1. Chemistry
Chapter 2 - Section 1
Chemical
Formulas &
Equations

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2. Physical or Chemical?
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3. Physical or Chemical?
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4. Physical or Chemical?
Yeast
+
Hydrogen Peroxide
=
???????
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5. Chemical Reaction?
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6. Chemical Reaction?
A process that
produces a
chemical change
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7. Chemical Equations
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8. Chemical Equations
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9. Chemical Equations
Substances that
exist before the
reaction begins
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10. Chemical Equations
Substances that Substances that
exist before the form as a result
reaction begins of the reaction
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11. Describe What is Happening
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12. Describe What is Happening
I use a
chemical
equation to
know the
reactants,
products and
proportions
of each
substance.
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13. Describe What is Happening
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14. Describe What is Happening
My Chemical
Equation can use
words,
chemical names,
or formulas.
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15. Using Words
Baking Soda + Vinegar -->
Gas + White Solid
Charcoal + Oxygen -->
Ash + Gas + Heat
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16. Chemical Names
Acidic Acid + Sodium Hydrogen Carbonate -->
Sodium Acetate + Water + Carbon Dioxide
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17. Chemical Formula’s
CH3COOH + NaHCO3 --> CH3COONa + H2O + CO2
Acetic Sodium Sodium Water Carbon
Acid Hydrogen Acetate Dioxide
Carbonate
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18. Arrows and Subscript
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19. It’s All a Balancing Act
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20. Conserve That Mass
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21. Conserve That Mass
The mass of the products must be
the same as the mass of the
reactants in the chemical reaction.
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22. Conserve That Mass
The mass of the products must be
the same as the mass of the
reactants in the chemical reaction.
Atoms are never lost of created in
a chemical reaction; however they
do change partners.
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23. Conserve That Mass
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24. Let’s Try
Tarnishing silver....
Ag + H2S --> Ag2S + H2
Hydrogen Silver
Silver sulfide Hydrogen
Sulfide
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25. Let’s Try
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26. Let’s Try
Na + AlCl3 --> NaCl + Al
KBr + Cl2 --> KCl + Br2
H2O2 --> H20 + O2
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27. Energy in a Chemical
Equation
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28. Energy in a Chemical
Equation
Energy is often released or absorbed
during a chemical reaction.
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29. Energy Released
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30. Energy Released
 Where does this energy come from?
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31. Energy Released
 Where does this energy come from?
 You have to think about the chemical
bonds of the reactants and the
products, in order to answer this
question.
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32. Energy Released
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33. Energy Released
 When energy is released, the products
are more stable, and their bonds have
less energy than those of the
reactants.
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34. Energy Released
 When energy is released, the products
are more stable, and their bonds have
less energy than those of the
reactants.
 The extra energy is released in
different forms: light, sound, thermal
energy.
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35. Energy Absorbed
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36. Energy Absorbed
 When energy is absorbed, the
reactants are more stable, and their
bonds have less energy than those
of the products.
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37. Energy Absorbed
 When energy is absorbed, the
reactants are more stable, and their
bonds have less energy than those
of the products.
 The extra energy needed to form
the products can be supplied in the
form of electricity, light, sound,
thermal energy.
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38. Energy Released
2H2 + O2 --> 2H2O + energy
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39. Energy Released
2H2 + O2 --> 2H2O + energy
2H2O + energy --> 2H2 + O2
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40. Energy Released
2H2 + O2 --> 2H2O + energy
Energy Absorbed
2H2O + energy --> 2H2 + O2
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41. When thermal energy is
gained or lost, special
terms are used….
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42. When thermal energy is
gained or lost, special
terms are used….
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43. When thermal energy is
gained or lost, special
terms are used….
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44. When thermal energy is
gained or lost, special
terms are used….
Absorb Release
thermal thermal
energy energy
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45. Endothermic or Exothermic
Absorb or Release
Quickly or Slowly
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46. Adding ENERGY to the
equation
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47. Finished!
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