Types of
Chemical Reactions
Combination Reactions
(aka Synthesis)
= a chemical change in which 2 or more substances react to
form a single new substance
A + B  AB
+

Example:
2K + Cl2  2KCl
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 oxygen gas
Mg(s) + O2(g) 
• Aluminum metal reacts with fluorine gas
Al(s) + F2(g) 
http://www.youtube.com/watc
h?v=tCH3ocXPJwQ&feature=
related
Decomposition Reactions
= a chemical change in which a single compound breaks
down into 2 or more simpler products
AB  A + B

+
Example: 2 HgO  2Hg + O2
http://hogan.
chem.lsu.ed
u/matter/cha
p27/demos/d
m27_013.m
ov
Predict the products!
Write and balance the following decomposition reaction
equations:
• Solid Lead (IV) oxide decomposes
PbO2(s) 
Carbonates and chlorates are
• Limestone decomposes
CaCO3 
• Aluminum nitride decomposes
AlN(s) 
special case decomposition
reactions that do not go to the
elements:
Carbonates (CO32-)
decompose to carbon dioxide
and a metal oxide
Ex: CaCO3  CO2 + CaO
Chlorates (ClO3-) decompose
to oxygen gas and a metal
chloride
GROUP WORK BREAK!:
Dancing with Reactants
http://www.youtube.com/watch?v=jKlxjbhB9HE&e
url=http://video.google.com/videosearch?hl=en&
q=dancing&um=1&ie=UTF8&sa=X&oi=video_result_group&resnumiurl=http
://i3.ytimg.com/vi/jKlxjbhB9HE/hqdefault.jpg
Single Replacement Reactions
= a chemical change in which one element replaces a
second element in a compound
A + BC  AC + B
Example: 2Li + 2H2O  2LiOH + H2
Examples:
2K + 2H2O  2KOH + H2
Potassium replaces hydrogen in water to
form potassium hydroxide and hydrogen
gas.
http://www.youtube.com/watch?
v=OFG4Yr7lQzw
2Na + 2HCl  H2 + 2NaCl
Sodium replaces hydrogen in hydrochloric
acid to yield hydrogen and sodium
chloride.
***Whether one metal will displace another metal from a
compound depends on the relative reactivities of the 2
metals.*** (See Reference Tables: Table J)
A reactive metal
will replace any
metal listed below
it in the activity
series.
A reactive halogen
will replace any
halogen listed
below it in the
activity series.
Predict the products!
Write and balance the following single replacement reaction equations:
• Zinc metal reacts with aqueous hydrochloric acid
Zn(s) + 2HCl(aq) 
• Sodium chloride solid reacts with fluorine gas
NaCl(s) + F2(g) 
• Aluminum metal reacts with aqueous copper (II) nitrate
Al(s)+ Cu(NO3)2(aq)
Double Replacement
Reactions
= a chemical change involving an exchange of positive ions
between 2 compounds
AB + CD  AD + CB
+

+
***For a double replacement reaction to occur, one of the
following should be true:
1.) One of the products is only slightly soluble and
precipitates from solution.
2.) One of the products is a gas.
3.) One product is a molecular compound.
Examples:
MgO + BeS  MgS + BeO
Oxygen and sulfur switch places to form
magnesium sulfide and beryllium oxide.
Na2S + Zn(NO3)2  2Na(NO3) + ZnS
Sulfur and nitrate switch places to form
sodium nitrate and zinc sulfide.
Predict the products!
Write and balance the following double replacement
reaction equations:
1. HCl(aq) + AgNO3(aq) 
2. CaCl2(aq) + Na3PO4(aq) 
3. Pb(NO3)2(aq) + BaCl2(aq) 
4. FeCl3(aq) + NaOH(aq) 
5. H2SO4(aq) + NaOH(aq) 
6. KOH(aq) + CuSO4(aq) 
Combustion Reactions
= a chemical change in which an element or compound
(usually a hydrocarbon) reacts with oxygen
- usually produces carbon dioxide and water
http://hogan.chem.lsu.edu/ma
tter/chap27/demos/dm27_015
.mov
Examples:
• C5H12 + O2  CO2 + H2O
• 2C8H18 + 25O2  16CO2 + 18H2O
• 2Mg + O2  2MgO
• S + O2  SO2