Download Part B: Balancing Equations Magic Number

Chemistry I
Discovery 5-1
Balancing Equations
Name
Period
Part A: What is a Balanced Equation?
What does it mean for an equation to be balanced? It means there are the same numbers of
“things” on both sides of the equation. For example:
(a) 1 center + 2 guards + 2 forwards = 1 basketball team
(b) 9 girls + 14 boys = 10 lab pairs + 1 group of three
Each side of the equation represents the same number of people; they are just arranged
differently. The same occurs in balanced chemical equations. Each side of the equation
represents the same number of atoms but they are arranged differently (in different compounds).
For example:
2 H2 + O2  2 H2O
On the reactants side of the equation, there are 4 hydrogen atoms and 2 oxygen atoms. On the
products side, there are 4 hydrogen atoms and 2 oxygen atoms. Therefore, the chemical equation
is balanced.
1. Is the chemical equation balanced? List the number of each type of atom on the reactants
side and the number of each type on the products side. Are they the same or different?
Equation
Reactant
Product
Is it
Atoms
Atoms
balanced?
2 Na + 2 H2O  2 NaOH + H2
Na:
Na:
H:
H:
O:
O:
4 Al + 3 O2
 2 Al2O3
Al:
Al:
O:
O:
P4
+ 5 O2  P2O5
P:
P:
O:
O:
C3H8 + O2  3 CO2 + 4 H2O C:
C:
H:
H:
O:
O:
2. You should have gotten two unbalanced equations above. What coefficients could you add
in front of the reactants or products to make the equation balance? Add the correct
coefficients to balance the equations above.
3. Determine how many of both the reactants and products you need to balance the equation.
Add the correct coefficients to balance the equation.
a.
Fe2O3
+
H2 
Fe +
H2O
b.
C2H6
+
O2 
CO2 +
H2O
4. If a chemical equation has the same polyatomic ion on both sides of the equation, keep it
together as a group. Use the phosphate ion and hydroxide ion from your “atoms” to help you
balance these last equations. Add the correct coefficients to balance the equation.
a.
MgCl2
+
LiOH 
LiCl +
Mg(OH)2
b.
Ca(OH)2
+
H3PO4

Ca3(PO4)2
+
H2O
Chemistry I
Part B: Balancing Equations Magic Number
Place coefficients in front of each compound in the following chemical equations. Your goal is
to end up with the same number of each type of atom on the reactants side and products side of
the equation. Then, add up the coefficients and write the answer in the box. Next, add up all the
numbers in the boxes. The Magic Number is:
119
.
1)
Ag2O 
Ag
+
O2
2)
C4H8 +
O2

CO2 +
3)
Al
+
N2

AlN
3
4)
Li
+
O2

Li2O
4
5)
C3H6 +
O2

CO2 +
H2O
5
6)
Na3PO4 +
Pb(NO3)2 
Pb3(PO4)2 +
NaNO3
6
7)
C2H2 +
O2
CO2 +
H2O
7
8)
Al
CuSO4
9)
C2H6 +
O2
10)
Al2(SO4)3 +
Ca(OH)2 
+


Al2(SO4)3
1
H2O
+
2
Cu
CO2 +
H2O
Al(OH)3 +
CaSO4
8
9
10