Answer Key
Names:______________________________________ Pd: ______ Date: ________________
Score
More Balancing Chemical Equations
Directions:, Use your knowledge of Chemical Equations to write the correct coefficients
for the reactants and products list below, so that each chemical equation is balanced.
Remember coefficients of ONE do not need to be written.
Problem #1
3
_____KOH
+
_____H3PO4
K=1=
Step 1) Coefficient of 3 for KOH
Step 2) Coefficient of 3 for H2O
3
Step 1) Coefficient of 3 for H2O
Step 2) Coefficient of 2 for NH3
Step 3) Coefficient of 2 for NO
Step 4) Coefficient of 2 ½ for O2
Step 5) Double all Coefficients to
eliminate the fraction
K = 3=
5
P=1
P=1
Problem #2
4
_____NH
+
3
3
_____K3PO4 + _____H
2O
H=4=
6
H=2=
6
O=5=
7
O=5=
7
5 O2
_____
4
_____NO
N=1=
24
N = 1=
24
H=3=
6  12
H=2=
6  12
O=2=
5  10
O=2=4=
+
5  10
Problem #3
4
_____Al
+
Step 1) Coefficient of 2 for Al
Step 2) Coefficient of 3 for O2
Step 3) Coefficient of 2 for Al2O3
Step 4) Change coefficient to 4 for Al
3 2
_____O
2 2O 3
_____Al
Al = 1 =
2=4
Al = 2 =
4
O=2=
6
O=3=
6
6 2O
_____H
Problem #4
_____CO
8
+ _____H
17 2
Step 1) Coefficient of 8 for CO
Step 2) Coefficient of 10 for H2
Step 3) Coefficient of 8 for H2O
Step 4) Change coefficient to 17 for H2
C=1=
______C8H18
8
C=8=
H = 2 = 20
O=1=
= 34
8
2
H = 20 =
O=1
+ _____H
8 2O
34
=8
Problem #5
_____Au2S3
Step 1) Coefficient of 2 for Au
Step 2) Coefficient of 3 for H2S
Step 3) Coefficient of 3 for H2
+ _____H
3 2
_____Au
2
+ _____H
3 2S
Au = 2
Au = 1=
2
S=3
S=1=
3
H=2=
6
H=2=
6
Problem #6
_____CaCl
3
2
+ _____Na
2
3PO4
Ca = 1 =
Step 1) Coefficient of 3 for CaCl2
Step 2) Coefficient of 6 for NaCl
Step 3) Coefficient of 2 for Na3PO4
Cl = 2 =
3
6
Na = 3 =
6
P=1=
2
O=4=
8
_____Ca3(PO4)2
+ _____NaCl
6
Ca = 3
Cl = 1 =
6
Na = 1 =
6
P=2
O=8
Problem #7
12 HClO4 + _____P4O10
_____
Step 1) Coefficient of 4 for H3PO4
Step 2) Coefficient of 2 for HClO4
Step 3) Change coefficient to 12 for HClO4
Step 4) Coefficient of 6 for Cl2O7
Cl = 1 = 2
4 3PO4
_____H
= 12
P=4
H=1=
2 = 12
O = 14 = 18
= 58
6 2O 7
+ _____Cl
Cl = 2=
24
P=1=
4
H=3=
12
O = 11 = = 23
= 23