1. Types of Chemical Reactions and Solution Stoichiometry

2. Classification of Matter
Solutions are homogeneous mixtures

3. Solute Solvent A solute is the dissolved substance in a solution.
Salt in salt water
Sugar in soda drinks
Carbon dioxide in soda drinks
Solvent
A solvent is the dissolving medium in a solution.
Water in salt water
Water in soda

4. Saturation of Solutions
A solution that contains the maximum amount of solute that may be dissolved under existing conditions is saturated.
A solution that contains less solute than a saturated solution under existing conditions is unsaturated.
A solution that contains more dissolved solute than a saturated solution under the same conditions is supersaturated.

5. Electrolytes vs. Nonelectrolytes
The ammeter measures the flow of electrons (current)
through the circuit.
If the ammeter measures a current, and the bulb
glows, then the solution conducts.
If the ammeter fails to measure a current, and the
bulb does not glow, the solution is non-conducting.

6. Definition of Electrolytes and Nonelectrolytes
An electrolyte is:
A substance whose aqueous solution conducts
an electric current.
A nonelectrolyte is:
A substance whose aqueous solution does not
conduct an electric current.
Try to classify the following substances as
electrolytes or nonelectrolytes…

7. Electrolytes?
Pure water
Tap water
Sugar solution
Sodium chloride solution
Hydrochloric acid solution
Lactic acid solution
Ethyl alcohol solution
Pure, solid sodium chloride

8. Answers… ELECTROLYTES: NONELECTROLYTES: Tap water (weak) NaCl solution
  HCl solution
  Lactate solution (weak)
  Pure water
  Sugar solution
  Ethanol solution
  Pure, solid NaCl
But why do some compounds conduct electricity in
solution while others do not…?

9. Ionic CompoundsDissociate
NaCl(s) 
Na+(aq) + Cl-(aq)
AgNO3(s) 
Ag+(aq) + NO3-(aq)
MgCl2(s) 
Mg2+(aq) + 2 Cl-(aq)
Na2SO4(s) 
2 Na+(aq) + SO42-(aq)
AlCl3(s) 
Al3+(aq) + 3 Cl-(aq)

10. Some covalent compounds IONIZE in solution
Covalent acids form ions in solution, with the
help of the water molecules.
For instance, hydrogen chloride molecules,
which are polar, give up their hydrogens to
water, forming chloride ions (Cl-) and
hydronium ions (H3O+).

11. Strong acids such as HCl are completely ionized in solution.
Other examples of strong acids include:
Sulfuric acid, H2SO4
Nitric acid, HNO3
Hydriodic acid, HI
Perchloric acid, HClO4
Hydrobromic acid, HBr

12. Weak acids such as lactic acid usually ionize less than 5% of the time.
Many of these weaker acids
are “organic” acids
that contain a “carboxyl”
group.
The carboxyl group does not easily give up its
hydrogen.

13. Because of the carboxyl group, organic acids are sometimes called “carboxylic acids”.
Other organic acids and their sources include:
Citric acid – citrus fruit
Malic acid – apples
Butyric acid – rancid butter
Amino acids – protein
Nucleic acids – DNA and RNA
Ascorbic acid – Vitamin C
This is an enormous group of compounds; these
are only a few examples.

14. However, most covalent compounds do not ionize at all in solution.
Sugar (sucrose – C12H22O11),
and ethanol (ethyl alcohol – C2H5OH) do not
ionize -
That is why they are nonelectrolytes!

15. Molarity
The concentration of a solution measured in moles of solute per liter of solution.
mol = M L

16. Preparation of Molar Solutions
Problem: How many grams of sodium chloride are needed to prepare 1.50 liters of M NaCl solution?
Step #1: Ask “How Much?” (What volume to prepare?)
Step #2: Ask “How Strong?” (What molarity?)
Step #3: Ask “What does it weigh?” (Molar mass is?)
1.500 L
0.500 mol
58.44 g
= 43.8 g
1 L
1 mol

17. Serial Dilution
It is not practical to keep solutions of many different concentrations on hand, so chemists prepare more dilute solutions from a more concentrated “stock” solution.
Problem: What volume of stock (11.6 M) hydrochloric acid is needed to prepare 250. mL of 3.0 M HCl solution?
MstockVstock = MdiluteVdilute
(11.6 M)(x Liters) = (3.0 M)(0.250 Liters)
x Liters = (3.0 M)(0.250 Liters)
11.6 M
= L

18. Single Replacement Reactions
A + BX  AX + B
BX + Y  BY + X
Replacement of:
Metals by another metal
Hydrogen in water by a metal
Hydrogen in an acid by a metal
Halogens by more active halogens

19. The Activity Series of the Metals
  Lithium
  Potassium
  Calcium
  Sodium
  Magnesium
  Aluminum
  Zinc
  Chromium
  Iron
  Nickel
  Lead
  Hydrogen
  Bismuth
  Copper
  Mercury
  Silver
  Platinum
  Gold
Metals can replace other metals
provided that they are above the
metal that they are trying to
replace.
Metals above hydrogen can
replace hydrogen in acids.
Metals from sodium upward can
replace hydrogen in water

20. The Activity Series of the Halogens
  Fluorine
  Chlorine
  Bromine
  Iodine
Halogens can replace other
halogens in compounds, provided
that they are above the halogen
that they are trying to replace.
2NaCl(s) + F2(g) 
2NaF(s) + Cl2(g)
???
MgCl2(s) + Br2(g) 
No Reaction
???

21. Solubility Rules – Mostly Soluble
Ion
Solubility
Exceptions
NO3-
Soluble
None
ClO4-
Na+ K+
NH4+
Cl-, I-
Pb2+, Ag+, Hg22+
SO42-
Ca2+, Ba2+, Sr2+, Pb2+, Ag+, Hg2+

22. Solubility Rules – Mostly Insoluble
Ion
Solubility
Exceptions
CO32-
Insoluble
Group IA and NH4+
PO43-
OH-
Group IA and Ca2+, Ba2+, Sr2+
S2-
Groups IA, IIA, and NH4+

23. Oxidation and Reduction (Redox)
  Electrons are transferred
  Spontaneous redox rxns can transfer energy
  Electrons (electricity)
  Heat
  Non-spontaneous redox rxns can be made to happen with electricity

24. Oxidation and Reduction
An old memory device for oxidation and reduction goes like this…
LEO says GER
Lose Electrons = Oxidation
Gain Electrons = Reduction

25. Oxidation Reduction Reactions (Redox)
Each sodium atom loses one electron:
Each chlorine atom gains one electron:

26. LEO says GER :
Lose Electrons = Oxidation
Sodium is oxidized
Gain Electrons = Reduction
Chlorine is reduced

27. Rules for Assigning Oxidation Numbers Rules 1 & 2
The oxidation number of any uncombined element is zero
2. The oxidation number of a monatomic ion equals its charge

28. Rules for Assigning Oxidation Numbers Rules 3 & 4
3. The oxidation number of oxygen in
compounds is -2
4. The oxidation number of hydrogen in compounds is +1

29. Rules for Assigning Oxidation Number Rule 5
5. The sum of the oxidation numbers in the formula of a compound is 0
2(+1) + (-2) = 0
H O
(+2) + 2(-2) + 2(+1) = 0
Ca O H

30. Rules for Assigning Oxidation Numbers Rule 6
6. The sum of the oxidation numbers in the
formula of a polyatomic ion is equal to
its charge
X + 4(-2) = -2
S O
X + 3(-2) = -1
N O
 X = +5
 X = +6

31. Reducing Agents and Oxidizing Agents
  The substance reduced is the oxidizing agent
  The substance oxidized is the reducing agent
Sodium is oxidized – it is the reducing agent
Chlorine is reduced – it is the oxidizing agent

32. Trends in Oxidation and Reduction
Active metals:
  Lose electrons easily
  Are easily oxidized
  Are strong reducing agents
Active nonmetals:
  Gain electrons easily
  Are easily reduced
  Are strong oxidizing agents

33. Redox Reaction Prediction #1
Important Oxidizers
Formed in reaction
MnO4- (acid solution)
MnO4- (basic solution)
MnO2 (acid solution)
Cr2O72- (acid)
CrO42-
HNO3, concentrated
HNO3, dilute
H2SO4, hot conc
Metallic Ions
Free Halogens
HClO4
Na2O2
H2O2
Mn(II)
MnO2
Cr(III)
NO2 NO
SO2
Metallous Ions
Halide ions
Cl-
OH- O2

34. Redox Reaction Prediction #2
Important Reducers
Formed in reaction
Halide Ions
Free Metals
Metalous Ions
Nitrite Ions
Sulfite Ions
Free Halogens (dil, basic sol)
Free Halogens (conc, basic sol)
C2O42-
Halogens
Metal Ions
Metallic ions
Nitrate Ions
SO42-
Hypohalite ions
Halate ions
CO2

35. Not All Reactions are Redox Reactions
Reactions in which there has been no change in oxidation number are not redox rxns.
Examples: