How to use it
- Type the reaction with reactants and products separated by
+and an arrow:->,→or=. - Brackets and hydrates are understood:
Al2(SO4)3,CuSO4·5H2O. Ions are not yet. - The balanced equation appears as you type, and the table counts each element on the left and on the right.
- The address bar holds the equation, so a link brings the same result back.
What balanced means
In a chemical reaction atoms are neither created nor destroyed, so each element must occur as many times after the arrow as before it. Only the coefficients in front of the formulas may change, never the subscripts inside them. Propane burning:
C₃H₈ + 5 O₂ → 3 CO₂ + 4 H₂O
Carbon: 3 = 3. Hydrogen: 8 = 4 · 2. Oxygen: 5 · 2 = 3 · 2 + 4.
How the calculator finds the coefficients
Each substance is a column of atom counts, positive for a reactant and negative for a product. A balanced equation is a set of coefficients for which every element’s row adds up to zero. The calculator solves that with exact fractions and scales the answer to the smallest whole numbers, so there are no rounded decimals. The same method balances the hard cases, such as 2 KMnO₄ + 16 HCl → 2 KCl + 2 MnCl₂ + 5 Cl₂ + 8 H₂O.
When it says no
- An element on only one side of the arrow cannot be balanced by any coefficient: check the formulas.
- If the substances take part in several reactions at once, the coefficients are not unique. Split the equation into one reaction at a time.
- If a coefficient would have to be zero or negative, a substance is on the wrong side of the arrow.
Next: the molar mass calculator turns the formulas into grams per mole.