Classifying Chemical
Reactions
And
Predicting Products
Classifying Chemical Reactions
1. Define a give general equations for synthesis, decomposition, single replacement, and double replacement, and combustion reactions.
2. Classify a reaction as synthesis, decomposition, single replacement, or double replacement, or combustion.
3. List three types of synthesis reactions.
4. List six types of decomposition reactions.
5. List four types of single replacement reactions.
6. List three types of double replacement reactions.
7. Predict the products of simple reactions given the reactants.
Five Basic Reaction Types
Five Main Classifications
of Chemical Reactions
Synthesis or Combination Reactions
Decomposition Reactions
Single Displacement/Replacement Rxns
Double Displacement/Replacement Rxns
Combustion Reactions
#1 Synthesis or Combination Reactions
• Two or more simpler substances combine to form a more complex substance.
element + element compound
A + X AX
• A and X can be elements or compounds
• AX is the new compound
HCl + NH3 NH4Cl
Synthesis
#2 Decomposition Reactions
A single compound undergoes a reaction that produces two or more simpler substances.
Some form of energy must be supplied compound element + element AX A + X
AX is the compound A and X are the simpler substances
2 H2O 2 H2 + O2
Decompostion
#3 Single Displacement /
Replacement Reactions • An active metal (A) displaces / replaces a less
active metal ion or hydrogen (B) in a compound.
A + BX AX + B
Hydrogen (metal want-a-be) can replace a few metals
• An active non-metal (Y) displaces / replaces a less active non-metal ion (X) in a compound.
Y + BX BY + X
Single Displacement /
Replacement Reactions
• One element displaces and replaces a similar element in a compound.
• See the Activity Series of elements.
It is the reverse order of the Reduction
Potentials in your data sheets.
Mg + 2 HCl MgCl2 + H2
Single Replacement
Single Replacement
#4 Double Displacement /
Replacement Reactions
When the ions of two compounds in an aqueous solution exchange places or switch partners to form two new compounds.
AX + BY AY + BX
A, X, B, Y represent the ions
AY and BX represent the two new compounds
Pb(NO3)2 (aq) + KI (aq) PbI2 (s) + 2 KNO3 (aq)
Double Replacement
#5 Combustion Reactions
The burning of natural gas, propane,
butane, gasoline, and wood represent
combustion reactions.
The combustible substance reacts with
oxygen to produce carbon dioxide and
water.
CH4 + 2 O
2 CO
2 + 2 H
2O
1. Decomposition Reactions
Heating oxyacids produce water and a
non-metal oxide.
H2SO4 heat H2O + SO3
2. Decomposition Reactions
• Heating metallic hydroxides produce a metal
oxide and water.
Ca(OH)2 heat CaO + H2O
3. Decomposition Reactions
Heating metal carbonates produces metal oxides and carbon dioxide.
Na2CO3 heat Na2O + CO2
Combustion of Propane & Ethanol
Propane Example:
C3H8 (g) + 5 O2 (g) 3 CO2 (g) + 4 H2O (g)
Ethanol Example:
C2H5OH(l) + 3 O2 (g) 2 CO2 (g) + 3 H2O (g)
Time to Practice
Identify the Category that the
Equations below belong to.
Identify the Category
Identify the Category
Identify the Category
Identify the Category
Identify the Category
What do these three reactions have
in common?
How are these three reactions
alike?
The End