1. Chemical Equations and Reactions
By: Erica, Brittany, Dana

2. 5 Types of Chemical Reactions
There are 5 different types of reactions:
Synthesis
Decomposition
Single replacement
Double replacement
Combustion
They are used to predict the products of specific reactions

3. Synthesis
Two or more elements or compounds combine to make one compound
A+B AB
Example:
2Mg+O₂
Combine elements Mg and O to make one compound
2Mg+O₂2MgO

4. Practice Synthesis
Synthesis
C+O₂
S₈+8O₂

5. Practice Synthesis
Synthesis
C+O₂CO₂
S₈+8O₂8SO₂

6. Decomposition
A compound is broken down into 2 or more elements or compounds
ABA+B
Examples:
2H₂O
Break down the compound 2H₂O
2H₂O2H₂+O₂

7. Practice Decomposition
2HgO
CaCO₃

8. Practice Decomposition
2HgO2Hg+O₂
CaCO₃Ca+CO₂

9. Single Replacement
One part of a compound switches places with an element, forming a new compound
A+BCAC+B
Examples:
Fe+CuSO₄
Switch compounds Fe and Cu
Fe+CuSO₄Cu+FeSO₄

10. Practice single replacement
2Na+2H₂0
Mg+2HCl

11. Practice single replacement
2Na+2H₂02NaOH+H₂
Mg+2HClH₂+MgCl₂

12. Double Replacement
Parts of 2 compounds switch places to form 2 new compounds
AB+CDAD+CB
Examples:
2KI+Pb(NO₃)₂
Elements K and Pb Switch places
2KI+Pb(NO₃)₂2KNO₃+PbI₂

13. Practice Double Replacement
FeS+2HCl
HCl+NaOH

14. Practice Double Replacement
FeS+2HClH₂S+FeCl₂
HCl+NaOHNaCl+H₂O

15. Combustion
Any hydrocarbon burned in oxygen to form carbon dioxide and water
Examples of combustion are burning of natural gas, propane, gas, and wood
Example:
CH₄+O₂ CO₂+H₂O
Methane is burned in oxygen and creates carbon dioxide and water

16. Practice Combustion
Combustion
2H₂+O₂
C₃H₈+5O₂

17. Practice Combustion
Combustion
2H₂+O₂2H₂O
C₃H₈+5O₂3CO₂+4H₂O

18. Activity Series
A list of elements used to help predict whether or not a reaction will occur
The elements are organized according to the ease with which the elements undergo certain chemical reactions
In a single replacement reaction, an element can replace any element lower than it on the series

19. How about Zn + CaCl₂  ? How about Cu+ AgNO3  ?
Will this reaction occur?
Zn + HCl  ?
How about
Zn + CaCl₂  ?
How about
Cu+ AgNO3  ?

20. How about Zn + CaCl₂  ? How about Cu+ AgNO3  ?
Will this reaction occur?
Zn + HCl  ?
Yes, Hydrogen is lower than Zinc on the activity series. Therefore, Zinc will combine with Chlorine, and Hydrogen will separate from Zinc.
Zn + 2HCl  ZnCl₂ + H₂
How about
Zn + CaCl₂  ?
How about
Cu+ AgNO3  ?

21. How about Zn + CaCl₂  ? How about Cu+ AgNO3  ?
Will this reaction occur?
Zn + HCl  ?
Yes, Hydrogen is lower than Zinc on the activity series. Therefore, Zinc will combine with Chlorine, and Hydrogen will separate from Zinc.
Zn + 2HCl  ZnCl₂ + H₂
How about
Zn + CaCl₂  ?
Will not occur
How about
Cu+ AgNO3  ?
Will occur

22. Balancing Equations
Equations should be balanced because the Law of Conservation of Matter states that mass can not be lost or gained in a chemical reaction.
Therefore, the total mass of the reactants must equal total mass of the products

23. Balancing Decomposition of H₂O
Water  hydrogen + oxygen
H₂O  H₂ + O₂
because hydrogen and oxygen exist as diatomic molecules
There are two H molecules and one O molecule in the reactants
There are two H molecules and two O molecules in the products
This is not balanced

24. Balancing Decomposition of H₂O
H₂O  H₂ + O₂
2 H₂O  H₂ + O₂
Now there are more H molecules on the reactant side
2 H₂O  2 H₂ + O₂
Now there are 4 H molecules on each side and 2 O molecules on each side
Now it’s balanced! 

25. Writing and Balancing Practice
methane + oxygen  carbon dioxide + water
CH₄+ O₂  CO₂+ H₂O
CH₄+ 2 O₂  CO₂+ 2 H₂O
Try this!
Zinc + hydrochloric acid  zinc chloride + hydrogen
Zn + HCl  ZnCl₂ + H₂
Zn + 2 HCl  ZnCl₂ + H₂

26. Writing and Balancing Practice
Try this!
Iron sulfide + hydrochloric acid
Yield
Hydrogen sulfide + iron (III) chloride
FeS+HCl  H₂S + FeCl₂
FeS+2 HCl  H₂S + FeCl₂

27. Sources
solu_act.htm (activity series)