1. CHEMICAL REACTIONS & EQUATIONS

2. Chemical Reactions

3. Chemical Reactions
Process in which one or more substances are converted into new substances with different physical and chemical properties
For example, a yellow solid precipitate, lead iodide (PbI2), forms from the mixture of two clear liquids, potassium iodide (KI) and lead nitrate (Pb(NO3)2).

4. Word Equation
Hydrogen + Oxygen
Water + Energy
Reactants
Products

5. Balanced Formula Equations2
H2 (g) + O2 (g) 1 2
H2O (l)
Why?
To give a quantitative, as well as qualitative information.

6. 2H2 (g) + 1O2 (g)
2H2O (l)
2 Molecules Water
2 Molecules H + 1 molecule O +
2 Moles H2 + 1 Mole O2
2 Moles Water
4 g
32 g +
36 g

7. Rules for Balancing Equations
1. Write correct formulas for all reactants and products.
Use the symbols for elements: Iron = Fe
Don’t forget diatomic elements travel in pairs!
H2, N2, O2, F2, Cl2, Br2, I2

8. Rules for Balancing Equations
2. Obey the LAW OF CONSERVATION OF MASS.
Same number of each kind of atom on both sides of the equation.
25g +
25g +
50 g
50 g +
150 g ?g

9. How to Balance an Equation
3. To balance atoms of reactants and products, change ONLY the coefficients.
4. Do NOT change the chemical formula to balance numbers of atoms.
Numbers IN FRONT of the formulas
NOTE: Subscripts are lower numbers in formula
4 Al2O3
Coefficient
Subscripts

10. How to Balance an Equation cont.
5. Check your work by counting atoms of each element.
6. Check to see that the coefficients are in the lowest whole number ratio.
2H2O (l)
2H2 (g) + 1O2 (g)
4 Hydrogen
4 Hydrogen
2 Oxygen
2 Oxygen

11. Practice Balancing These Equations
Ca O2
CaO 2 1 2
1 Ca
1 Ca
2 O
1 O
*Hint: Start by making the uneven side even.
2 O
2 O
1 Ca
2 Ca
2 Ca
2 Ca
2 O
2 O
2 Ca, 2 O
2 Ca, 2 O

12. Practice 1 2 1 2 CH4 + O2 CO2 + H2O 2 O 3 O 4 O 4 O 1 C 1 C 4 H 4 H
*Hint: Start with the element that is split up: Oxygen.
Then, make uneven side even.
2 O
3 O
4 O
4 O
1 C
1 C
4 H
4 H
1 C, 4 H, 4 O
1 C, 4 H, 4 O

13. Practice Fe + Cl2 FeCl3 2 1 3 2 1 Fe 1 Fe 2 Cl 3 Cl 6 Cl 6 Cl 1 Fe

14. Practice 2 HgO Hg + O2 2 1 1 3 2 Al + MnO Al2O3 + Mn 3 2 Al, 3 Mn, 3 O
Br NaI
NaBr I2 1 2
2 Br, 2 Na, 2 I
2 Br, 2 Na, 2 I
Do these on own 2
HgO
Hg O2 2 1
2 Hg, 2 O
2 Hg, 2 O

15. Coefficients Must Be in Lowest WHOLE Number!2 2 2 5 4 1
21/2 1
C2H O2
CO H2O
What number can you multiply 21/2 by to get
the smallest whole number? 2!
So, multiply the whole equation by 2 to get a properly
balanced equation.
4 C, 4 H, 10 O
4 C, 4 H, 10 O

16. You try. Multiply by 2! 8 C, 2O H, 26 O 8 C, 2O H, 26 O 1 13 61/2 8 410 5
C4H O2
CO H2O 2
Multiply by 2!
8 C, 2O H, 26 O
8 C, 2O H, 26 O

17. Classification of Chemical Reactions
1. Synthesis
2. Decomposition
3. Single Replacement
4. Double Replacement
5. Combustion (burning)

18. A B AB Synthesis Examples: 1 2 Cu + O2 CuO 1 H2CO3 CO2 + H2O
Two reactants combine to form a single product (compound). A B AB
One Product
Examples: 1 2
Cu O2
CuO 1
H2CO3
CO H2O

19. AB A B Decomposition Examples: 2 3 KClO3 KCl + O2 1 2 H2O2 H2O + O2
One reactant breaks down to form two or more products. AB A B
One Reactant
Examples: 2 3
KClO3
KCl O2 1 2
H2O2
H2O O2

20. A BC AC B Single Replacement Examples: 2 1 Mg + HCl MgCl2 + H2 2 1
One element replaces another from a compound A BC AC B
Examples: 2 1
Mg + HCl
MgCl H2 2 1
Cl KI
KCl I2

21. Double Replacement (ionic)
Ions in a solution combine to form a product that leaves the scene of the reaction AB CD AD CB
Example:
AgNO3 (aq) + NaCl (aq)
AgCl (s) + NaNO3 (aq)

22. More on Double Replacement
Precipitate (s), gas (g) or water (H2O) will form
AgNO3 (aq) + NaCl (aq)
AgCl (s) + NaNO3 (aq)
Actual reaction:
AgCl
Ag+1 + Cl-1
Don’t dwell (do it in depth later)
Spectator Ions:
Na+1 & NO3-1

23. What happens when you put AgNO3 and NaCl in water?
AgNO3 (aq) + NaCl(aq) AgCl(s) + NaNO3(aq)
AgNO3 (aq) + NaCl(aq) AgCl(s) + NaNO3(aq)
What happens when you put
AgNO3 and NaCl in water?
What happens when you put
AgNO3 and NaCl in water?

25. NaCl
AgNO3

26. NaCl
AgNO3

27. AgNO3
NaCl

28. AgNO3
NaCl

29. AgNO3
NaCl

30. AgNO3
NaCl

31. AgNO3
NaCl

32. Ag NO3
Na Cl

33. Ag+
NO3-
Na+
Cl-

34. Ag+
NO3-
Na+
Cl-

35. Ag+
NO3-
Cl-
Na+

36. NO3-
Ag+
Na+
Cl-

37. NO3-
Na+
Ag+
Cl-

38. NO3-
Na+
Ag+
Cl-

39. NO3-
Na+
Cl-
Ag+

40. Na+
NO3-
Cl-
Ag+

41. Na+
NO3-
Cl-
Ag+

42. Na+
NO3-
Ag+
Cl-

43. Na+
NO3-
Ag+
Cl-

44. Na+
NO3-
Ag+
Cl-

45. Na+
NO3-
Ag+
Cl-

46. NO3-
Na+
AgCl

47. Na+
NO3-
AgCl

48. Na+
NO3-
AgCl

49. Na+
NO3-
AgCl(s)
precipitate
AgCl

50. Na+
NO3-
AgCl(s)
precipitate
AgCl

51. Na+
NO3-
AgCl

52. NO3-
Na+
AgCl

53. NO3-
Na+
AgCl

54. Na+
NO3-
AgCl

55. Na+
NO3-
AgCl

56. Na+
NO3-
AgCl

57. Na+
NO3-
AgCl

58. Na+
NO3-
AgCl

59. Na+
NO3-
AgCl

60. AgNO3
NaCl
NaCl
NaCl
AgNO3
AgNO3
NaCl
NaCl
NaCl
AgNO3
AgNO3
AgNO3
AgNO3
NaCl

61. AgNO3
NaCl
NaCl
NaCl
AgNO3
AgNO3
NaCl
NaCl
NaCl
AgNO3
AgNO3
AgNO3
AgNO3
NaCl

62. AgNO3
NaCl
NaCl
NaCl
AgNO3
AgNO3
NaCl
NaCl
NaCl
AgNO3
AgNO3
AgNO3
AgNO3
NaCl

63. AgNO3
NaCl
NaCl
NaCl
AgNO3
AgNO3
NaCl
NaCl
NaCl
AgNO3
AgNO3
AgNO3
AgNO3
NaCl
Ag+
Na+
NO3-
Cl-

64. AgNO3
NaCl
NaCl
NaCl
AgNO3
NaCl
AgNO3
Ag+
Na+
NO3-
Cl-
Ag+
Cl-
NO3-
Na+
Na+
Ag+
NO3-
Cl-
AgCl

65. Ag+
Na+
NO3-
Cl-
Cl-
Cl-
Na+
Ag+
NO3-
NO3-
Ag+
Na+
NO3-
Ag+
Cl-
Na+
NO3-
Cl-
NO3-
Na+
Cl-
Na+
Ag+
Ag+
Cl-
Ag+
Cl-
Cl-
Ag+
Ag+
AgCl
AgCl
AgCl

66. Ag+
NO3-
Cl-
Ag+
NO3-
Na+
Ag+
Cl-
NO3-
Na+
NO3-
Ag+
Cl-
NO3-
NO3-
Na+
Cl-
Na+
Na+
Cl-
Ag+
Ag+
Na+
NO3-
Cl-
NO3-
Na+
Na+
Na+
Cl-
Ag+
AgCl
AgCl
AgCl
AgCl

67. Ag+
NO3-
Cl-
NO3-
Na+
NO3-
NO3-
Na+
Ag+
NO3-
NO3-
Cl-
Na+
Na+
Na+
Cl-
Ag+
Ag+
NO3-
Cl-
Na+
Na+
Na+
NO3-
Na+

68. NO3-
NO3-
Na+
NO3-
NO3-
Na+
NO3-
NO3-
Na+
Na+
Na+
Cl-
Ag+
Ag+
NO3-
Cl-
Na+
Na+
Na+
NO3-
Na+

69. NO3-
NO3-
Na+
NO3-
NO3-
Na+
NO3-
NO3-
Na+
Na+
Na+
Cl-
Ag+
Ag+
NO3-
Cl-
Na+
Na+
Na+
NO3-
Na+

70. NO3-
Na+
Na+
NO3-
Na+
NO3-
NO3-
NO3-
Na+
Na+
Na+
NO3-
NO3-
Na+
NO3-
Na+
Na+

71. NO3- Na+ NO3- NO3- Na+ Na+ Na+ NO3- NO3- Na+ Na+ Na+ NO3- NO3- Na+
AgCl(s)

72. NO3- Na+ Na+ NO3- Na+ NO3- NO3- NO3- Na+ Na+ Na+ NO3- NO3- Na+ NO3-
AgCl(s)

73. NO3- Na+ NO3- NO3- Na+ Na+ Na+ NO3- NO3- Na+ Na+ Na+ NO3- NO3- Na+
AgCl(s)

74. Combustion (burning) CxHy+ O2 CO2 + H2O C3H8 + O2 CO2 + H2O C2H2+ O2
Produces light and heat
CxHy+ O2
CO2 + H2O
Balance C 1st, then H, then O (because it splits up) 4 1
C3H O2 5
CO H2O 3 1 2
2.5 5 2 4 2 1
C2H2+ O2
CO H2O

75. Classification of Equations
SYNTHESIS AB A B Ca S
CaS
DECOMPOSITION AB A B
2HgO
2Hg O2

76. Classification of Equations
SINGLE
REPLACEMENT AB C A BC
2KCl
Br2
Cl2
2KBr
DOUBLE
REPLACEMENT AB CD AD CB
CaSO4
BaCl2
CaCl2
BaSO4

77. Putting it all together
1. Write the ions and element symbols.
2. Rewrite the correct formulas.
3. Balance the equation.
4. Identify the type of reaction.
BEFORE this they balance equation sheet (see star) then go back and ID type of equation
Iron (II) sulfide + Hydrochloric acid
Iron (II) chloride + Hydrogen sulfide

78. 1. Write the ions and element symbols
Iron (II) sulfide + Hydrochloric acid
Iron (II) chloride + Hydrogen sulfide
Fe+2S-2
+ HCl
Fe+2Cl-1
+ H+1S-2

79. 2. Rewrite the correct formula.
Fe+2S-2 + HCl
Fe+2Cl-1 + H+1S-2
FeS
+ HCl
FeCl2
+ H2S

80. 4. Identify the type of reaction.
3. Balance the equation. 1
FeS + HCl
FeCl H2S 2 1 1
4. Identify the type of reaction.
Insist on them writing oxidation states BEFORE formula.
Double Replacement!

81. Try this one. Ca0 + HCl Ca+2Cl-1 + H20 1 + HCl Ca CaCl2 + H2 2 1 1
1. Write the ions and element symbols.
2. Rewrite the correct formulas.
3. Balance the equation.
4. Identify the type of reaction.
Calcium + Hydrochloric acid
Calcium chloride+ Hydrogen
Ca0
+ HCl
Ca+2Cl-1
+ H20 1
+ HCl Ca
CaCl2 H2 2 1 1
Single Replacement!

82. Try this one. Zn+2 (OH)-1 Zn+2O-2 + H2O Zn(OH)2 ZnO + H2O 1 1 1
1. Write the ions and element symbols.
2. Rewrite the correct formulas.
3. Balance the equation.
4. Identify the type of reaction.
Zinc hydroxide
Zinc oxide+ water
Zn+2
(OH)-1
Zn+2O-2
+ H2O
Zn(OH)2
ZnO H2O 1 1 1
Maybe stop here and go on own with worksheet (depend on how they handle it).
Decomposition!

83. Try this one. N20 + O20 N+2O-2 1 N2 + O2 NO 1 2 Synthesis! Nitrogen
1. Write the ions and element symbols.
2. Rewrite the correct formulas.
3. Balance the equation.
4. Identify the type of reaction.
Nitrogen
Nitrogen oxide
+ Oxygen
N20
+ O20
N+2O-2 1
N O2 NO 1 2
Synthesis!

84. Activity Series of the Elements: Table LLi Rb K Ba Sr Ca Na Mg Al Mn Zn Cr Fe Cd Co Ni Sn Pb H2 Sb Bi Cu Hg Ag Pt Au
Replaces H
from water
Nonmetals F2 Cl2 Br2 I2
Replaces H
from acids
Most Active
Most Active
Least Active
Least Active
Metals replace metals or H
Nonmetals replace nonmetals
*REPLACE FROM OWN COLUMN

85. Making Predictions: Single Replacement Rxn
1. Write symbol and ions (for compounds) and predict products.
2. Rewrite correct formulas.
3. Use activity series to tell if rxn occurs and why.
4. Balance equation.
Pepsi commercial
Aluminum + Nickel (II) chloride ?

86. 1. Write symbols & ions and predict products.
Aluminum + Nickel (II) chloride ?
Al0
+ Ni+2Cl-1
Al+3Cl-1
+ Ni0
2. Rewrite correct formulas. Al
+ NiCl2
AlCl3
+ Ni

87. 3. Use the activity series to tell if the rxn occurs and why.
Yes, Al is more active than Ni. 2 Al
NiCl2 3 2
AlCl3 Ni 3
4. Balance equation.

88. Now try this one. Ca0 + Co+3(NO3)-1 Ca+2(NO3)-1 + Co0 3 3 2 Ca(NO3)2
1. Write symbol and ions (for compounds) and predict products.
2. Rewrite correct formulas.
3. Use activity series to tell if rxn occurs and why.
4. Balance equation.
Calcium + Cobalt (III) nitrate ?
Ca0
+ Co+3(NO3)-1
Ca+2(NO3)-1
+ Co0 3 3 2
Ca(NO3)2 Ca 2
+ Co
+ Co(NO3)3
Yes, Ca is more active than Co.

89. Now try this one. Br20 + Rb+1I-1 Rb+1Br-1 + I20 1 2 RbBr + I2 1 Br2
1. Write symbol and ions (for compounds) and predict products.
2. Rewrite correct formulas.
3. Use activity series to tell if rxn occurs and why.
4. Balance equation.
Bromine + Rubidium Iodide ?
Br20
+ Rb+1I-1
Rb+1Br-1
+ I20 1 2
RbBr I2 1
Br2
RbI 2
Yes, Br is more active than I.

90. Making Predictions: Double Replacement Rxn
Double Replacements will only complete when one or more of these events occur:
1. Water forms (H2O)
2. A gas forms (g)
3. A precipitate (s) forms
Do “Chapter 9 Double Replacement Reactions” first two together, rest on own.

91. Let’s try a couple Does the reaction occur? Does the reaction occur?
Ba(OH)2 (aq) + H2SO4(aq)
BaSO4(aq) + H2O(l)
Does the reaction occur?
YES; water is formed.
What are the spectator ions?
(The ions not involved in forming water, gas, or precipitate)
Ba+2 & SO4-2
Ca3(PO4)2(aq) + NaNO3(aq)
Na3(PO4)2(aq) + CaNO3(aq)
Does the reaction occur?
No; no water, gas or
precipitate is formed.

92. Potassium chromate + copper(II) hydroxide
1. Write symbols & ions and predict products.
Rewrite correct formulas and look up states of products on Table C.
K+1 (CrO4)-2
+ Cu+2(OH)-1
Cu+2(CrO4)-2
+ K+1(OH)-1
K2 (CrO4)
+ Cu(OH)2
Cu(CrO4)
(s)
+ K(OH)
(aq)
insoluble
on Table C
soluble
on Table C

93. Does a precipitate (s) form? 1 2
Potassium chromate + copper(II) hydroxide
3. Balance equation.
4. Does reaction occur?
Does water form?
Does a gas (g) form?
Does a precipitate (s) form? 1 2
K2CrO Cu(OH)2
CuCrO4 (s) KOH (aq) NO
Do “Double Replacement Reactions” predicting
Then single and double replacement reactions predicting NO
YES! THE RXN OCCURS!

94. Writing equations from a sentence
Write the equation for the production of oxygen gas and potassium chloride from the breakdown of potassium chlorate.
1. Potassium chlorate breaks down to form potassium chloride & oxygen
K+1Cl-1
+ O2 (g)
K+1(ClO3)-1
2. Rewrite the correct formulas.
KCl
+ O2 (g)
K(ClO3)
3. Balance the equation by changing the coefficients.
KCl O2 (g)
K(ClO3) 2 3

95. Barium hydroxide reacts with carbon dioxide to form barium carbonate and water.
Barium hydroxide reacts with carbon dioxide to form barium carbonate & water
Ba+2(OH)-1
+ CO2 (g)
Ba+2(CO3)-2
+ H2O(l)
Ba(OH)2
+ CO2 (g)
BaCO3
+ H2O(l)
Ba(OH)2
+ CO2 (g)
BaCO3
+ H2O(l) 1

96. CaC2 + H2O(l) + C2H2(g) Ca+2(OH)-1 CaC2 + H2O (l) Ca(OH)2 + C2H2(g) 1
Calcium carbide, CaC2, reacts with water to produce calcium hydroxide & ethyne gas, C2H2.
Calcium carbide reacts with water to produce calcium hydroxide & ethyne gas
CaC2
+ H2O(l)
+ C2H2(g)
Ca+2(OH)-1
CaC2
+ H2O (l)
Ca(OH)2
+ C2H2(g)
CaC2
+ H2O (l)
Ca(OH)2
C2H2(g) 1 2

97. Type of Reaction Definition Equation
Synthesis
Decomposition
Single Replacement
Double Replacement
Combustion
A hydrocarbon combines with oxygen to yield CO2 and water.
CxHy + O2  CO2 + H2O
Two or more elements or compounds combine to make a more complex substance
A + B → AB
Compounds break down
into simpler substances
AB → A + B
Occurs when one element replaces another one in a compound
AB + C → AC + B
Occurs when different atoms in two different compounds trade places
AB + CD → AC + BD

98. Classification of Equations
SYNTHESIS AB A B Ca S
CaS
DECOMPOSITION AB A B
2HgO
2Hg O2

99. Classification of Equations
SINGLE
DISPLACEMENT AB A BC C
2KCl
Br2
Cl2
2KBr
DOUBLE
DISPLACEMENT AB CD AD BC
CaSO4
BaCl2
CaCl2
BaSO4

100. Practice 1 CH4 + O2 CO2 + H2O 1 2 2 1 C 1 C 4 H 2 H 2 O 3 O 4 O 4 O
*Hint: Don’t make a move until you find the uneven side.
2 O
3 O
4 O
4 O
1 C
1 C
4 H
4 H
1 C, 4 H, 4 O
1 C, 4 H, 4 O

101. Practice 2 1 Na + H2O NaOH + H2 2 1 2 1 Na 1 Na 2 H 3 H 4 H 4 H 1 Na

102. Practice 6 C, 16 H, 20 O 6 C, 16 H, 20 O 6 8 2 C3H8 + O2 CO2 + H2O 1 110
1 C
3 C
6 C
6 C
2 H
16 H
16 H
16 H
2 O
20 O
Do together
20 O
20 O
6 C, 16 H, 20 O
6 C, 16 H, 20 O

103. Practice 1 2 Ba(OH)2 + HCl BaCl2 + H2O 1 1 2 1 Ba 1 Ba 2 O 1 O 2 O 2 O
1 Ba, 4 H, 2O, 2Cl
1 Ba, 4 H, 2O, 2Cl

104. Practice 3 2 1 Na3PO4 + Al2(SO4)3 Na2SO4 + AlPO4 2 1 3 Na 2 Na 6 Na
6 Ba, 2P, 20 O, 2 Al, 3 S
6 Ba, 2P, 20 O, 2 Al, 3 S

105. Practice 2 Ca(NO3)2 + KCl KNO3 + CaCl2 1 1 2 2 3 1 3
Al(OH) CaSO4
Al2(SO4) Ca(OH)2
2 Al, 12 O, 3 H, 3 Ca, 1 S
2 Al, 12 O, 3 H, 3 Ca, 1 S

106. Activity Series of the Elements: Table L
Metals Li Rb K Ba Sr Ca Na Mg Al Mn Zn Cr Fe Cd Co Ni Sn Pb H2 Sb Bi Cu Hg Ag Pt Au
Nonmetals F2
Cl2
Br2 I2