Chemical Equation Balancer: Balance a Chemical Equation Step by Step with Atom Count
Find the coefficients that balance a reaction.
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How this calculator works
Type the equation with an arrow between reactants and products.
Write formulas without numbers in front.
The calculator gives the balanced equation and the atom check.
Formulas used
- N_{left}(\text{element}) = N_{right}(\text{element})
Worked example
With the default numbers in the calculator above:
- Balanced equation: C3H8 + 5 O2 -> 3 CO2 + 4 H2O
- Coefficients: C3H8 = 1, O2 = 5, CO2 = 3, H2O = 4
- Atoms of each element (left = right): C: 3 = 3; H: 8 = 8; O: 10 = 10
Change the numbers in the calculator to see the full working, every step, for your own case.
A second worked example
A different case, with these numbers: The equation Fe + O2 -> Fe2O3.
- Balanced equation: 4 Fe + 3 O2 -> 2 Fe2O3
- Coefficients: Fe = 4, O2 = 3, Fe2O3 = 2
- Atoms of each element (left = right): Fe: 4 = 4; O: 6 = 6
Common questions
How do you balance a chemical equation?
Choose coefficients so that each element has the same number of atoms on both sides. The calculator solves this as a set of equations.
Why must an equation be balanced?
Atoms are not created or destroyed in a chemical reaction, so their numbers must match on both sides.
Why can some equations not be balanced?
If an element appears only on one side, or the formulas are wrong, no set of coefficients works.
Related calculators
Got a question about this? Ask an engineering question and get a plain-language answer with references.
Further reading: Any chemistry text (balancing chemical equations).
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