Balance equations
Type it. Watch every atom match.
Balance an equation
4Fe+3O₂→2Fe₂O₃
Balanced
Atoms on each side
| Atom | As writtenleft : right | Balancedleft : right |
|---|---|---|
| Fe | 1:2 | 4:4 |
| O | 2:3 | 6:6 |
Check atoms
How to balance it
- Count the atoms of each element on both sides, as written.
- Start with the biggest formula, Fe₂O₃: put 1 in front of it.
- Fe: 2 on the right. Put 2 in front of Fe.
- O: 3 on the right. Put 3/2 in front of O₂ (3/2 × 2 = 3).
- Clear the fraction: multiply every coefficient by 2.
- Check: Fe 4 = 4, O 6 = 6. Balanced.
Pick an equation
Photosynthesis
Respiration
Combination
Combustion
Displacement
- Sodium and water
- Potassium and water
- Calcium and water
- Zinc and hydrochloric acid
- Magnesium and hydrochloric acid
- Aluminium and hydrochloric acid
- Aluminium and copper chloride
- Copper and silver nitrate
- Zinc and copper sulphate
- Iron and copper sulphate
- Zinc and sulphuric acid
- Thermite reaction
- Chlorine and potassium iodide
- Bromine and potassium iodide
- Lithium and water
Neutralisation
Decomposition
Double displacement
Fermentation
Same chapter: organic conversions, name reactions, electron configuration, oxidation numbers and redox, bonding and shapes, mole calculator.
Balancing chemical equations
How do I balance a chemical equation?
Count the atoms of each element on both sides. Put whole numbers, called coefficients, in front of the formulas until every element has the same count on both sides. Start with the element that appears in the fewest formulas and leave hydrogen and oxygen for last.
Why can I not change the subscripts?
A subscript is part of the formula. Changing H₂O to H₂O₂ turns water into hydrogen peroxide, a different substance. Only the coefficients in front of the formulas may change.
How does the balancer work?
Each element gives one equation in the unknown coefficients, and the balancer solves them exactly with fractions, then scales to the smallest whole numbers. The steps shown are the by-hand method that reaches the same answer.
Can it balance ionic equations?
Yes. Type charges after the formula, such as Fe3+, OH- or SO4 2-, and electrons as e-. The total charge is balanced along with the atoms.
What does it mean when an equation cannot be balanced?
Either an element appears on one side only, or no set of whole numbers makes every count match. Check each formula and which side it is on. If it balances in more than one way, it is two reactions written as one.