Balancing Chemical Equations


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Balancing chemical equations, step by step - Example

Problem 1 :  Example balancing equations:

Balance the chemical equation for combustion of penthane

Step 1. Insert 1 in front of the most complicated looking compound.
1C5H12 + O2 --> CO2 + H2O

Step 2. To balance C's, 5 must be inserted in front of CO2.
1C5H12 + O2 --> 5CO2 + H2O

Step 3. To balance H's, 6 must be inserted in front of H2O .
1C5H12 + O2 --> 5CO2 + 6H2O

Step 4. To balance O's, 8 must be inserted in front of O2 .
1C5H12 + 8O2 = 5CO2 + 6H2O

Erase 1 from the equation:

C5H12 + 8O2 = 5CO2 + 6H2O

The equation is now in balance !
Note: If any fractions should occur, simply multiply the equation by a suitable number. This will be demonstrated in the next problem balancing equations.


Problem 2 :Example balancing equations:

Balance the equation for combustion of ethane

Step 1. Insert 1 in front of the most complicated looking compound.
1C2H6 + O2 --> CO2 + H2O

Step 2. To balance C's, 2 must be inserted in front of CO2.
1C2H6 + O2 --> 2CO2 + H2O

Step 3. To balance H's, 3 must be inserted in front of H2O .
1C2H6 + O2 --> 2CO2 + 3H2O

Step 4. To balance O's, 7/2 must be inserted in front of O2 .
1C2H6 + 7/2O2 = 2CO2 + 3H2O

Step 5. Eliminate the fraction 7/2. This can be done by multiplying the equation by 2.
2C2H6 + 7O2 = 4CO2 + 6H2O

The equation is now in balance !

CHEMIX School - Balancing chemical equations

Balancing chemical equations


Balancing equations - Signs and Symbols

Tab. Guidelines for balancing equations using the CHEMIX School program
Sign/symbol Example Interpretation
+ H2 + O2 .... Separates compounds in equations
> H2 + O2 > H2O Separates left and right side (normally an arrow)
e- Cu + H2O > Cu2O + H+ + e- Electron


 Balancing Chemical Equations - Examples from CHEMIX School program

1) FeS2+O2>Fe3O4+SO2

2) C3H8+O2>CO2+H2O and calculate the amount of CO2 and H2O formed if 2 grams of C3H8 (propane) reacts with O2.

3) C3H8+O2>CO2+H2O and calculate the amount of CO2 and H2O formed if 2 moles of C3H8 (propane) reacts with O2.

4) C3H8+O2>CO2+H2O and calculate the amount of CO2 and H2O formed if 5 grams of C3H8 (propane) reacts with 3 grams of O2.

5) C3H8+O2>CO2+H2O and calculate the amount of CO2 and H2O formed if C3H8 (propane) containing 2 grams of H reacts with 3 grams of O2.

6) As2S3+NaNO3+Na2CO3>Na3AsO4+Na2SO4+NaNO2+CO2 and calculate the amount of As2S3 used forming CO2 containing 10 grams of carbon.

How to download CHEMIX School for balancing equations

For downloading CHEMIX School - simply click the download link at the top of this page. There is more to CHEMIX School than balancing chemical equations. Examples of other tools integrated in CHEMIX School chemistry program are: Molecular weight calculator, periodic table, solubility product calculator, balancing redox equations and much more. Try it.

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