1. Advanced Reaction Topics

2. Advanced Reaction Topics
Reaction Rates
Redox Chemistry
Equilibrium
Acids and Bases

3. Reaction Rates

4. Reaction Rates Things that affect the rate of a reaction
Temperature
Increasing the temperature 10°C doubles the reaction rate (typically)
Concentration
Surface Area
Catalysts & Enzymes
Every reaction is different and has a different reaction rate.

5. Collision Theory
Reactions happen when molecules collide with each other
The reaction only happens IF:
They collide with enough energy
They collide with the right orientation.

6. How Do They Relate? Things that affect the rate of a reaction
Temperature
Increasing temperature increases the kinetic energy in a collision.
Kinetic energy is the energy of motion of an object
More collisions will have enough energy to have an effective collision

7. How Do They Relate? Concentration
Things that affect the rate of a reaction
Concentration
Increases the number of particles in the same volume and therefore the number of collisions
Surface Area
Increases the accessible area for collisions

8. How Do They Relate? Catalysts and Enzymes
Things that affect the rate of a reaction
Catalysts and Enzymes
Lower the amount of energy needed for a reaction to take place, so more effective collisions result

9. Redox Chemistry

10. Electrolysis Run a current through water.
Splits water into hydrogen and oxygen
2H2O  2H2 + O2

11. Oxidation Numbers
Describes the relative amount of electrons associated with a particular atom
Has no actual physical meaning (for the most part)
Only an electron bookkeeping method.

12. Finding Oxidation Numbers
Every uncombined element in its natural state has an oxidation number of zero.
The oxidation number of a monatomic ion is its charge.

13. Finding Oxidation Numbers
Remember the following:
Fluorine in a compound is always -1
Hydrogen is a +1 normally in a compound. It is -1 when a hydride.
Oxygen is almost always -2 in a compound unless it is a peroxide (-1)
The sum of the individual oxidation numbers on every atom in a species is equal to the overall charge on that species.

14. Oxidation Numbers Practice
Give the oxidation number of every element in the following compounds.
CHF3

15. Oxidation Numbers Practice
Give the oxidation number of every element in the following compounds.
BaCl2

16. Oxidation Numbers Practice
Give the oxidation number of every element in the following compounds.
KNO3

17. Oxidation Numbers Practice
Give the oxidation number of every element in the following compounds.
S2O32-

18. Oxidation Numbers Practice
Give the oxidation number of every element in the following compounds. P4

19. Oxidation Numbers Practice
Give the oxidation number of every element in the following compounds.
(NH4)2C2O4

20. Oxidation Numbers WB Practice
Give the oxidation number of every element in the following compounds. CaS MgF2 HNO3 H2O2 Na2S2O3

21. Vanadium Oxidation States
Vanadium oxidation states.mov

22. Uses of Redox Chemistry
Batteries
Harnessed flow of electrons driven by redox reaction.
Car battery

23. Alkaline Batteries

24. Electroplating

25. Corrosion

26. Equilibrium

27. Fishbowl Demo Rules: No “goal-tending”
Get water in beaker, not around it

28. Fishbowl Demo
What are the characteristics once it reaches equilibrium?
The amount of “reactants” and “products” is not changing
“Reactions” are still occurring in both the forward and reverse direction.
The rate of the “reactions” is the same at equilibrium

29. Characteristics of Equilibrium
The amounts of the reactants and products do not change while the system is at equilibrium.

30. Characteristics of Equilibrium
Consider: N2 + 3H2 ⇌ 2NH3
Notice the double half arrows

31. Characteristics of Equilibrium
The forward and reverse reactions still both occur but at the same rate.
For this reason, equilibrium can also be called dynamic equilibrium

32. Equilibrium Constants
We can calculate the equilibrium constant for a reaction at equilibrium by measuring the concentrations of each species involved, then determining the ratio of products to reactants.
Keq>1 means that the reaction favors the products
Keq<1 means that the reaction favors the reactants

33. Equilibrium Constants

34. Practice Problem

35. Practice Problem

36. Making Changes to an Equilibrium System
How does changing the amount of one species affect the equilibrium?
An equilibrium system must respond to changes.
A dynamic system must respond to any changes made.

37. Le Chatelier's Principle
“When a stress is placed on an equilibrium system, the equilibrium will shift to relieve that stress.”
The equilibrium may shift to the right
To make more Products
To reduce the amount of Reactants
The equilibrium may shift to the left
To make more Reactants
To reduce the amount of Products

38. Le Chatelier's Principle
CoCl42– + 6H2O ⇌ Co(H2O) Cl–
(blue) (pink)
exothermic
What is the stress on the equilibrium if 12M HCl is added?
Which way does the equilibrium shift to relieve the stress? Why?
What will it look like?

39. Le Chatelier's Principle
CoCl42– + 6H2O ⇌ Co(H2O) Cl–
(blue) (pink)
exothermic
What is the stress on the equilibrium if H2O is added?
Which way does the equilibrium shift to relieve the stress? Why?
What will it look like?

40. Le Chatelier's Principle
CoCl42– + 6H2O ⇌ Co(H2O) Cl–
(blue) (pink)
exothermic
What is the stress on the equilibrium if Ag+ is added?
Which way does the equilibrium shift to relieve the stress? Why?
What will it look like?

41. Le Chatelier's Principle
CoCl42– + 6H2O ⇌ Co(H2O) Cl–
(blue) (pink)
exothermic
What is the stress on the equilibrium if heat is added?
Which way does the equilibrium shift to relieve the stress? Why?
What will it look like?

42. Le Chatelier's Principle
CoCl42– + 6H2O ⇌ Co(H2O) Cl–
(blue) (pink)
exothermic
What is the stress on the equilibrium if heat is removed (cooling)?
Which way does the equilibrium shift to relieve the stress? Why?
What will it look like?

43. Le Chatelier's Principle
2NO2(g) ⇌ N2O4(g)
brownish red colorless
exothermic
If we cool the gasses which way does the equilibrium shift?
Why?
What will it look like?

44. Le Chatelier's Principle
2NO2(g) ⇌ N2O4(g)
brownish red colorless
exothermic
If we warm the gasses which way does the equilibrium shift?
Why?
What will it look like?

45. Le Chatelier's Principle
2NO2(g) ⇌ N2O4(g)
brownish red colorless
exothermic
If we release pressure on the gasses which way does the equilibrium shift?
Why?
What will it look like?

46. Acids and Bases

47. Hydrochloric Acid HCl(aq) What type of compound is it?
What type of electrolyte is hydrochloric acid?

48. Hydrochloric Acid Why does it light up?
What must be present in solution?
Is hydrochloric acid an ionic compound?
No. It is in a small subset of covalent compounds.

49. Hydrochloric Acid It must be making some ions in solution
What are the ions?
HCl + H2O  H3O+(aq) + Cl-(aq)

50. Hydrochloric Acid H3O+ is called the hydronium ion
Things that make hydronium ions in water are called acids.

51. A Word About Hydronium Depending on how you look at it acids make
H+ - hydrogen ion
H3O+ - hydronium ion
The two are interchangable
H+ + H2O  H3O+
Anytime you see one it can mean the other.

52. Common Acids Hydrochloric acid (HCl) Muriatic acid
Sulfuric acid (H2SO4)
Battery acid
Nitric acid (HNO3)
Acetic acid (HC2H3O2)
Vinegar
Phosphoric acid (H3PO4)
Citric Acid
Lactic Acid
Ascorbic Acid
Vitamin C
Acetylsalicylic Acid
Aspirin
Stearic Acid

53. Common Bases Ammonia Sodium hydroxide Sodium hypochlorite
Bleach
Sodium hydrogen carbonate
Baking Soda
Calcium carbonate
Chalk
Tums
Sodium hydroxide
Lye, Caustic Soda
Calcium hydroxide
Lime
Magnesium hydroxide
Milk of magnesia

54. Acids and Bases Arrhenius Definitions
Arrhenius Acid – a substance that dissociates and produces hydronium ions in water
Arrhenius Base – a substance that dissociates and produces hydroxide ions in water

55. Acids and Bases Brønsted-Lowry Definitions
Brønsted-Lowry Acid – a substance that donates a hydrogen ion (H+) (a proton)
Brønsted-Lowry Base – a substance that accepts a hydrogen ion (H+) (a proton)

56. Acid and Base Definitions
Overlap between the acid definitions
HCl + H2O  Cl- + H3O+
HCl dissociates and produces hydronium ions
Arrhenius Acid
HCl donates an H+ to water
Brønsted-Lowry Acid
All Arrhenius Acids are Brønsted-Lowry Acids and vice versa.

57. Acid and Base Definitions
Relations between the base definitions are not as simple.
NaOH dissolves in water to form Na+ and OH-
Arrhenius Base
NaOH + H+  Na+ + H2O
Brønsted-Lowry Base
Hydroxides are both Arrhenius and Brønsted-Lowry Bases.

58. Acid and Base Definitions
Non-hydroxide bases can’t be Arrhenius bases
No hydroxide obviously…
Non-hydroxide bases will be Brønsted-Lowry bases
CO32- + H+  HCO3-
NH3 + H+  NH4+

59. Acid and Base Definitions
Arrhenius acids and bases are tied to water
Brønsted-Lowry acids and bases are not.
Brønsted-Lowry can be used to describe reactions in the gas phase or in other solvents besides water.

60. Acid-Base Definitions
Monoprotic acid – an acid that has one ionizable hydrogen
HCl, HNO3
Diprotic acid – an acid that has two ionizable hydrogens
H2SO4

61. Acid-Base Definitions
Triprotic acid – an acid that has three ionizable hydrogens
H3PO4
What kind of acid is acetic acid, HC2H3O2?
Monoprotic
Typically only hydrogens written first are ionizable.

63. Autolysis of Water Water spontaneously splits itself 2H2O ⇌ H3O+ + OH–
An equilibrium system.
Makes equal parts hydronium and hydroxide
Equal parts acid and base
Water is neutral.

64. Autolysis of Water We will use brackets to represent molarity
[H3O+] is the molarity of the hydronium ion.
When acids and bases are dissolved in water [H3O+][OH–] = Kw = 1x10-14

65. Acid Base Reactions Look on your reference table
Most acid base reactions fall under the category of double replacement; however, there are some that do not.
We are only going to consider the ones that are double replacement!

66. Acid Base Reactions Transfer of hydrogen ions (H+)
Acid Base Neutralization Reaction
HA + B  A + HB
Transfer of hydrogen ions (H+)
Hydrochloric acid and sodium hydroxide solutions are mixed

67. Acid Base Reactions Transfer of hydrogen ions (H+)
Acid Base Neutralization Reaction
HA + B  A + HB
Transfer of hydrogen ions (H+)
Acetic acid and barium hydroxide solutions are mixed.

68. Acid Base Reactions Transfer of hydrogen ions (H+)
Acid Base Neutralization Reaction
HA + B  A + HB
Transfer of hydrogen ions (H+)
Ammonia and sulfuric acid solutions are mixed

69. Acid Base Reactions Transfer of hydrogen ions (H+)
Acid Base Neutralization Reaction
HA + B  A + HB
Transfer of hydrogen ions (H+)
Hydrochloric acid and sodium sulfide solutions are mixed.

70. Acids Hydrochloric acid Acetic acid Is it an electrolyte?
Why is it an electrolyte?
Acetic acid
Why doesn’t it light up as much as hydrochloric acid?

71. Strength of Acids and Bases
Hydrochloric acid completely dissociates
HCl + H2O  H3O+ + Cl-
Acetic acid doesn’t make as many ions
Acetic acid partially dissociates
HC2H3O2 + H2O ⇌ H3O+ + C2H3O2–
Around 0.5% of acetic acid molecules make hydronium ions
Reactant side is very favored.

72. Strength of Acids and Bases
Strong acid or base – an acid or base that completely reacts with water to form hydronium ions or hydroxide ions.
Strong acids – hydrochloric, sulfuric, nitric
Strong bases – LiOH, NaOH, KOH, RbOH, CsOH, Ca(OH)2, Sr(OH)2, Ba(OH)2

73. Strength of Acids and Bases
Weak acid or base – an acid or base that partially reacts with water to form hydronium ions or hydroxide ions.
Weak acids – everything except the strong acids
Weak bases – everything except the strong bases

74. Strong Acid
Weak Acid

75. Strength of Acids and Bases
Strength does not describe concentration
Consider
A bottle of “glacial” acetic acid (99%)
A bottle of concentrated sulfuric acid (98%)
Both have (nearly) the same concentration
Acetic acid will not ionize as much in water as sulfuric acid will
Acetic acid is a “weak” acid

77. Concentration of Acids
If not all acids completely dissociate in water
The concentration of the acid molecules is different for every acid
The concentration of the hydronium ion in different acids is different
Need a system that describes the concentration of acids.

78. pH pH = -log [H3O+] Also define a relationship for the amount of base
pOH = -log [OH–]
How do you reverse a log?
10-pH = [H3O+]
10-pOH = [OH–]

79. How are pH and pOH related?
Kw = [H3O+][OH–]
log Kw = log ([H3O+][OH–])
log Kw = log [H3O+] + log [OH–]
log 1x10-14 = log [H3O+] + log [OH–]
-14 = log [H3O+] + log [OH–]
14 = -log [H3O+] + -log [OH–]
14 = pH + pOH

81. Practice Problems
What is the pH of a solution with [H+] of 1.0x10-3 M?

82. Practice Problems
What is the pOH of a solution with [H+] of 1.0x10-3 M?

83. Practice Problems
What is the [OH-] of a solution with a pH of 9.00?

84. Practice Problems
What is the [OH-] of a solution with an [H3O+] concentration of 1.0x10-5 M?

85. Practice Problems
What is the pH of a solution with a hydronium ion concentration of x10-4M?

86. Practice Problems
What is the pOH of a solution that has a hydronium ion concentration of x10-8 M?

87. Indicators Colored compounds that are sensitive to changes in pH
Indicators will change color based on how acidic or basic the conditions around it are
Chemical reaction with the acids or bases

89. Universal Indicator
Universal Indicator is a mixture of different indicators.
Resulting color depends on each of the four indicator’s states

91. Redox Chemistry

92. Electrolysis Run a current through water.
Splits water into hydrogen and oxygen
2H2O  2H2 + O2

93. Oxidation Numbers
Describes the relative amount of electrons associated with a particular atom
Has no actual physical meaning (for the most part)
Only an electron bookkeeping method.

94. Finding Oxidation Numbers
Every uncombined element in its natural state has an oxidation number of zero.
The oxidation number of a monatomic ion is its charge.

95. Finding Oxidation Numbers
Remember the following:
Fluorine in a compound is always -1
Hydrogen is a +1 normally in a compound. It is -1 when a hydride.
Oxygen is almost always -2 in a compound unless it is a peroxide (-1)
The sum of the individual oxidation numbers on every atom in a species is equal to the overall charge on that species.

96. Oxidation Numbers Practice
Give the oxidation number of every element in the following compounds.
CHF3

97. Oxidation Numbers Practice
Give the oxidation number of every element in the following compounds.
BaCl2

98. Oxidation Numbers Practice
Give the oxidation number of every element in the following compounds.
KNO3

99. Oxidation Numbers Practice
Give the oxidation number of every element in the following compounds.
S2O32-

100. Oxidation Numbers Practice
Give the oxidation number of every element in the following compounds. P4

101. Oxidation Numbers Practice
Give the oxidation number of every element in the following compounds.
(NH4)2C2O4

102. Oxidation and Reduction
Oxidation - chemical process involving the loss of electrons.
Reduction – chemical process involving gaining electrons.
LEO the lion goes GER
OIL RIG

103. Oxidation and Reduction
Consider:
MnO4- + C2O42- + H+  Mn2+ + CO2 + H2O
What element has been reduced?
What element has been oxidized?
What species reacted with the element that was reduced?
This is the reducing agent.
What species reacted with the element that was oxidized?
This is the oxidizing agent.

105. Vanadium Oxidation States
Vanadium oxidation states.mov

106. I- + ClO- + H+  I3- + Cl- + H2O
Practice
Identify the element oxidized, the element reduced, the species that is the oxidizing agent, and the species that is the reducing agent in:
I- + ClO- + H+  I3- + Cl- + H2O

107. Practice
Identify the element oxidized, the element reduced, the species that is the oxidizing agent, and the species that is the reducing agent in:
H+ + Cr2O72- + C2H5OH Cr3+ + CO2 +H2O

108. Uses of Redox Chemistry
Batteries
Harnessed flow of electrons driven by redox reaction.
Car battery
PbO2(s) + Pb(s) + 2H2SO4  2PbSO4(s) + 2H2O

109. Alkaline Batteries
Zn + 2MnO2  ZnO + Mn2O3

110. Fuel Cells
2H2 + O2  2H2O

111. Electroplating

112. Corrosion