Chemical Equation Balancer
Balance any chemical equation, ionic and redox ones included, exactly; then find the limiting reagent, the theoretical yield, what is left over and the percent yield.
Result
| Element | Left | Right |
|---|---|---|
| K | 2 | 2 ✓ equal |
| Mn | 2 | 2 ✓ equal |
| O | 8 | 8 ✓ equal |
| H | 16 | 16 ✓ equal |
| Cl | 16 | 16 ✓ equal |
- Coefficients are the smallest whole numbers that conserve every element, found exactly (no rounding).
- Balancing checks the atoms, not whether the reaction happens: the products are yours to get right.
Equation
Read as: KMnO₄ + HCl → KCl + MnCl₂ + H₂O + Cl₂
Amounts and yield
Enter the amount of one or more reactants. A reactant left blank is taken to be in excess. Add the mass you actually made to see the percent yield.
| Species | Coefficient | Molar mass (g/mol) | You have | Reacts / forms (mol) | Reacts / forms (g) | Left over (g) |
|---|---|---|---|---|---|---|
| KMnO₄ | 2 | 158.03 | — | — | — | |
| HCl | 16 | 36.458 | — | — | — | |
| KClProducts | 2 | 74.548 | — | — | — | |
| MnCl₂ | 2 | 125.84 | — | — | — | |
| H₂O | 8 | 18.015 | — | — | — | |
| Cl₂ | 5 | 70.9 | — | — | — |
How is this calculated?
Each element gives one equation Σ(atoms × coefficient) on the left = on the right, plus one for charge; the coefficients are the null space of that matrix, scaled to the smallest whole numbers. Limiting reagent: the smallest moles ÷ coefficient.Runs in your browser — nothing you enter leaves this device.
About this tool
What it does
Type a chemical equation and it is balanced as you type: the smallest whole-number coefficients that put the same number of every atom on each side. It handles brackets and nested groups (Ca3(PO4)2, K4[Fe(CN)6]), hydrates (CuSO4·5H2O) and ionic equations with charges and electrons, where the charge must balance too — so half-equations and redox equations in acid work (MnO4− with Fe²⁺ and H⁺). The answer is found with exact fraction arithmetic rather than trial and error or rounded decimals, so a large equation such as the oxidation of potassium ferrocyanide by permanganate comes out right, with coefficients in the hundreds. A table underneath counts every element (and the charge) on each side so you can see it balances. If an equation cannot be balanced, the page says why: an element appears on one side only, a species would have to change sides, or the equation is really two reactions written together and balances in more than one way. Below the answer is the stoichiometry: enter how much of each reactant you have, in grams, milligrams, kilograms or moles, and the page finds the limiting reagent, the moles and grams of every product it can form, and what is left of each reactant. Type the mass you actually collected beside a product to get your percent yield. Copy the balanced equation with proper subscripts, or as plain text for a spreadsheet, and Copy link saves the equation in the address.
How to use it
- Type the equation: reactants, an arrow (-> or =), products, with + between species. Coefficients you type are ignored.
- Write charges as Fe^3+ or Fe{3+}, single charges as OH- or NH4+, and an electron as e-.
- Read the balanced equation and the check table, and copy it.
- Enter the amounts of your reactants for the limiting reagent, the yields and the leftovers.
Limits and your data
- Balancing checks atoms and charge, not chemistry: it cannot tell whether the reaction happens, or whether you have the right products.
- A trailing sign is a single charge (NH4+ is ammonium). Fe3+ is read as Fe₃ with a charge of 1+; for iron(III) write Fe^3+. The page shows how it read each species.
- States such as (aq) or (s) are not part of a formula; leave them out.
- Molar masses use IUPAC’s standard atomic weights; yields are theoretical, assuming the reaction goes to completion.
- The balancing and every calculation happen in your browser, and work offline. Nothing is sent anywhere.
Questions
How do I balance a redox equation?
Write every species including H+ and H2O (in acid) or OH− and H2O (in base), with charges: MnO4- + Fe^2+ + H+ -> Mn^2+ + Fe^3+ + H2O. The charge is balanced along with the atoms.
What is the limiting reagent?
The reactant that runs out first. Divide the moles of each reactant by its coefficient; the smallest result is the limiting one, and it sets how much product can form.
Why does it say the equation balances in more than one way?
Two independent reactions have been written as one (for example water splitting into both H2O2 and O3). Any mixture of them balances, so there is no single answer. Remove a product or split the equation.
How is percent yield worked out?
The mass you actually collected divided by the theoretical yield, times 100. Type your mass beside the product once the reactant amounts are entered.