”
Number of moles of a solute dissolved per liter of solution

12. Chapter 18: Solutions -- Concentrations of Solutions --
Molarity
Example:
Calculate the molarity of a solution made of g CuSO4 in 4.00 L of solution.
Solution:

13. Chapter 18: Solutions -- Concentrations of Solutions --
Molarity
Dilution of a solution
The total number of moles before and after solution will remain the same since no solute is being added.
Formula
M1: First solution’s molarity
M2: Second solution’s molarity
V1: First solution’s volume
V2: Second solution’s volume

14. Chapter 18: Solutions -- Concentrations of Solutions --
Molarity
Example:
You have the following stock solutions available: 2.00M NaCl, …
Calculate the volume you must dilute to make mL of 0.500M NaCl.
Solution:

15. Chapter 18: Solutions -- Concentrations of Solutions --
Percent Solutions
Percent by volume
Expressed as % (v/v)
Percent (mass/volume)
Expressed as % (m/v)

16. Chapter 18: Solutions -- Concentrations of Solutions --
Percent Solutions
Parts per million
Expressed as ppm
Used primarily for gas and living habitats
EPA usage
Other applications

17. Chapter 18: Solutions -- Concentrations of Solutions --
Percent Solutions
Example:
The Dead Sea contains 58 moles of lithium ion in 1.0 x 103 kg of seawater. Calculate the concentration, in ppm, of lithium ion in the Dead Sea.
Solution:

18. Colligative Properties of Solutions
Chapter 18: Solutions
Colligative Properties of Solutions

19. Chapter 18: Solutions -- Colligative Properties --
A property of a solution that depends only on the number of solute particles
Three colligative properties
Boiling point elevation
Vapor pressure lowering
Freezing point depression
The more solute particles in solution, the more the property occurs
More particles, the more the boiling point is elevated
More particles, the more the vapor pressure is lowered
More particles, the more the freezing point is depressed

20. Chapter 18: Solutions -- Colligative Properties --
Example
If you have equal numbers of moles of CaCl2, AlCl3, NH4NO3, and C6H12O6, which, when dissolved in solution, would have 1) the lowest freezing point, 2) the lowest vapor pressure, and 3) the lowest boiling point?
CaCl2  Ca2+ + 2Cl– (3 particles per mole)
AlCl3  Al3+ + 3Cl– (4 particles per mole)
NH4NO3  NH4+ + NO3– (2 particles per mole)
C6H12O6 (1 particle per mole; molecular, so doesn’t dissociate)

21. Chapter 18: Solutions -- Colligative Properties --
Example
If you have equal numbers of moles of CaCl2, AlCl3, NH4NO3, and C6H12O6, which, when dissolved in solution, would have 1) the lowest freezing point, 2) the lowest vapor pressure, and 3) the lowest boiling point?
Lowest (most depressed) freezing point: AlCl3
Most particles per mole (4)
Lowest (most lowered) vapor pressure: AlCl3
Lowest boiling point (opposite most elevated boiling point): C6H12O6
Least particles per mole (1)