1. Mr. Kinton Honors Chemistry
IMF’s and Solutions
Mr. Kinton Honors Chemistry

2. Recall What do you remember about solids and their structure?
What about liquids and their structure?
Intra-particle forces: Ionic, Covalent, and Metallic bonds
Classification of Matter:

3. Intermolecular Forces
The forces that exist between molecules
Weaker than Intra-particle forces
Determine the properties of liquids such as boiling point
Low boiling point=weaker IMF’s
High boiling point=stronger IMF’s
Same holds true for solids and their melting point

4. Types of Intermolecular Forces
There are 3 types of intermolecular forces in neutral molecules:
London-Dispersion forces
Dipole-dipole forces
Hydrogen Bonding
The 3 are referred to as the van der Waals forces
Each are electrostatic in nature

5. London Dispersion Forces
Caused by electrons repelling one another
Creates a temporary dipole
Strongest in larger molecules
Polarizability: the ability of an atoms electric field to be distorted
Exist in all molecules

6. Dipole-Dipole Forces
Positive end of one molecule is near the negative end of another molecule
Only effective when polar molecules are near each other
Dipole-Dipole forces occur between only polar molecules

7. Hydrogen Bonding
Special type of attraction between a Hydrogen atom and either a F, O, or N atom of an adjacent molecule
Causes higher than usual melting/boiling points
Strongest intermolecular force

8. Ion-Dipole Force Attraction between an ion and a polar molecule
Increases based on charge of the ion or the dipole moment
Important in the formation of solutions

9. Melting/Boiling Points

10. IMF Flow Chart

11. Solution V. Colloid v. Suspension

12. Solutions Are they substances or mixtures?
IMF’s interact between the solute and the solvent
Solute: substance being dissolved
Solvent: substance doing the dissolving

13. How do Solutions form
Attractive forces between solute and solvent are comparable to the individual forces
Solvation: when ions are separated and surrounded by a solvent
Hydrations: solvation when water is the solvent
This is a physical change

14. Energy Of Solution Formation

15. Energy Changes Exothermic Endothermic
heat is released to the surroundings
Spontaneous
Feels warm
heat is absorbed from the surroundings
Can be spontaneous
Feels cold

16. Entropy The amount of disorder in a system
Processes that increase entropy tend to occur spontaneously
Solution formation is favored when entropy increases

17. Solutions and Solubility
Solubility: amount of solute needed to form a saturated solution in a solvent
Saturated: solution that is in equilibrium with undissolved solute
Unsaturated: less solute is dissolved than possible in a solution
Supersaturated: occurs when a solution is heated, more solute is added, then cooled

18. Solubility Curves

19. Factors Affecting Solubility
Solute-Solvent Interactions
Pressure Effects
Temperature Effects

20. Solute-Solvent Interactions
Increase when there are stronger attractions between solute and solvent
Hence “like dissolves like”
Miscible: liquids that mix in all proportions
Immiscible: liquids that do not dissolve each other

21. Pressure Effects Only impacts gases in solution
Increasing pressure causes an increase in gas concentration

22. Temperature Effects
Increase in temperature causes an increase in solid solubility
Increase in temperature causes a decrease in gas solubility

23. Ways of Expressing Concentration
Qualitatively
quantitatively
Dilute: relatively small concentration
Concentrated: large concentration of solute
Mass percentage
Mole fraction
Molarity
Molality

24. Colligative Properties
Properties that depend on the concentration of solute particles
As the number of solute particles increase so do the colligative properties as well
4 Colligative Properties
Vapor Pressure
Boiling-Point Elevation
Freezing-Point Depression
Osmosis

25. Vapor Pressure Pressure exerted by a vapor in a closed container
Nonvolatile: no measurable vapor pressure
Volatile: has a measurable vapor pressure
Adding a nonvolatile will lower the vapor pressure

26. Boiling Point Elevation/Freezing Point Depression
Based on the presence of nonvolatile in the solution
Adding a nonvolatile increases the boiling point, but lowers the freezing point
Adding an electrolyte increases the effect

27. Osmosis
Net movement of solvent toward a solution with higher concentration
Stops when the osmotic pressure can stop the movement of the solvent