Download Reaction Types PowerPoint

II. Five basic types of chemical
reactions:
B. Decomposition:
A single compound breaks down into its
component parts or simpler compounds.
Basic form:
AX  A + X
Examples of decomposition
reactions:
Metallic carbonates, when heated, form
metallic oxides and CO2 .
ex.
CaCO3  CaO + CO2
Most metallic hydroxides, when heated,
decompose into metallic oxides and water.
ex.
Ca(OH)2  CaO + H2O
Metallic chlorates, when heated, decompose
into metallic chlorides and oxygen.
ex.
2KClO3  2KCl + 3O2
Some acids, when heated, decompose into
nonmetallic oxides and water.
ex.
H2SO4  H2O + SO3
Some oxides, when heated, decompose.
ex.
2HgO  2Hg + O2
Some decomposition reactions are
produced by electricity.
ex.
2H2O
2H2 + O2
ex.
2NaCl
2Na + Cl2
What do all of these have in
common?
CaCO3  CaO + CO2
Ca(OH)2  CaO + H2O
2KClO3  2KCl + 3O2
H2SO4  H2O + SO3
2HgO  2Hg + O2
2H2O 
2H2 + O2
Example
Decomposition of ammonium dichromate
Practice Predicting Products of
Decomposition Reactions
D. Ionic or Double Replacement:
occurs between ions in aqueous solution.
A reaction will occur when a pair of ions come
together to produce at least one of the following:
1.
a precipitate
2.
a gas
3.
water or some other non-ionized substance.
Basic form:
AX + BY  AY + BX
Examples of ionic reactions:
#3: Formation of water. (If the reaction is
between an acid and a base it is called a
neutralization reaction.)
ex. HCl + NaOH  NaCl + H2O
#2 Formation of a gas.
ex.
HCl + FeS - FeCl2 + H2S
H2S is the only gas you need
to remember.
Look for one of these three.
Rewrite equation, replacing unstable compound with products.
Ex. NH4Cl + Ca(OH)2  NH4OH + CaCl2
NH4Cl + Ca(OH)2  NH3  +H2O + CaCl2
Now balance the equation! Note the up arrow. You must indicate that a gas is produced!
#1 Formation of precipitate.
(A solid that was not present in the reactants)
Marked with (s) or 
Use Solubility Table
S mean soluble, or dissolved. No
precipitate is formed.
ALL OTHER LETTERS MEAN THAT
A PRECIPITATE FORMS.
Look up the formulas for your
products.
Whichever forms a precipitate is
marked with (s) or  . Any soluble
products are marked (aq).
If no solid forms, write N.R. for
no reaction.
Magnesium acetate + sodium carbonate 
Think: It's not an acid + base.
What are the products?
magnesium carbonate and
sodium acetate
Any unstable product?
Look for H2CO3, H2SO3, NH4OH
Not there. Now check for a precipitate.
Magnesium carbonate has a P solid
forms.
Finish equation with a down arrow or (s)
after the magnesium carbonate.
Example
Ammonium chloride + barium
hydroxide
Practice Predicting Products of Ionic
Reactions
Combustion of Hydrocarbons:

Hydrocarbons contain hydrogen and
carbon. Some also have oxygen.

When a hydrocarbon is burned with
sufficient oxygen supply, the products are
always carbon dioxide and water vapor.

Balance in this order: C, H, O

If the supply of oxygen is low or restricted,
then carbon monoxide will be produced.
This is why it is so dangerous to have an
automobile engine running inside a closed
garage or to use a charcoal grill indoors.
NOTE:
The phrase "To burn" means to add
oxygen unless told otherwise.
(CxHy) + O2  CO2 + H2O
ex. CH4 + 2O2  CO2 + 2H2O
ex. 2C4H10
13O2  8CO2 + 10H2O
C. Single Replacement:
a more active element takes the place of another
element in a compound and sets the less active
one free.
Basic form: A + BX  AX + B
or
AX + Y  AY + X
Examples of replacement
reactions:
ex. Fe + CuSO4  FeSO4 + Cu
2. Replacement of hydrogen in water by an
active metal.
ex.
2Na + 2H2O  2NaOH + H2
Only one hydrogen is replaced, leaving
an hydroxide ion.
Only these metals
will react with water,
producing hydrogen gas
and metallic hydroxide.
3. Replacement of hydrogen in acids by
active metals.
ex. Zn + 2HCl  ZnCl2 + H2
Only these metals
will react with acids,
producing hydrogen gas
and metallic hydroxide.
ex.
Cl2 + 2NaBr  2NaCl + Br2
The halogen is replaced,
NOT the metal! The
halogen activity series
is Group 17 on the
Periodic Table.
Examples
A. Synthesis (composition):
two or more elements or compounds may
combine to form a more complex
compound.
Basic form:
A + X  AX
Examples of synthesis reactions
Metal + oxygen  metal oxide
ex.
2Mg + O2  2MgO
Nonmetal + oxygen  nonmetallic oxide
ex.
C + O2  CO2
Metal oxide + water  metallic hydroxide
ex.
MgO + H2O  Mg(OH)2
Nonmetallic oxide + water  acid
ex.
CO2 + H2O  H2CO3
Metal + nonmetal  salt
ex.
2 Na + Cl2  2NaCl
A few nonmetals combine with each
other.
ex.
2P + 3Cl2  2PCl3
What do all of these have in
common?
2Mg + O2  2MgO
C + O2  CO2
CO2 + H2O  H2CO3
MgO + H2O  Mg(OH)2
2 Na + Cl2  2NaCl
2P + 3Cl2  2PCl3
Example
Zinc + Iodine zinc iodide
Click on pictures
Oxygen + Hydrogen  Water
Practice Predicting Products of
Synthesis Reactions
Analyzing Chemical Reactions
One Reactant?
no
yes
Decomposition
One Product?
yes
Synthesis
no
Next slide
2 Ionic Compounds or Acid and Ionic
Compound?
yes
no
Double Replacement
Precipitate
Neutralization
Gas
Next slide
Element and Compound?
yes
Single Replacement
Metal
no
Hydrocarbon and O2
Halogen Metallic oxide
no
no
yes
Combustion
????
yes
One Reactant?
no
One Product?
Decomposition
yes
no
Synthesis
2 Ionic Compounds or Acid and Ionic Compound?
yes
no
Double Replacement
Element and Compound?
yes
Precipitate
Gas
no
Neutralization
Hydrocarbon and O2?
Single Replacement
no
????
no
yes
Combustion