Reaction Balance Worksheet
Chemistry Lab
Name
Date
Equation Balance Practice
Goal: Make the number of atoms the same on both sides.
The Method: Atom Tally
2
H2
1
O2
2
H2O
Left Side
H: 4
O: 2
Right Side
H: 4
O: 2
1
Write a Coefficient (large number) in the box.
2
Multiply coefficient × subscript to count atoms.
3
Balance the Left and Right sides!
Important: Only change the numbers in the boxes. Never change the small numbers!
Level 1 Foundation
H2 +
Cl2
HCl
Left Side
H: ___
Cl: ___
Right Side
H: ___
Cl: ___
Mg +
O2
MgO
Left Side
Mg: ___
O: ___
Right Side
Mg: ___
O: ___
K +
I2
KI
Left Side
K: ___
I: ___
Right Side
K: ___
I: ___
Level 2 Mastery
N2 +
H2
NH3
Left Side
N: ___
H: ___
Right Side
N: ___
H: ___
Al +
O2
Al2O3
Left Side
Al: ___
O: ___
Right Side
Al: ___
O: ___
Fe +
O2
Fe2O3
Left Side
Fe: ___
O: ___
Right Side
Fe: ___
O: ___
Level 3 Challenge
CH4 +
O2
CO2 +
H2O
Left Side
C: ___
H: ___
O: ___
Right Side
C: ___
H: ___
O: ___
Pb(NO3)2 +
KI
PbI2 +
KNO3
Left Side
Pb: __
NO3: __
K: __
I: __
Right Side
Pb: __
NO3: __
K: __
I: __
Al +
H2SO4
Al2(SO4)3 +
H2
Left Side
Al: __
SO4: __
H: __
Right Side
Al: __
SO4: __
H: __
C3H8 +
O2
CO2 +
H2O
Left Side
C: ___
H: ___
O: ___
Right Side
C: ___
H: ___
O: ___
Balanced!
Check your work: Did you count the atoms on both sides? If they match, the equation is balanced!
Reaction Balance Reference Sheet
Reaction Balance Reference
Use these hints and rules to help you balance chemical equations.
Key Vocabulary
2
Coefficient
The Large Number in front.
Example: 2 H2O
YOU CAN CHANGE THIS!
H2
Subscript
The Small Number below.
Example: H2
NEVER CHANGE THIS!
The Golden Rules
The "No Subscript" Rule
If you change a subscript, you change the chemical! Only change the big numbers in the boxes.
The "Multiply" Rule
Total Atoms = Coefficient × Subscript.
3 H2 = 3 × 2 = 6 Hydrogen atoms.
The "Mirror" Rule
Total atoms on the Left Side (Reactants) must match the Right Side (Products).
Step-by-Step Guide
1
Tally
Count all atoms on both sides.
2
Identify
Find an element that doesn't match.
3
Change
Add a coefficient to fix the count.
4
Re-Check
Check all elements again!
Expert Shortcuts
- O and H Last: Balance Oxygen and Hydrogen at the very end.
- Groups: If you see NO₃ on both sides, count it as 1 unit.
- Even/Odd: If one side is 2 and the other is 3, try to make both sides 6!
Common Ions
NO3 Nitrate
SO4 Sulfate
CO3 Carbonate
PO4 Phosphate
