1. Chemical Reactions coefficients reactants products (Chapter 13)
What is chemical equilibrium? - George Zaidan and Charles Morton

2. Student Learning Objectives
Utilize chemical equations to determine the amounts of reactants, products, and energy change.
Characterize acids and bases.
Describe reactions involving oxygen.
6 Chemical Reactions That Changed History

3. How is a chemical equation balanced?
A chemical reaction is the process of forming new substances.
Atoms are combined to form molecules.
Molecules separate into atoms.
There must be the same numbers of each type of atom on each side of the equation.
Example: Al Br2  Al2Br6
What triggers a chemical reaction? - Kareem Jarrah

4. Practice
These Practice Problems are presented in class

5. Examples: Hydrogen & Water
There are always x 1023 atoms or molecules in 1 mole of a substance. The atomic mass number is equal to the grams/mole of that substance.
Avogadro’s Number
Examples: Hydrogen & Water
6.022 x 1023 particles
mole

6. Practice
1C(12.01
These Practice Problems are presented in class

7. What are exothermic and endothermic reactions?
The amount of chemical potential energy may change during a chemical reaction.
Exothermic
Reaction
Endothermic
Energy released
Energy absorbed
Reactants → higher PE
Products → higher PE

8. Activation Energy H2 + Cl2  2HCl

9. Bond Energy to Break = Bond Energy Released
Bond Strength
Bond Energy is the energy required to break 1 mole of bonds.
The net bond energy indicates whether the process was exothermic or endothermic.
Bond Energy to Break = Bond Energy Released

10. Examples
1) N2 + H2  N2H4 2) H4C2 + O2  CO2 + H2O

11. What can cause reaction rates to vary?
Temperature
Concentration
Surface area
Catalysts
A catalyst accelerates the reaction.
Provides different pathway
Lowers activation energy
Reappears as a product
How to speed up chemical reactions (and get a date) - Aaron Sams

12. Practice
These Practice Problems are presented in class

13. What is an acid? What is a base?
Acids contain H+ and H30+ ions, and are substances that donate hydrogen ions.
Bases contain hydroxide (OH−) ions, or are substances that accept a hydrogen ions.
Baking soda (NaHCO3)
Proton Donor
Proton Acceptor
Example: HCl + NaHCO3  H2CO3 + NaCl

14. Practice
These Practice Problems are presented in class

15. Strong acids & bases completely ionize in water.
HNO3 - nitric acid
HCl - hydrochloric acid
H2SO4 - sulfuric acid
LiOH - lithium hydroxide
NaOH - sodium hydroxide (lye)
KOH - potassium hydroxide (lye)
The strengths and weaknesses of acids and bases - George Zaidan and Charles Morton

16. The neutralization reaction of an acid and a base produces water and a salt.
HCl
 + 
NaOH 
H2O
NaCl
HBr
KOH
KBr

17. pH
Substance pH
Battery Acid
0.5
Stomach Acid
1.5 – 2.0
Cola
2.5
Orange Juice
3.5
Coffee
5.0
Milk
6.5
Human Blood
7.34 – 7.45
Hand Soap
9.0 – 10.0
Ammonia
11.5
Bleach
12.5
A substance that has an equal number of acid and base ions is neutral. (pH balanced) pH
Solution
1 to 6
Acidic 7
Neutral
8 to 14
Basic

18. Practice
These Practice Problems are presented in class

19. water + carbon dioxide  carbonic acid (H2CO3)
What is “acid rain”?
Acid Rain is moisture that has a pH of less than 5.
Rain, snow, sleet, or fog
Rainwater normally has a pH of 5.6 to 6.2
Acids may combine with dust (dry deposition)
Water naturally reacts with CO2 in the atmosphere, forming a weak acid.
water + carbon dioxide  carbonic acid (H2CO3)

20. Human-produced exhaust emissions of sulfur and nitrogen oxides form strong acids.
sulfates + water  sulfuric acid (H2SO4)
nitrates + water  nitric acid (HNO3)
Question: Where would you expect a higher level of acidity in the atmosphere, WY or CA? Why?

21. What is the result of an oxidation-reduction reaction?
Redox reactions involve a transfer of electrons, and often the addition or subtraction of oxygen.
The two processes, oxidation and reduction, always occur simultaneously.
Oxidation
Reduction
Reactant loses electrons
Reactant gains electrons
Oxygen Added
Oxygen Removed

22. Redox Examples
Corrosion is a redox reaction between a metal and oxygen (O2).
Combustion is a redox reaction between a non-metal and oxygen (O2).

23. Redox Examples
Corrosion is a redox reaction between a metal and oxygen (O2).
Combustion is a redox reaction between a non-metal and oxygen (O2).

24. Practice
These Practice Problems are presented in class

25. How do batteries and fuel cells work?
Batteries have 2 diodes; one that is oxidized and one that is reduced.
Acidic solution reacts with metals
Reactions free electrons
Battery
Anode
Cathode
Oxidation
Reduction
Metal loses e−
Metal gains e−
Negative (−)
Positive (+)

26. These Practice Problems are presented in class
A fuel cell uses a membrane to separate the reactants.
Hydrogen gas is oxidized.
Oxygen gas is reduced.
Product is pure water vapor.

27. Practice: Where do you store your batteries? Why?
A fuel cell uses a membrane to separate the reactants.
Hydrogen gas is oxidized.
Oxygen gas is reduced.
Product is pure water vapor.

28. Example: Al2O3 + Energy  Al2 + O2
What is electrolysis?
Electrolysis is the use of electric current to cause chemical change.
Reverses chemical reactions
Splits compounds
Example: Al2O3 + Energy  Al2 + O2
Question: How do you recharge your cell phone battery?

29. Example: Al2O3 + Energy  Al2 + O2
What is electrolysis?
Electrolysis is the use of electric current to cause chemical change.
Reverses chemical reactions
Splits compounds
Example: Al2O3 + Energy  Al2 + O2
Question: How do you recharge your cell phone battery?