1. Types of
Reactions

2. Five Types of Reactions
Synthesis
Decomposition
Single Replacement
Double Replacement
Combustion

3. 1. Synthesis A + X a AX Mg + S a MgS 4 Fe + 3 O2 a 2 Fe2O3
Examples:
Mg + S a MgS
4 Fe O2 a 2 Fe2O3
N H2 a 2 NH3 2
Na + S a
Na2S
Na+1S-2 2
Ca + O2 a
2 CaO
Ca+2O-2
CaO
NH H2O a NH4OH
Synthesis reactions can be recognized by 2 or more substances producing one.

4. 2. Decomposition AX a A + X electricity 2 H2O a 2 H2 + O2
CaCO3 a CaO + CO2
D means heat
2 NH3 a N H2
NH3 a N H2
Decomposition reactions can be recognized by 1 substance producing 2 or more.

5. 3. Single Replacement AX + B a BX + A or
AX + Y a AY + X
If B is a metal, it will replace the metal, A
AX + B a BX + A A X B
If Y is a nonmetal, it will replace the nonmetal, X
AX + Y a AY + X A X Y

6. Example:
SrBr2 + Cl2 a
SrCl2 + Br2
nonmetal 2
NaCl + F2 a
2 NaF + Cl2
Na+1F Cl2
Ca + ZnO a
Zn + CaO
metal
Ca a 2
H2O
HOH
Ca(OH)2 + H2
Ca+2OH H2
think of water as HOH
metal

7. Some replacement reactions are not possible.
In order for an element to be replaced, it has to be less active than the element that is replacing it.
For example, the reaction
Zn + CaCl2 a no reaction
Zn is not more active than Ca. So it cannot replace it.

8. Activity Series for single replacement reactions Nonmetals Fluorine
Lithium
Potassium
Barium
Calcium
Sodium
Magnesium
Aluminum
Manganese
Zinc
Chromium
Iron
Cobalt
Nickel
Tin
Lead
Hydrogen
Copper
Silver
Mercury
Platinum
Gold
Nonmetals
Fluorine
Chlorine
Bromine
Zn + CaCl2 a no reaction
decreasing activity
Ca + ZnCl2 a CaCl2 + Zn

9. 4. Double Replacement AX + BY a BX + AY2
KI + Pb(NO3)2 a +
PbI2
Pb+2I-1 K I Pb
K+1
2 KNO3
KNO3
NO3
NO3-1
(balance the equation)
(correct formulas)
(switch places)
(check the charges)

10. HCl + Mg(OH)2 a
(switch places)
HCl + Mg(OH)2 a MgCl + HOH
check the charges
HCl + Mg(OH)2 a Mg+2Cl H+1OH-1
correct formulas
HCl + Mg(OH)2 a MgCl HOH
balance the equation
2HCl + Mg(OH)2 a MgCl HOH
or H2O

11. (switch places)
FeS + HCl a
FeS + HCl a FeCl + HS
check the charges
FeS + HCl a Fe+2Cl H+1S-2
correct formulas
FeS + HCl a FeCl2 + H2S
balance the equation
FeS HCl a FeCl2 + H2S

12. 5. Combustion of hydrocarbons
CxHy + O2 a CO H2O complete combustion
CxHy + O2 a CO H2O incomplete combustion
Hydrocarbons are usually fuels.
CH4 methane C3H8 propane (LP gas)
C4H10 butane C8H18 octane (gasoline)

13. The reaction for the complete combustion of methane:
CH O2 a
predict the products
CH O2 a CO2 + H2O
balance the equation
CH O2 a CO H2O
CH O2 a CO H2O

14. The reaction for the incomplete combustion of propane:
C3H8
+ O2 a
CO H2O
balance the equation
C3H O2 a 3 CO H2O
C3H O2 a 3 CO H2O
7 oxygens
C3H ½ O2 a 3 CO H2O
multiply by 2
2 C3H O2 a 6 CO H2O

15. 5. Combustion of hydrocarbons
1. Synthesis
A + X a AX
2. Decomposition AX a A + X
3. Single Replacement AX + B a BX + A or
AX + Y a AY + X
4. Double Replacement AX + BY a BX + AY
5. Combustion of hydrocarbons
CxHy + O2 a CO H2O complete combustion
CxHy + O2 a CO H2O incomplete combustion