2. Synthesis Reactions  In synthesis reactions, two elements or compounds combine to form one new compound. A + B  AB e.g. 2Na + Cl 2  2NaCl

3. Decomposition Reactions  In a decomposition reaction one compound breaks down into two or more elements or smaller compounds. AB  A + B E.g. 2NaN 3  2Na + 3N 2

4. Replacement Reactions  There are two types of replacement reactions: Single Replacement Double Replacement

5. Single Replacement Reactions  Single replacement reactions occur when one element replaces another element in a compound. A + BC  B + AC E.g. Cu + 2AgNO 3  2Ag + Cu(NO 3 ) 2

6. Double Replacement Reactions  Double replacement reactions occur when the elements of two compounds switch places. AB + CD  AD + BC E.g. Ca(OH) 2 + 2HCl  CaCl 2 + H 2 O  Double replacement reactions normally produce a gas, a solid, or water. When a solid is produced during a reaction, it is called a precipitate.

7. Combustion Reactions  In combustion reactions, a substance combines with oxygen and releases energy in the form of light or heat. Most combustion reactions produce CO 2 and H 2 O E.g. CH 4 + 2O 2  CO 2 + 2H 2 O Cellular respiration, and burning of fossil fuels (which powers cars) are examples of combustion reactions.

10. Synthesis MAKE SURE YOU CROSS THE CHARGES  KEY – They make ONE PRODUCT  Ca + O 2   Ca + O 2  CaO  2Ca + O 2  2CaO  K + Cl 2   K + Cl 2  KCl  2K + Cl 2  2KCl

11. Decomposition  KEY – 1 reactant to 2 or more products  H 2 O   H 2 O  H 2 + O 2  2H 2 O  2H 2 + O 2  HgO   HgO  Hg + O 2  2HgO  2Hg + O 2

12. Single-Replacement MAKE SURE YOU CROSS THE CHARGES  Mg + CuSO 4   Mg + CuSO 4  MgSO 4 + Cu  Al + CuCO 3   Al + CuCO 3  Al 2 (CO 3 ) 3 + Cu  2Al + 3CuCO 3  Al 2 (CO 3 ) 3 + 3Cu  Cl 2 + KI   Cl 2 + KI  KCl + I 2  Cl 2 + 2KI  2KCl + I 2

13. Examples of Double Replacement MAKE SURE YOU CROSS THE CHARGES  NaCl + AgNO 3   NaCl + AgNO 3  NaNO 3 + AgCl  AgClO 3 + ZnCl 2   AgClO 3 + ZnCl 2  AgCl + Zn(ClO 3 ) 2  2AgClO 3 + ZnCl 2  2AgCl + Zn(ClO 3 ) 2

14. Combustion KEY- If it is a hydrocarbon combining with Oxygen gas, you will always produce carbon dioxide and water. C 6 H 12 O 6 + O 2  C 6 H 12 O 6 + O 2  CO 2 + H 2 O C 6 H 12 O 6 + 6O 2  6CO 2 + 6H 2 O C 2 H 5 OH + O 2  C 2 H 5 OH + O 2  CO 2 + H 2 O C 2 H 5 OH + 3O 2  2CO 2 + 3H 2 O

15. Easy Reference  Synthesis – multiple reactants, 1 product  Decomposition – 1 reactant, multiple products  Single-Replacement – reactants & products have an element and a compound  Double-Replacement – reactants & products are made up of compounds  Combustion – CH’s plus O 2 yield CO 2 & H 2 O