Single Replacement Reactions: A BC ? AC B

1
Single Replacement Reactions A BC ? AC B
An element takes the place of another element in
a compound. It could be a metal taking the place
of another metal or hydrogen or a halogen taking
the place of another halogen.
MgSO4 (aq) Fe(s)
Mg(s) FeSO4(aq) ? Cl2(g) KBr(aq) ?
Fe(s) MgSO4 (aq) ? Br2 (aq) KCl(aq) ?
Magnesium is more active than Iron and
KCl(aq) Br2 (aq)
Chlorine is more active than Bromine!
N.R.
N.R.
2
Activity Series
Lithium
For metals
Li Cs Rb K Ba Sr Ca Na La Mg Be Al Mn Zn Cr Fe Cd
Co Ni Sn Pb H
Cesium
Rubidium
Potassium
Barium
For halogens
Strontium
Activity Decreases
Calcium
Sodium
F Cl Br I
Fluorine
Activity Decreases
Lanthanum
Magnesium
Chlorine
Beryllium
Bromine
Aluminum
Iodine
Manganese
Zinc
H Cu Hg Ag Pt Au
Chromium
Hydrogen
Iron
Copper
Cadmium
Mercury
Cobalt
Nickel
Silver
Tin
Platinum
Lead
Gold
Hydrogen
3
Double Replacement Reactions
AB CD ? AD CB
It is a reaction between two ionic compounds in
which the ions switch positions The positive
of the first combines with the negative of the
second and the positive of the second with the
negative of the first.
MgCO3(s) FeSO4(aq) ? BaCl2(aq)
KBr(aq) ? Fe(NO3)3(aq)Ca3(PO4)2(s)? CuBr2
(aq) KCl(aq) ?
MgSO4 (aq) FeCO3 (s)
BaBr2(aq) KCl(aq)
2
2
Ca(NO3)2(aq) FePO3(s)
2
2
3
CuCl2 (aq) KBr(aq)
2
2
4
Double-replacement reactions
One of the types of double-replacement reactions
is when a precipitate is formed. When a
precipitate is formed, the compound will be
either insoluble or slightly soluble. An example
of this type of reaction is
Pb(NO3)2(aq) 2KI (aq) --gt
PbI2(s) 2KNO3 (aq)
When one of the products is a gas,
double-replacement reactions also occur. For
example FeS(s) 2HCl(aq)
--gt
H2S(g) FeCl2(aq)
An example of a double-replacement reaction where
water is one of the products is HCl(aq)
NaOH(aq) --gt
NaCl (aq) H2O(l)
This is a neutralization reaction Acid
Base Salt Water
http//www.cameron.k12.wi.us/high/chemistry/drreac
.html
5
Combustion of a hydrocarbon
HydrocarbonO2(g)?C O2(g)H2O(g)
When a substance combines with oxygen releasing a
large amount of energy in the form of light and
heat, it is a combustion reaction. An example of
a combustion reaction is
C3H8 5O2 --gt
3CO2 4H2O


?
http//www.cameron.k12.wi.us/high/chemistry/comrea
c.html http//newtraditions.chem.wisc.edu/FPTS/fbe
qns/eqncombf.htm
6
Decomposition Reactions ABC ? A B C
Decomposition the breaking down of a compound
into one or more substances. (usually energy is
required)
EXAMPLES CO2 (g) -----? C(s) O2(g)
2Fe2O3 (s)-? 4Fe(s) 3O2 (g)

• Generalizations
• A binary compound decomposes into two elements.
• A hydroxide of the metal decomposes into an oxide
  of the metal and water.
• A ternary salt decomposes into an oxide of the
  metal and an oxide of the non metal.
• A ternary or oxoacid decomposes into the oxide of
  a non metal and water .