
N2 + Li 

Na + Br2 

Mg + I2 

K+S
Something breaks apart into individual pieces.
Opposite of synthesis reactions.
 Couple breaks up 
 Ex. 2NaCl  2Na + Cl2



You need to know four types
 Binary
 Metallic Carbonates
 Metallic Hydroxides
 Metallic Chlorates
A compound breaks up into its elements
 AB  A + B
 2NaCl  2Na + Cl2
 Exact opposite of synthesis!

Decompose into the metal oxide and Carbon
Dioxide
 MCO3  MO + CO2
 PbCO3  PbO + CO2

Decompose into the metal oxide and water
 MOH  MO + H2O
 Pb(OH)2  PbO + H2O

Decompose into the metal chloride and oxygen gas
 MClO3  MCl + O2
 Pb(ClO3)2  PbCl2 + 3O2

Determine the type of compound before trying to
predict the products!!
 Use the “Guidelines for Predicting the Products of
selected Types of Chemical Reaction” reference
sheet


Cu(OH)2 

Li + O2 

CaCl2 

Mg + Cl2 

Fe(ClO3)3 

Na + Br2 

NiCO3 

K+S
Unit 6, Day 4
Kimrey
31 October 2012

A Carbon containing compound reacts with oxygen.
Carbon dioxide and water are always your products!

So, predicting products is pretty simple.
C6H12O6 + O2  H2O + CO2
 Products will always be CO2 and H2O
 Look for a carbon containing
compound and O2 as a reactants.
 The only work you have to do is
balance the equation correctly.
CH4 + O2 
 CH4 + 2O2  CO2 + 2H2O
 Cs + F2 
 2Cs + F2  2CsF
 Ba + Cl2 
 Ba + Cl2  BaCl2
 C3H8 + O2 
 C3H8 + 5O2  3CO2 + 4H2O


What is a single replacement reaction?

One “kicks” out the less reactive element.
 Ex. 2Na (s) +2HCl(aq)  2NaCl(aq) + H2(g)

Metals range in reactivity
 Some are very stable as elements
▪ These are less reactive
▪ Example: Gold, Au
 Some are very reactive
▪ These are mostly found in compounds (not by
themselves)
▪ Example: Sodium, Na




The most active metals are at the top of the
series
An elemental metal can replace any metallic
ion that is BELOW it on the series
If an element is more reactive, it will replace
the less reactive ion in a compound.
You will always be given the activity series as
a reference table
How to use the activity series.
Find the element in the compound on the
table.
2. Find the Solo element
3. If the solo element is above the element in
the compound then the reaction will take
place.

1.
2Al(s) + 3ZnCl2(aq)  3Zn(s) + 2AlCl3(aq)
To replace the Zinc, Aluminum must be higher
on the series
Cu(s) + 2NaCl(aq)  NO REACTION
Can copper replace sodium in the compound?



Above the activity series for metals, there is
an activity series for Halogens.
If your solo element is a halogen, it will
replace the bonded halogen as long as it is
above it on the activity series.
Remember, every halogen on the series is a
diatomic molecule, so when it’s by itself,
there will be two of them (F2, Br2, …)
• Cr(s) + Pb(NO3)2(aq)  Cr(NO3)2(aq) + Pb(s)
• Pt(s) + CaCl2(aq)  NO REACTION
• Ca(s) + FeO (aq)  CaO (aq) + Fe(s)