1. Chemical Reactions

2. 5 Types of Chemical Reactions
Synthesis
Decomposition
Single Replacement
Double Replacement
Combustion

3. Synthesis A + B  AB 4Fe + 3O2  2Fe2O3
Two or more reactants combine to form a single product. (Only 1 product forms)
A + B  AB
4Fe + 3O2  2Fe2O3

4. Decomposition AB  A + B 2H2O  2H2 + O2
A single reactant forms two or more products. (Only 1 reactant)
AB  A + B
2H2O  2H2 + O2

5. Single Replacement “Cutting In”
One element takes the place of another element in a compound. A + BC  AC+ B
metal replaces metal (+), nonmetal replaces nonmetal (-)
Fe + CuSO4 FeSO4 + Cu
Cl2 + 2NaBr  2NaCl + Br2

6. Double Replacement “Switching Partners”
Ions of two compounds switch places. AB + CD  AD + CB Pb(NO3)2 + 2KI  PbI2 + 2KNO3

7. Combustion Reaction Uses oxygen (O2) as a reactant. Produced Heat.
The products usually include
CO2 and H2O
CH3OH + O2  CO2 + H2O

8. Check for Understanding
What do you look for in a synthesis reaction?
Answer: Two or more reactants and one product.
What do you look for in a decomposition reaction?
Answer: One reactant and two or more products.
4/26/2019

9. Check for Understanding
What do you look for in a combustion reaction?
Answer: Two products: CO2 and H2O.
What do you look for in a single replacement reaction?
Answer: One element takes the place of another element in a compound.
4/26/2019

10. Check for Understanding
What do you look for in a double replacement reaction?
Answer: Two ionic compounds exchange ions to form two new ionic compounds.
4/26/2019

11. Check for Understanding
Classify each reaction:
2C6H6 + 15O2  12CO2 + 6H2O
Answer: Combustion
N2 + 3H2  2NH3
Answer: Synthesis
F2 + MgCl2  MgF2 + Cl2
Answer: Single Displacement
(NH4)2Cr2O7  N2 + 4H2O + Cr2O3
Answer: Decomposition
KCl + AgNO3  AgCl + KNO3
Answer: Double Displacement
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12. Review

13. 4 Indicators of Chemical Reactions
How do you know a chemical reaction when you see one?
A Gas is Created (NOT a phase change)
Release/Absorption of Energy (heat or light)
Extreme Color Change
Formation of a Precipitate (solid)

14. Release/Absorption of Energy
Exothermic – energy is released
Feels HOT to the touch.
ex. Burning wood, fireworks exploding, Freezing
Endothermic – energy is absorbed
Feels COLD to the touch.
Ice packs, Melting

15. Balancing Equations
Law of Conservation of Mass: No atoms are created or destroyed in chemical reactions. Atoms are just rearranged.
Reactants  Products
#atoms of each element in the reactants = # atoms of each element in the products

16. Balancing Equations Rules:n
NEVER change the subscripts. Add coefficients to balance the number of atoms.
Save O and H for last.
If you have an odd number of an element (ex. oxygen) on one side, try putting a 2 (or another even coefficient).

17. Name the reaction type and Balance the equation
__ Ca3(PO4)2 + __ H2SO4  __ CaSO4 + __H3PO4
___KClO3  ___KCl + ___O2
___C2H2 + ___O2  ___CO2 + ___H2O
___C + ___H2O  ___CO + ___H2
___P4 + ___O2  ___P2O5

18. Name the reaction type and Balance the equation
__ Ca3(PO4)2 + __ H2SO4  __ CaSO4 + __H3PO4

19. Name the reaction type and Balance the equation
___KClO3  ___KCl + ___O2

20. Name the reaction type and Balance the equation
___C2H2 + ___O2  ___CO2 + ___H2O

21. Name the reaction type and Balance the equation
___C + ___H2O  ___CO + ___H2

22. Name the reaction type and Balance the equation
___P4 + ___O2  ___P2O5