1. Intro to Chemical Reactions p74
Chapter 11
Intro1
Intro2
Warm up: Could we survive with out chemical reactions? Why or why not?

2. P.74 Definition: Chemical reactions alter the molecular structure of the substances involved. video
Indications of a chemical change:
1. Evolution of heat and light.
2. Production of a gas.
3. Formation of a precipitate (solid).
4. Color change.
5. odor change

3. Chemical Equations Used to represent chemical reactions (rxn).
must contain the correct formulas
law of conservation of mass must be satisfied.

4. Chemical Equations video
2C2H2(g) + 5O2(g)  4CO2(g) + 2H2O(g)
Reactants Products
* is read as “yield” (also produce or form)
*number in front of formula is called coefficient. (used in balancing)
*(g) the state of matter

5. The following is a list of symbols used in chemical equations:
heat Δ
= reversible rxn
(aq) = aqueous
(s) = solid phase
(l) = liquid phase
(g) = gas phase
or = reactants
are heated
= pressure at which
rxn took place
= temp at which rxn took place
= formula of catalyst
(manganese dioxide)
2 atm 0˚
MnO2

6. Chemical Reaction Acrostic p73
Make an acrostic on page 73 using the word:
REACTION
Try to use only one word and try to use the first letter for each word.

7. Balancing Chemical Equations p76
Warm up: What are the indications for a chemical reaction?
Diatomic Molecules:
7 elements that are bound to other elements in compounds or to themselves but are never found alone.
These elements are: H2, N2, O2, F2, Cl2, Br2, and I2.

8. “BIG 7”
The 7 diatomics appear in blue

9. Balancing equations p76 Balancing Steps:
Step 1:Write a formula equation
Step 2:
a. Balance the different atoms one at a time changing only the coefficients.
b. Balance unique atoms first.
c. Balance polyatomic ions if they appear on both sides as single units.
d. Balance H atoms and O atoms last.

10. Balancing Chemical Equations p76
EX: Liquid water breaks down into hydrogen and oxygen gases when heated.
H2O(l)  H(g) + O(g)

11. Avoid the following when balancing: p76
Writing incorrect chemical formulas.
Balancing equations by changing the subscripts.
Coefficients not in the smallest whole number ratio.
EX: 4H2O(l)  4H2(g) + 2O2(g)
* Factor out the LCM.
video

12. Practice Balancing p75 Zn(s) + HCl(aq)  ZnCl2(aq) + H2(g)
2. HNO3(aq) + Mg(OH)2(s) 
Mg(NO3)2(aq) + H2O(l)
2HNO3(aq) + Mg(OH)2(s) 
Mg(NO3)2(aq) + 2H2O(l)

13. Types of Chemical Reactions p78 video
Warm up: how many types of chemical rxns did you see in the video?
1. Synthesis (combination, formation) rxn
2. Decomposition rxn
3. Single replacement (displacement) rxn
4. Double replacement (displacement) rxn
5. Combustion rxn

14. Synthesis Rxns p78 (formation,combination)
two or more substances combine to form a new compound.
A + X  AX
EX: 2Mg(s) + O2(g)  2MgO(s)
video

15. Decomposition Rxns AX  A + X
a single compound produces two or more simpler substances.
AX  A + X
EX: 2H2O(l)  2H2(g) + O2(g)
video

16. Single Replacement Rxs
one element replaces a similar element in a compound.
A + BX  AX + B
EX: 3Fe(s) +4H2O(l)  Fe3O4(s) + 4H2(g)
video

17. Wow!
He’s got SWAG!
Stupid Jerk!
Mg(s) HCl(aq)  MgCl2(aq) + H2(g)

19. Using the Activity Series of Elements p77
Use the activity series to predict whether each of the following rxns will occur:
1. Zn(s) + H2O(l)  Will Occur
2. Cu(s) + HCl(aq)  No Reaction
3. Cd(s) + Pb(NO3)2(aq)  Will Occur
4. Al(s) + ZnCl2(aq)  Will Occur
5. Ca(s) + NaCl(s)  Will Occur
6. Co(s) + NaCl(s)  No Reaction

20. Double Replacement Rxns p80
Warm up: explain how one uses the activity series to predict if a reaction will occur.
the ions of two compounds exchange places
AX + BY  AY + BX
EX: 2KI(aq) + Pb(NO3)2(aq) 
PbI2(s) + 2KNO3(aq)
video

21. Combustion Rxns CxHY + O2  CO2 + H2O
a hydrocarbon combines with oxygen, releasing energy in the form of heat and light.
CxHY + O2  CO2 + H2O
EX: C3H8(g) + 5O2(g)  3CO2(g) + 4H2O(g)
*combustion of hydrocarbons always result in the formation of CO2 and water.
video

22. Identifying Rxns p79
Use your knowledge of rxn types to classify the following rxns:
NH3(g) + HCl(g)  NH4Cl(s)
C2H5OH(l) + O2(g)  CO2(g) + H2O(g)
2KClO3(s)  2KCl(s) + 3O2(g)
Zn + H2SO4  ZnSO4 + H2
S(s) + O2(g)  SO2(g)
AgNO3(aq) + NaCl(aq) 
AgCl(s) + NaNO3(aq)

23. Predicting Products p79
Use your knowledge of rxn types to predict the products of the following rxns:
Na + H2O 
Na2O + H2
HNO3 + Ca(OH)2 
Ca(NO3)2 + H2O
Mg + O2 
MgO

24. Predicting Products p79 Ca + Cl2  CaCl2 C6H14 + O2  CO2 + H2O
Br2 + KI 
KBr + I2
MgO + Pb 
No Reaction

25. Predict products p79 *Now, balance these rxns to make them correct.Δ
HgO 
Hg + O2
Na + Cl2 
NaCl
NaI + Cl2 
NaCl + I2
*Now, balance these rxns to make them correct.

26. Oxidation Reduction Reactions
“Redox”
LEO SAYS GER

27. Oxidation and Reduction (Redox)
Electrons are transferred
The oxidation number of atoms change

28. Rules for Assigning Oxidation Numbers:
any uncombined element is zero
2. a monatomic ion equals its charge

29. Rules for Assigning Oxidation Numbers:
3. oxygen in compounds is -2
4. hydrogen in compounds is +1

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

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

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

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

34. 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
video

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

36. 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