2. Five Types of Chemical Reactions
• Synthesis
• Decomposition
• Single Replacement
• Double Replacement
• Combustion
3. Synthesis
• The word synthesis means to put things together to make a whole.
• In a synthesis reaction, two or more substances combine to form a
single new substance.
• The general formula for a synthesis reaction is:
A + B AB
4. Synthesis
Synthesis reactions are easy to recognize. There will be two
or more reactants, but only one product. Below are some
examples of synthesis reactions.
2H2+ O2 2H2O
CO2 + H2O H2CO3
MgO + H2O Mg(OH)2
2Na + Cl2 2NaCl
5. Decomposition
• The word decomposition means to separate or breakdown into
smaller pieces.
• In a decomposition reaction, one substance breaks down into two or
more products. It is really a synthesis reaction in reverse.
• The general formula for a decomposition reaction is:
AB A + B
6. Decomposition
In order to identify decomposition reactions, look for chemical
equations which have only one reactant, but two or more
products. Below are some examples of synthesis reactions.
2NaHCO3 2CO2 + H2O + Na2O
CuCO3 CO2 + CuO
2H2O2 O2 + 2H2O
H2SO4 H2O + SO3
7. Single Replacement
• In a single replacement reaction, one element replaces another
element in a compound.
• The general formula for a single replacement reaction is:
A + BC B + AC
8. Single Replacement
Single replacement reactions have an element and a
compound on both the reactant and product side of the
equation. Below are some examples of synthesis reactions.
Fe + CuSO4 FeSO4 + Cu
2NaBr + Cl2 2NaCl + Br2
Mg + H2O MgO + H2
9. Double Replacement
• In a double replacement reaction, a compound reacts with another
compound to form two new compounds.
• The general formula for a single replacement reaction is:
AB + CD AD + BC
10. Double Replacement
Double replacement reactions have two compounds on both
the reactant and product side of the equation. Below are some
examples of synthesis reactions.
HCl + NaOH NaCl + H2O
KOH + H2SO4 K2SO4 + H2O
AgNO3 + NaCl AgCl + NaNO3
11. Combustion
• Combustion, or burning, is a chemical reaction between an organic
compound (usually a hydrocarbon) and oxygen gas.
• The products in a combustion reaction are carbon dioxide and
water.
• Combustion reactions are exothermic, meaning that they produce
heat.
• The general formula for a combustion reaction is:
CxHx + O2 CO2 + H2O
12. Combustion
Combustion reactions always have oxygen gas as a reactant
and water and carbon dioxide as products. Below are some
examples of combustion reactions.
CH4 + 2O2 CO2 + 2H2O
2C4H10 + 13O2 8CO2 + 10H2O
CH3OH + O2 CO2 + 2H2O
