1. II. Five basic types of chemical reactions:

2. A. Synthesis (composition):
two or more elements or compounds may combine to form a more complex compound.
Basic form: A  +  X   AX

3. Examples of synthesis reactions
Metal  +  oxygen  metal oxide
ex Mg  +  O2   2MgO

4. Nonmetal  +  oxygen  nonmetallic oxide
ex C  +   O2   CO2

5. Metal oxide  +  water   metallic hydroxide
ex MgO  +   H2O   Mg(OH)2

6. Nonmetallic oxide  +  water   acid
ex CO2  +  H2O    H2CO3

7. Metal + nonmetal   salt
ex Na  +  Cl2   2NaCl

8. A few nonmetals combine with each other.
ex P  +  3Cl2   2PCl3

9. What do all of these have in common?
2Mg  +  O2   2MgO
C  +   O2   CO2
CO2  +  H2O    H2CO3
MgO  +   H2O   Mg(OH)2
2 Na  +  Cl2   2NaCl
2P  +  3Cl2   2PCl3

10. Example Zinc + Iodine zinc iodide Oxygen + Hydrogen  Water
Click on pictures
Oxygen + Hydrogen  Water

11. Practice Predicting Products of Synthesis Reactions

12. B. Decomposition:
A single compound breaks down into its component parts or simpler compounds.
Basic form: AX  A  +  X

13. Examples of decomposition reactions:
Metallic carbonates, when heated, form metallic oxides and CO2 .
ex CaCO3   CaO  +  CO2

14. Most metallic hydroxides, when heated, decompose into metallic oxides and water.
ex Ca(OH)2   CaO  +  H2O

15. Metallic chlorates, when heated, decompose into metallic chlorides and oxygen.
ex KClO3   2KCl  +  3O2

16. Some acids, when heated, decompose into nonmetallic oxides and water.
ex H2SO4   H2O  +  SO3

17. Some oxides, when heated, decompose.
ex HgO   2Hg  +  O2

18. Some decomposition reactions are produced by electricity.
ex H2O   2H2  +  O2
ex NaCl   2Na  +  Cl2

19. What do all of these have in common?
CaCO3   CaO  +  CO2
Ca(OH)2   CaO  +  H2O
2KClO3   2KCl  +  3O2
H2SO4   H2O  +  SO3
2HgO   2Hg  +  O2
2H2O    2H2  +  O2

20. Example
Decomposition of ammonium dichromate

21. Practice Predicting Products of Decomposition Reactions

22. C. Single Replacement:
a more active element takes the place of another element in a compound and sets the less active one free.
Basic form: A  +  BX   AX  +  B
 or
AX  +  Y   AY + X

23. Examples of replacement reactions:
Replacement of a metal in a compound by a more active metal.
ex. Fe  +  CuSO4   FeSO4  +  Cu

24. Replacement of hydrogen in water by an active metal.
ex. 2Na  +  2H2O   2NaOH  +  H2
ex. Mg  +  H2O   MgO  +  H2

25. Replacement of hydrogen in acids by active metals.
ex. Zn  +  2HCl   ZnCl2  +  H2

26. Replacement of nonmetals by more active nonmetals.
ex. Cl2  +  2NaBr   2NaCl  +  Br2

27. Examples

28. D. Ionic or Double Replacement:
occurs between ions in aqueous solution.
A reaction will occur when a pair of ions come together to produce at least one of the following:
a precipitate
a gas
water or some other non-ionized substance.
Basic form: AX  + BY    AY  +  BX

29. Examples of ionic reactions:
Formation of precipitate.
ex. NaCl  +  AgNO3  NaNO3  +  AgCl
ex. BaCl2  +  Na2 SO4   2NaCl  +  BaSO4

30. Formation of a gas.
ex. HCl  +  FeS -  FeCl2  +  H2S

31. Formation of water. (If the reaction is between an acid and a base it is called a neutralization reaction.)
ex. HCl  +  NaOH   NaCl  +  H2O

32. Formation of a product which decomposes.
ex. CaCO3  +  HCl   CaCl2  +  CO2  +  H2O

33. Ammonium chloride + barium hydroxide
Example
Ammonium chloride + barium hydroxide

34. Practice Predicting Products of Ionic Reactions

35. Combustion of Hydrocarbons:
When a hydrocarbon is burned with sufficient oxygen supply, the products are always carbon dioxide and water vapor.
If the hydrocarbon has an even number of carbons, start with a coefficient of 2 CxHy
Balance in this order: C, H, O

36. If the supply of oxygen is low or restricted, then carbon monoxide will be produced.
This is why it is so dangerous to have an automobile engine running inside a closed garage or to use a charcoal grill indoors.

37. NOTE:
The phrase "To burn" means to add oxygen unless told otherwise.

38. (CxHy) + O2  CO2 + H2O ex. CH4 + 2O2  CO2 + 2H2O

39. Analyzing Chemical Reactions
One Reactant? no
yes
One Product?
Decomposition no
yes
Next slide
Synthesis

40. 2 Ionic Compounds or Acid and Ionic Compound?
yes no
Double Replacement
Next slide
Precipitate Neutralization Gas

41. yes no Element and Compound? Single Replacement Hydrocarbon and O2 no
Metal Halogen Metallic oxide no
Combustion
????

42. Precipitate Gas Neutralization
One Reactant?
yes no
One Product?
Decomposition
yes no
Synthesis
2 Ionic Compounds or Acid and Ionic Compound?
yes no
Double Replacement
Element and Compound?
yes no
Precipitate Gas Neutralization
Hydrocarbon and O2?
Single Replacement
yes no no
Combustion
????