Chemical equation balancer with steps
Type an unbalanced equation and the balancer finds the smallest whole-number coefficients. It shows every step: the atoms in each substance, one equation per element, the solution and a final atom count, so you can follow the method and use it in your exam.
Balanced equation
C₃H₈ + 5 O₂ → 3 CO₂ + 4 H₂O
Write a letter in front of each substance
a C₃H₈ + b O₂ → c CO₂ + d H₂O
Count the atoms of each element
C₃H₈ (a): C 3, H 8
O₂ (b): O 2
CO₂ (c): C 1, O 2
H₂O (d): H 2, O 1
Make the atoms on the left equal the atoms on the right
C: 3a = c
H: 8a = 2d
O: 2b = 2c + d
Set d = 1 and solve
a = 1/4, b = 5/4, c = 3/4, d = 1
Multiply every value by 4 to clear the fractions
a = 1, b = 5, c = 3, d = 4
Check: count the atoms again
C: 3 on the left, 3 on the right
H: 8 on the left, 8 on the right
O: 10 on the left, 10 on the right
How to balance a chemical equation by hand
- Write the correct formulas. Never change a subscript to balance: H2O and H2O2 are different substances.
- Count the atoms of each element on both sides and write the counts under the equation.
- Balance one element at a time by putting numbers in front of formulas. Start with elements found in only one substance on each side, usually metals, then non-metals.
- Leave hydrogen and oxygen until last, because they often appear in several substances.
- Clear any fractions by multiplying every coefficient by the same number, then reduce to the smallest whole numbers.
- Count every atom again. If each element matches, and the charges match for an ionic equation, the equation is balanced.
Worked example: burning propane
- Unbalanced: C3H8 + O2 → CO2 + H2O.
- Carbon: 3 on the left, so write 3 CO2.
- Hydrogen: 8 on the left, so write 4 H2O.
- Oxygen on the right is now 3 × 2 + 4 = 10, so write 5 O2 on the left.
- Balanced: C3H8 + 5 O2 → 3 CO2 + 4 H2O.
Frequently asked questions
What does it mean to balance a chemical equation?
It means choosing whole-number coefficients so that every element has the same number of atoms on both sides. Atoms are not created or destroyed in a reaction, so a correct equation must show the same atoms before and after.
Can I change the small numbers in a formula to balance it?
No. The subscripts are part of the formula: H2O is water and H2O2 is hydrogen peroxide. You may only change the large numbers in front of each formula.
How do I type brackets, hydrates and ions?
Type brackets as normal, for example Ca(OH)2 or Fe2(SO4)3. Write a hydrate with a dot, for example CuSO4.5H2O. Write a charge with a caret, for example Fe^3+, SO4^2- or OH^-, and an electron as e.
Why does the balancer say my equation cannot be balanced?
Usually a formula is wrong, a product is missing, or an element appears on only one side. Check each formula against its name and check the products of the reaction.
How do I balance an equation in WAEC, NECO or JAMB?
Balance the elements that appear in only one substance on each side first, leave hydrogen and oxygen until last, and finish by counting every atom again. In multiple-choice questions you can also test each option by counting atoms.