9-2 Day 1 Notes: 5 General Types of Reactions; Synthesis (S) and Decomposition (D).
1.
2.
3.
4.
5.
Type
Abbreviation
Synthesis
Decomposition
Single Replacement - Metal
Single Replacement - Halogen
Double Replacement
Combustion – Metal
Combustion – Hydrocarbon
S
D
SR - M
SR - H
DR
C–M
C – HC
Synthesis / Combination Reactions
DEF: Synthesis / Combination Reaction (S) = A reaction that produces___________________________
X + Y  XY
Ex: 2K + Cl2  2 KCl
Ex: SO2 + H2O  H2SO3
Special Case Synthesis / Combination Reactions
1. non-metal + oxygen  non-metal oxide
Morr than one _________________________________________
You must be told / shown the identity of the product
Ex: S (s) + O2 (g)  SO2 (g)
Ex: 2 S (s) + 3 O2 (g)  2 SO3 (g)
Either one could form!
2. “Special 8” metal + non-metal  ionic cmpd; ratio depends on charge of the special 8 metal
You must be told / shown the charge of the metal’s ion.
3. Metal oxide + water  _________________
DEF: Base = ________________________________________________________________________
Ex: CaO (s) + H2O (l)  Ca(OH)2 (aq)
Ex: Na2) (s) + H2O (l)  2 NaOH (aq)
4. Nonmetal oxide + water  __________________________________________________________
Count total # of H’s, place up front; nonmetal next; O last
Ex: H2O (g) + SO3 (g)  H2SO4 (aq)
5. Metal + water  _________ + ____________ BOOM!!!!
Ex: Mg (s) + 2 H2O (l)  Mg(OH)2 (aq) + H2 (g)
Decomposition Reactions
XY  X + Y
DEF: Decomposition Reaction (D) = A reaction that has ________________________________________
Ex: H2O (l)  H2 (g) + O2 (g)
Ex: HgO (s)  Hg (l) + O2 (g)
If you are given only one reactant followed immediately by an arrow, assume it’s a decomposition rxn, and separate it into it’s
parts.
Types:
A.
B.
C.
BIC’s  metal + nonmetal
Acids  Nonmetal oxide + water (self-balances)
Bases  metal oxide + water
You Try It! Write and Balance Each
1. KBr 
2. H2SO3 
3. SnCl4 
4. Al + S 
5. K + H2O 
6. NaO + H2O 
7. SO2 + H2O 