pchem types of chem reactions

1. Types of Chemical
Reactions
Predicting Products
from the Reactants

2. Types of Reactions
1. Synthesis reactions
2. Decomposition reactions
3. Single displacement reactions
4. Double displacement reactions
5. Combustion reactions
You need to be able to identify each

3. 1. Synthesis
Example C + O2
O
O
C +  O O
C
Synthesis: A + B  AB

4. Criss Cross the Charges to
Balance
• Mg + N  ?
• Mg = +2
• N = -3
+2 -3
• Mg + N 
• Synthesis: A + B = AB
Mg3N2

5. Ex. Synthesis Reaction

6. Practice
• Predict the products:
Na(s) + Cl2(g) 
Mg(s) + F2(g) 
Al(s) + F2(g) 
NaCl(s)
MgF2(s)
AlF3(s)
2
2 3 2
• Now, balance them. (Criss-Cross!)
2

7. But WAIT! What Does the
(s) and (aq) and (g) Mean???
• (s) in a chemical equation signifies a
SOLID
• (g) in a chemical equation is a GAS
• (aq) means “aqueous” (LIQUID)
• Why do you need to note that?
Because sometimes… a phase can
change in a reaction!

8. 2. Decomposition
Example: NaCl
General: AB  A + B

Cl Na Cl + Na
Compound = Element + Element

9. Ex. Decomposition Reaction

10. 3. Single Displacement
Example: Zn + CuCl2

Zn
Cl
Cl
Cu +
General: AB + C  AC + B
Cl
Cl
Zn Cu
+
Zn was oxidized
Went from neutral (0) to (+2)
Cu was reduced
Went from (+2) to Neutral (0)
Compound + Element = New Compound + New Element

11. But WAIT! What do
“oxidized” and ”reduced” Mean?
• Remember?
• LEO the lion says GER
• Lose electrons = oxidation = LEO
• Gain electrons = reduction = GER
• Metals LOSE electrons
• Non-metals GAIN electrons

12. Ex. Single Replacement Reaction

13. Single Replacement Reactions
• Write and balance the following single
replacement reaction equations:
• Zn(s) + HCl(aq) 
2
• NaCl(s) + F2(g) 
• Al(s)+ Cu(NO3)2(aq)
2 2
Cu(s)+ Al(NO3)3(aq)
3 2
3
2
ZnCl2 + H2(g)
NaF(s) + Cl2(g)

14. 4. Double Displacement
Example: MgO + CaS
General: AB + CD  AD + CB
S
O

Mg Ca
+
O
S
Mg Ca
+

15. Double Replacement Reactions
• Think about it like “foil”ing in algebra, first
and outer ions go together + inside ions go
together
• Example:
AgNO3(aq) + NaCl(s)  AgCl(s) + NaNO3(aq)
• Another example:
K2SO4(aq) + Ba(NO3)2(aq)  KNO3(aq) + BaSO4(s)
2

16. Practice
• Predict the products:
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) 

17. 5. Combustion Reactions
• Combustion reactions –
when a hydrocarbon reacts
with oxygen gas
• This is also called
BURNING!
• In order to burn something
you need the 3 things in
the “fire triangle”:
• 1) Fuel (hydrocarbon)
2) Oxygen
3) Something to ignite the
reaction (spark)

18. Combustion Reactions
• In general:
CxHy + O2  CO2 + H2O
• Products are ALWAYS
CARBON DIOXIDE AND WATER!
• Combustion is used to heat homes and run
automobiles (octane, as in gasoline, is a
hydrocarbon: C8H18 )

19. Mixed Practice
• State the type of reaction & predict
the products (try to balance the
equation!)
1. BaCl2 + H2SO4 
2. C6H12 + O2 
3. Zn + CuSO4 
4. Cs + Br2 
5. FeCO3 