1. Unit 3: Chemical Equations and Stoichiometry
Types of Reactions

2. Synthesis/Combination Reactions
In a synthesis reaction, two or more substances combine to form a new compound.
A + B → AB
How do you tell?
More reactants than products

3. Decomposition Reaction
In a decomposition reaction a single compound is broken down to form two or more smaller compounds.
AB → A + B
How do you tell?
More products than reactants

4. Single Displacement Reaction
In a single displacement reaction, one element replaces a similar element in a compound.
A + BX → AX + B
How do you tell?
element + compound → element + compound

5. Double Displacement Reaction
In a double displacement reaction, ions from two compounds in solution exchange places to produce two new compounds.
AB + CD → AD + CB
NaCl + AgNO3  AgCl + NaNO3
How do you tell?
compound + compound → compound + compound

6. Types of Reactions Practice
Identify the following unbalanced reactions as synthesis, decomposition, single displacement, or double displacement. EXPLAIN YOUR CHOICE.
1. KOH + HBr → KBr + H2O
2. Mg + CO2 → MgO + C
3. PCl3 + Cl2 → PCl5

7. Combustion Reaction Carbon compound + O2 → CO2 + H2O
In a combustion reaction (burning), a carbon compound combines with oxygen and releases a large amount of energy in the form of light and heat.
Carbon compound + O2 → CO2 + H2O
The products of a combustion reaction are ALWAYS CO2 + H2O

9. Carbon compound + O2 → CO2 + H2O
Type of Reaction
Identifying the type…
General Equation
two or more reactants combine to produce ONE compound
A + B → AB
Synthesis →
ONE compound is broken down to produce two or more compounds
AB → A + B
Decomposition →
element + compound produces element + compound
A + BX → AX + B
Single Displacement →
two compounds produce two compounds
AB + CD → AD + BC
Double Displacement →
burning - carbon compound combines with oxygen to release heat/energy
Carbon compound + O2 → CO2 + H2O
Combustion
ALWAYS THE PRODUCTS!

10. Types of Reaction Examples
Synthesis:
Mg + O2  MgO
Decomposition:
KBrO3  KBr + O2
Single Displacement:
Fe + CuSO4  Cu + FeSO4
Double Displacement:
NaCl + AgNO3  AgCl + NaNO3
Combustion:
C6H14 + O2 → CO2 + H2O