The document discusses four types of chemical reactions: synthesis, decomposition, single replacement, and double replacement. It provides examples of each type of reaction and describes how to balance chemical equations by ensuring the same number and type of atoms are on both sides of the equation. The key is only changing the coefficients in front of the formulas and not the subscripts inside the formulas.

1. Synthesis, Decomposition, Single,
or Double Replacement?
1. N2 + 3H2 2NH3
1. Synthesis
2. 2Br2 + 2H2O  4HBr + O2
2. Singe
Replacement
3. 2KBr + H2SO4  K2SO4 + 2HBr
3. Double
Replacement
4.
4. H2SO3  H2O + SO2 Decomposition

2. Review
Types of chemical
reactions:
Synthesis
Decomposition
Replacement: single and
double

3. Balancing Equations
Balanced equation- correct
coefficients in place so the same
numbers of, and types of, atoms
appear on both sides of the
equation

4. Balancing Equations
 2H2 + (1)O2  2(H2O(1))
4 hydrogen's +
2 oxygen's 
2 water molecules

5. Balancing Equations
2H2 + (1)O2  2(H2O(1))
4 H’s on the left and right
2 O’s on the left and right

6. Balancing Equations
2H2 + O2  2H2O
 Only change coefficients-
big numbers in front of
equations
 Not subscripts- little
numbers after equations

7. Zn
+
HCl

ZnCl2
+
H2

8. K
+
H 2O

KOH
+
H2

9. H 2O 2
+
PbS

PbSO4 +
H 2O

10. Mg
+
H 2O

Mg(OH)2
+
H2

11. H2 +
H2O2
Na
O2  H2O

+ O2
H2O

+
Na2O
O2

12. N2 +
H2
P4 +
O2
C +
H2

NH3

P4O6

CH4

13. Al2O3

Fe + H2O
Al +

O2
Fe3O4 +
H2

14. C2 H6 + O 2 
CO2 + H2O

15. Na2SO4 + CaCl2
CaSO4 +
NaCl