Chemical Reaction Types
Adapted from www.chemistrygeek.com
Predicting Whether a Reaction
Will Occur

What makes reactants “want” to form
products?




Formation of a solid
Formation of water
Transfer of electrons
Formation of a gas
Types of Reactions
1.
2.
3.
4.
5.
6.
7.
Synthesis/Combination
Decomposition
Single Replacement
Double Replacement (Precipitation)
Combustion
Acid/Base (WH)
Oxidation-Reduction (Redox)(WH)
Steps to Writing Reactions
•
General steps for writing reactions
1.
2.
3.
Identify the type of reaction
Predict the product(s) using the type of
reaction as a model
Balance it
Don’t forget about the diatomic elements!
(BrINClHOF) For example, Oxygen is O2 as an
element.
In a compound, it can’t be a diatomic element
because it’s not an element anymore, it’s a
compound!
Synthesis/Combination
•
Two substances (generally elements)
combine and form a compound
•
•
reactant + reactant  1 product
Basically: A + B  AB
•
•
Example: 2H2 + O2  2H2O
Example: C + O2  CO2
Synthesis Reactions
https://www.youtube.com/watchv=ewIA0N8wX18
Learning Check
•
•
•
•
Predict the products. Write and balance
the following synthesis reaction equations.
Sodium metal reacts with chlorine gas
Na(s) + Cl2(g) 
Solid Magnesium reacts with fluorine gas
Mg(s) + F2(g) 
Aluminum metal reacts with fluorine gas
Al(s) + F2(g) 
Decomposition Reactions
•
•
•
•
•
•
A single compound breaks down into elements
or into simpler compounds
Often require a catalyst (Heat/light)
1 Reactant  Product + Product
In general: AB  A + B
Example: 2 H2O  2H2 + O2
Example: 2 HgO  2Hg + O2
Decomposition Reactions
https://www.youtube.com/watch?v=0y9NOyTgJ88
Decomposition Exceptions
•
Carbonates and chlorates are special case
decomposition reactions that do not go to
the elements.
•
Carbonates (CO32-) decompose to carbon
dioxide and a metal oxide
•
•
Example: CaCO3  CO2 + CaO
Chlorates (ClO3-) decompose to oxygen gas
and a metal chloride
•
Example: 2 Al(ClO3)3  2 AlCl3 + 9 O2
Learning Check
•
•
•
Predict the products. Then, write and
balance the following decomposition
reaction equations:
Solid Lead (IV) oxide decomposes
PbO2(s) 
Aluminum nitride decomposes
AlN(s) 
Learning Check
Identify each as synthesis or decomposition
reactions, and write the balanced equation:
N2(g) + O2(g)  (nitrogen monoxide)
BaCO3(s) 
Co(s)+ S(s)  (make Co+3)
NH3(g) + H2CO3(aq) 
NI3(s) 
Single Replacement Reactions
•
•
•
Single Replacement Reactions occur when
one element replaces another in a compound.
A metal can replace a metal (+) OR
a nonmetal can replace a nonmetal (-).
element + compound element + compound
A + BC  AC + B (if A is a metal) OR
A + BC  BA + C (if A is a nonmetal)
(remember the cation always goes first!)
When H2O splits into ions, it splits into
H+ and OH- (not H+ and O-2 !!)
Single Replacement Reactions
https://www.youtube.com/watch?v=fJwkxD_wZvk
Activity Series of Metals and Nonmetals
•Use the Activity Series to
predict whether or not a
Single Replacement reaction
will occur
•In general, the single
metal/halogen must be
HIGHER on the list than the
metal/halogen in the
compound
Activity Series of Metals and Nonmetals



Which reaction will occur spontaneously?
Pb(s)
(aq)
+
MgSO4 (aq)
Mg(s) +
PbSO4
Mg(s)
(aq)
+
PbSO4 (aq) 
Pb(s) +
MgSO4
Learning Check
•
•
•
•
•
•
Decide whether the following single replacement
reactions will occur. If so, predict the products and
balance the equation
Zn(s) + HCl(aq) 
NaCl(s) + F2(g) 
Al(s)+ Cu(NO3)2(aq)
Ca(s) + KNO3(aq) 
KBr(aq) + I2(s) 
4. Double Replacement Reactions
•
Double Replacement Reactions occur
when a metal replaces a metal in a compound
and a nonmetal replaces a nonmetal in a
compound
Compound + compound  compound+
compound
AB + CD  AD + CB
•
https://www.youtube.com/watch?v=2EQznGPZY5A
•
•
Double Replacement Reactions
•
•
•
Think about it like “foil”ing in algebra, first and
last ions go together + inside ions go together
Example:
AgNO3(aq) + NaCl(s)  AgCl(s) + NaNO3(aq)
Another example:
K2SO4(aq) + Ba(NO3)2(aq)  2 KNO3(aq) + BaSO4(s)
Solubility Rules




Use the solubility rules chart to predict
whether a reaction will occur
A formation of one precipitate (solid)
indicates a reaction
If two soluble (aqueous) compounds form,
then there is no visible reaction
Most of the rules are written in terms of
anions, so look at the anion first!
Solubility Rules
Rule #
If the compound contains…
Aqueous or Solid?
1
•Any Group 1A cation (H+, Li+ Na+, K+) Always aqueous
•Ammonium (NH4+)
2
•Acetate (C2H3O2-)
•Chlorate (ClO3-)
•Nitrate (NO3-)
Always aqueous
3
•Sulfate (SO4-2)
Aqueous
UNLESS paired with
Pb+2, Hg+2, Ag+, Ba+2, Sr+2,
or Ca+2
4
•Halides
(F-, Cl-, Br-, I-)
Aqueous
UNLESS paired with
Pb+2, Hg+2, Ag+
5
•Carbonate (CO3-2)
•Phosphate (PO4-3)
•Chromate (CrO4-2)
•Sulfide (S-2)
•Hydroxide (OH-)
Solid
UNLESS paired with any
cation from Rule #1
Learning Check

Predict if the following compounds will be
Aqueous or Solid








CaCO3
NaCl
PbSO4
BaCl2
KNO3
AgPO4
MgC2H3O2
FeS
Learning Check
1. Decide if the following reactions will produce a
solid precipitate.
2. Predict the products and balance the equations
a. HCl(aq) + AgNO3(aq) 
b. CaCl2(aq) + Na3PO4(aq) 
c. Pb(NO3)2(aq) + BaCl2(aq) 
d. FeCl3(aq) + NaOH(aq) 
e. H2SO4(aq) + NaOH(aq) 
f. KOH(aq) + CuSO4(aq) 
5. Combustion Reactions
(Burning)
•
•
•
Combustion reactions
occur when a hydrocarbon
(CxHy) reacts with oxygen
gas
Carbon Dioxide, Water and
Heat are produced
The “Fire Triangle”
1) A Fuel (hydrocarbon)
2) Oxygen
3) Ignition Source (spark)
Combustion Reactions
•
•
•
•
In general:
CxHy + O2  CO2 + H2O
Combustion is used to heat
homes and run automobiles
(octane, as in gasoline, is C8H18)
Incomplete burning can also
result in the production of
carbon monoxide (CO)
https://www.youtube.com/watch?v=
oRngPHRj0vA
Learning Check
•
Example
•
•
C5H12 + 8 O2  5 CO2 + 6 H2O
Write the products and balance the
following combustion reactions:
•
•
C10H22 + O2 
CH4 +
O2 
Learning Check - Mixed Practice
1.
State the type, predict the products, and
balance the following reactions:
BaCl2 + H2SO4 
2.
C6H12 + O2 
3.
Zn + CuSO4 
4.
Cs + Br2 
5.
FeCO3 
•
Acid/Base Reactions (WH)

Acid – substance that donates H+ ions

HCl
+
H2O 
H3O+(aq)
+
Cl-(aq)
hydronium ion

Base – substance that accepts H+ ions

NH3
+
H2O 
ion


NH4+(aq)
+
OH-(aq)
hydroxide
Strengths of acids and bases are determined
by how much H+ they can donate or accept
in solution
We will only focus on strong acids and bases
Acid/Base Reactions (WH)


A strong acid and a strong base will react to form
water and a salt (ionic compound)
HCl (aq) +
NaOH(aq) 
H2O +
NaCl(aq)
Learning Check (WH)
Write out the following acid/base reactions
1. Aqueous nitric acid reacts with aqueous
potassium hydroxide

2. Aqueous sulfuric acid reacts with aqueous
calcium hydroxide
Oxidation-Reduction Reactions
(WH)


Any reaction that involves a transfer of
electrons
Metal reacts with Non-metal (ionic compound)


2Na(s) +
0
Cl2(g) 
0
2NaCl(s)
+ -
Two non-metals react (O2 reactant/product)

CH4(g) +
2O2(g) 
CO2(g)+
2H2O(g)
Learning Check (WH)

For each of the following reactions, show
how electrons are gained and lost
2Al(s) +
3I2(s)  2AlI3(s)

2Cs(s) +

F2(g) 
2CsF(s)
Exothermic and Endothermic
Reactions


Reactions will either absorb or release
energy as they progress
Exothermic Reactions



release energy (heat is a product)
Temperature of system increases
Endothermic Reactions


absorb energy (heat is a reactant)
Temperature of system decreases
Exothermic and Endothermic
Reactions


Exothermic – Combustion Reaction

CH4
+
O2

Heat is written as a product

CO2 +
H2O + heat
Endothermic –Baking Soda and Vinegar Reaction
 NaHCO3
+ HC2H3O2 +
heat 
CO2 +
H2O +
NaC2H3O2
 Heat is written as a reactant
Reactions in Aqueous Solution (WH)

Molecular equations – overall reactions

Full Ionic Equation – represents all AQUEOUS
reactants ad products as ions



Any aqueous compound is split into ions
Any solid, liquid or gas is unchanged
Net Ionic Equation – includes only those
components that undergo a change


Spectator ions – ions that do not participate in the
reaction
Spectator ions remain as ions on both sides of the
equation and are eliminated
Full Ionic Equations (WH)
Molecular Equation:
K2CrO4 + Pb(NO3)2 
PbCrO4 + 2 KNO3
Aqueous
Solid
Aqueous
Aqueous
Full Ionic Equation:
2 K+ + CrO4 -2 + Pb+2 + 2 NO3- 
PbCrO4 (s) + 2 K+ + 2 NO3-
Net Ionic Equations (WH)
Using the Full ionic equations, cancel out
ions that appear on BOTH sides of the
equation
Total Ionic Equation:
2 K+ + CrO4 -2 + Pb+2 + 2 NO3- 
PbCrO4 (s) + 2 K+ + 2 NO3Net Ionic Equation:
CrO4 -2 + Pb+2  PbCrO4 (s)

Learning Check (WH)




Write the molecular, full ionic and net ionic equations
for the following reactions
Silver nitrate reacts with Lead (II) Chloride in hot
water.
Aqueous sodium sulfide is mixed with aqueous copper
(II) nitrate.
Zinc metal reacts with hydrochloric acid.