1. 4B Chapter 13 Notes

2. Stephanie Hutchinson Tre Jennings
Dissociation
Stephanie Hutchinson
Tre Jennings

3. Dissociation
Dissociation: The separation of ions that occurs when an ionic compound dissolves.
Chemical equations in dissociation require balanced charge as well as atoms.
For now, 100% dissociation can always be assumed.

4. Example The dissociation of NaCl can be represented as follows:
NaCl(s)Na+(aq)+Cl-(aq)
The dissociation of Al2(SO4)3 can b e represented as follows:
Al2(SO4)3(s)2Al3+(aq)+3SO42-(aq)

5. Net Ionic Equation

6. What is a net ionic equation?
A net ionic equation includes only those compounds and ions that undergo a chemical change in a reaction in an aqueous solution.

7. Writing a net equation
First convert the chemical equation into an overall ionic equation.
All soluble ionic compounds are shown as dissociated ions in solution.
The precipitates are shown as solids.
Ions that do not take part in a chemical reaction and are found in solution both before and after the reaction are spectator ions.

8. Complete Ionic Equation
General Equation
Cd(NO3)2(aq) + (NH4)2S(aq) 
CdS(s) + 2NH4NO3(aq)
Complete Ionic Equation
Cd2+(aq) + 2NO3-(aq) + 2NH4+(aq) + S2-(aq)  CdS(s) + 2NO3-(aq) + 2NH4+(aq)
Net Ionic Equation
Cd2+(aq) + S2-(aq)  CdS(s)

9. Electrolytes
By: Pariis Yi, Chase Young, Joey Wofford, Parker Meek, Jonathan Binkley

10. Electrolytes: A general overview
Electrolyte: substance that dissolves in water to give a solution that conducts an electric current
A mole of an electrolyte dissolves to make two moles in the solution
Non-electrolyte: the substance that does not yield ions and does not conduct an electric current in solution

11. Colligative Properties
Electrolyte is an ionic compound
Non-ionic compounds cannot form electrolytes
Depends on number of parts

12. Strong Electrolytes
Strong Electrolyte: any compound whose dilute aqueous solutions conduct electricity well
There is a presence of all or almost all of the dissolved compound in the form of ions
There is a higher concentration of ions

13. Example
NaCl(s) = Na+(aq) + Cl-(aq)

14. Weak Electrolytes
Weak Electrolytes: any compound whose dilute aqueous solutions conduct electricity poorly
There is a presence of a smaller amount of the dissolved compound in the form of ions
There is a lower concentration of ions

15. Example
H2CO3(aq) = H+(aq) + HCO3-(aq)

16. Freezing Point Depression
Abby Brazinski & Natasha Zelenka

17. The molal freezing point constant for water is -1.86°C/m.
The freezing point of a 1m solution of any nonelectrolyte solute in water is 1.86°C lower than the freezing point of water.
The molal freezing point constant for water is -1.86°C/m.
The molal freezing point constant is the freezing-point depression of the solvent in a 1-molal solution of a nonvolatile nonelectrolyte solution.
Each solvent has its own freezing point constant.

18. Freezing Point Depression
Freezing-point depression, Δtf , is the difference between the freezing points of the pure solvent and a solution of a nonelectrolyte in that solvent, and it is directly proportional to the molal concentration of the solution.

19. Equation Equation: Δtf = Kfm Kf is expressed as °C/m
m is mol solute/kg solvent (molality)
Δtf is expressed as the freezing-point depression and is expressed in °C
See page 449 in the textbook for an example.

20. Allison Johnson David Holland, Jr.
Osmic Pressure
Allison Johnson
David Holland, Jr.

21. Definitions:
Osmic Pressure is the external pressure that must be applied to stop osmosis
Osmosis – movement of a solvent through a semi permeable membrane* from the side of higher concentration to lower concentration
*Semi permeable membrane – allows some particles to pass through while preventing others.

22. Other facts:
Is dependent on concentration of particles, not the type of particles in the solutions
Greater the concentration of a solution, the greater the osmic pressure

23. Example:
On one side of the semi permeable membrane is a solution (salt water) and on the other would be the pure solvent (water). Because of the presence of the NaCl molecules in the solution, the solvent is blocked and fewer water molecules are able to reach the membrane and pass through than on the side with pure water…

24. Example:
The pure water passes through the membrane faster and raises the volume of the solution until the pressure exerted by the height of the solution is enough to force the water molecules in the solution back through the membrane at the same rate the water passes through on the other side.

25. Vapor Pressure Lowering
Kaitlynn Motley
Artaza Khan
Ishaan Sandhu

26. Vapor Pressure
-- The pressure caused by molecules in the gas phase that are in equilibrium with the liquid phase

27. Colligative Properties
-- Properties that depend on the concentration of solute particles but not on their identity
Unit: molality (m)

28. Nonvolatile Substances
-- Substance that has little tendency to become a gas under existing conditions
Raises boiling point
Lowers freezing point
When solute in solution, has lower vapor pressure than vapor pressure of pure solvent
Vapor pressure of solution = less than pure water

29. Properties
Nonelectrolyte solutions w/ same molality have same particle concentration
Equally dilute molal solutions of any type of nonelectrolyte solvent in any solution lower vapor pressure equally
Lowering depends on concentration of nonelectrolyte solute
Independent of solute identity
Colligative property

30. example
Vapor pressure of water over pure water greater than vapor pressure of water over an aqueous solution containing a nonvolatile solute

31. Boiling-Point Elevation
Taylor Walsh
Justin Corr
Brendan Korando

32. The cool slide
A change in vapor pressure of a liquid will cause a change in the boiling point.
The boiling point of a solution is higher then boiling point of a solvent.

33. Molal Boiling-Point ConstantKb
The boiling point elevation of a solvent in a 1-Molal solution of a nonvolatile, nonelectrolyte solute.
The Molal Boiling point constant for water is .51 degrees Celsius/m

34. Boiling Point Elevation
The difference between the boiling points of the pure solvent and a nonelectrolyte solution of that solvent, and it is directly proportional to the molal concentration of the solution.
Δtb = Kbm
Kb = degrees Celsius/m
Δtb = The boiling Point Elevation

35. EXAMPLE