There are 5 major types of reactions that you might encounter.

1. Combination

2. Decomposition

3. Combustion

4. Single Replacement

5. Double Displacement

TYPE 1: Combination (also refered to as “Synthesis”)

• “Model” = A + B —> AB

• Example:

TYPE 2: Decomposition

TYPE 3: Combustion

TYPE 4:

Synthesis:     A + B → AB

1. Metal + nonmetal → binary salt

Example:  Na + Cl2 -> NaCl

1. Soluble metal oxide + water → metal hydroxide (base)

Example:   CaO + H2O → Ca(OH)2

1. Metal oxide + carbon dioxide → metal carbonate (opposite of decomp)

Example: Calcium oxide (CaO) + carbon dioxide (CO2) → calcium carbonate (CaCO3)

1. Metal oxide + sulfur dioxide → metal sulfite (opposite of decomp)

Example: 2CuO + 2SO2 → 2CuSO3

Decomposition:    AB → A + B

1. Binary compound → 2 elements

Example: 2 NaCl (s) → 2 Na (s) + Cl2 (g)

1. Metal carbonates → metal oxides and carbon dioxide

Example: 

1. Metal chlorates → metal chlorides and oxygen

Example: 

Specific Common Decomposition Reactions:

• Sulfurous acid → sulfur dioxide and water    

  1. Carbonic acid → carbon dioxide and water    

  2. Hydrogen peroxide → water and oxygen   

  3. **Ammonium hydroxide → ammonia and water   

**decompositions that can occur during a double displacement reaction

Single displacement:   A + BC → AC + B   or   A + BC → BA + C

1. Metals replace other metals

Example:  

1. Nonmetals replace other nonmetals

Example:  

1. Alkali metals + water → metal hydroxide and hydrogen

Example:  

Double displacement:   AB + CD → AD + CB

1. Use solubility rules to predict precipitates

Example:  

1. **If a product is sulfurous acid, carbonic acid or ammonium hydroxide,  the decomposition reaction will also happen (double displacement & decomposition)

Example:  CaCO3 + 2HCl → CaCl2 + H2O + CO2

In this reaction, the calcium carbonate and hydrochloric acid exchange ions to form calcium chloride, water, and carbon dioxide. Carbonic acid (H2CO3) is formed as an intermediate product when carbon dioxide dissolves in water.

Combustion:   X + O2 → CO2 + H2O

1. A hydrocarbon + oxygen → carbon dioxide and water

Example: