Types of Chemical Reactions

Combination Reaction(also called Synthesis)

• Starts with:

– Two or more elements or compounds

• Ends with:

– One compound

• Example:

Mg + O2 MgO

2Mg + O2 2MgO

Decomposition Reaction• Starts with:

– One compound

• Ends with:

– Two or more elements or compounds

• Example:

CuCO3 CuO + CO2

Single-Replacement Reaction• Starts with:

– One element and one compound

• Ends with:

– One element and one compound

• Example:

Mg + HCl MgCl2 + H2

Mg + 2HCl MgCl2 + H2

Double-Replacement Reaction• Starts with:

– Two compounds

• Ends with:

– Two different compounds

• Example:

KI + Pb(NO3)2 PbI2 + KNO3

2KI + Pb(NO3)2 PbI2 + 2KNO3

Combustion Reaction• Starts with:

– Oxygen and a compound of C, H (and sometimes O).

• Ends with:

– Almost always CO2 and H2O

• Example:

CH4 + O2 CO2 + H2O

CH4 + 2O2 CO2 + 2H2O

Reaction Relationships• Combination

– Two people form a couple

• Decomposition– A couple breaks up

• Single Replacement– Love Triangle: One person breaks up a

couple and forms a new couple.

• Double Replacement– Two couples break up and form two new

couples