1. Chemical Reactions
Chapter 11
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2. Identifying Chemical Reactions!
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3. What are some indications that a chemical reaction has occurred?
Do Now!
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4. reactants  products Chemical Reactions
The process by which atoms of the same or different element rearrange themselves to form a new substance
Bonds are broken between atoms and re-formed to form new molecules
reactants  products
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5. How do we know a chemical reaction has occurred?
Production of heat
Absorption of heat (gets cold)
Production of gas (bubbles)
Production of a precipitate (solid)
Change in color
Change in odor
Change in state of matter
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6. 5 Types of Chemical Reaction
Synthesis
Decomposition
Single-Replacement
Double-Replacement
Combustion
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7. 1. Synthesis Also known as combination
When two or more substances react to form a SINGLE substance
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8. Synthesis
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9. 2. Decomposition
When a single substance breaks down into two or more products
Opposite of synthesis
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10. Decomposition
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11. 3. Single Replacement
Where one element replaces another element in a compound
Essentially one element switches compounds
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12. Single Replacment
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13. 4. Double Replacement
When there is an exchange of POSITIVE IONS between two compounds
The cations exchange places
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14. Double Replacement
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15. 5. Combustion
Where an element or compound reacts with oxygen to produce carbon dioxide and water
Produces heat and light
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16. Combustion
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17. Practice! Identify the following reactions
P4 + 3O2  2P2O3
Synthesis!
2MgI2 + Mn(SO3)2  2MgSO3 + MnI4
Double Displacement!
C6H12 + 9O2  6CO2 + 6H2O
Combustion!
2AgNO3 + Cu  Cu(NO3)2 + 2Ag
Single Displacement!
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18. Practice! Identify the following reactions
Pb + FeSO4  PbSO4 + Fe
P O2  2 P2O3
C6H O2  6 CO2 + 6 H2O
O3  O. + O2
2 AgNO3 + Cu  Cu(NO3)2 + 2 Ag
2 MgI2 + Mn(SO3)2  2 MgSO3 + MnI4
2 NO2  2 O2 + N2
SeCl6 + O2  SeO2 + 3Cl2
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19. Balancing Chemical Equations!
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20. Why must we balance chemical equations?
Law of Conservation of Mass
Matter cannot be created nor destroyed
Just like with math, both sides of the YIELDS sign must be equal!
So the same number of atoms must be on both sides of the equation
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21. Only Change the Coefficient!
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22. Methods of Balancing Equations
Inspection
“ABC” Method
Combustion Trick
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23. Inspection Use when it is easy to see the solution
List all the elements within the chemical equation
Count the number of elements on each side
Balance the coefficients and charges
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24. Inspection
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25. “ABC” Method Algebraically solve for the coefficients
Assign a letter for each coefficient in the reaction
Determine an algebraic equation to solve for the value of each coefficient
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26. “ABC” Method
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27. “ABC” Method
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28. “ABC” Method
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29. Combustion Trick Use only with combustion reactions!
Balance the carbon and hydrogen first using the inspection method
Balance the number of oxygens last
In the reactants, oxygen will always be alone as O2
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30. Combustion Trick 2 2 4 4 4
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31. Do Now! Balance the Following Equations
Li + H2O → LiOH + H2
K + B2O3 → K2O + B
C6H6 + O2 → CO2 + H2O
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32. The Law of Conservation of Mass
Matter can be changed from one form to another
Cannot be created or destroyed!
Why must we balance equations?
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