How to use the chemical reaction calculator
- Choose Balance, Scale quantities, or Find limiting.
- Enter reactants on the left and known products on the right.
- Use spaces around each plus sign and place an arrow between both sides.
- Enter quantities only when the selected mode requires them.
- Calculate and review the verified equation, table, and step-by-step method.
One reaction, three calculations
Start with the equation. Add quantity data only when the problem asks for a scaled reaction or a limiting reactant.
| Mode | Use it when | Result |
|---|---|---|
| Balance | You know the reactants and products | Coefficients, pattern, molar masses, and conservation checks |
| Scale quantities | You know one species quantity | Required reactants and produced products in moles and grams |
| Find limiting | You know every reactant quantity | Limiting reactant, excess, and maximum product |
Balancing and stoichiometry formulas
A x = 0; reaction extent = n_i / coefficient_i
| Symbol | Meaning | Unit |
|---|---|---|
| A | element and charge conservation matrix | atom counts |
| x | smallest integer coefficient vector | dimensionless |
| n_i | species amount | mol |
Worked example
For H2 + O2 -> H2O, the result is 2 H2 + O2 -> 2 H2O. It verifies four H atoms and two O atoms on each side.
Supported chemical equation formats
Formula capitalization is significant. Spaces around each plus sign distinguish a species separator from an ionic charge.
| Equation type | Example input | What is preserved |
|---|---|---|
| Molecular | C2H6 + O2 -> CO2 + H2O | Smallest whole-number coefficients |
| Physical states | H2(g) + O2(g) -> H2O(l) | State labels retained in the result |
| Ionic charge | Fe2+ + Ce4+ -> Fe3+ + Ce3+ | Atoms and net charge conserved |
| Equilibrium | N2 + H2 <=> NH3 | Equilibrium arrow retained |
How to read the reaction result
The smallest whole-number coefficients conserve every element and net charge. Scaled quantities use that exact coefficient ratio.
Common mistakes
- Use spaces around plus signs so the parser can distinguish species separators from ionic charges.
- Enter known products. The calculator does not guess products or invent missing reaction conditions.
- Do not change chemical subscripts to balance an equation because that changes the substances.
Frequently asked questions
Does this calculator predict reaction products?
No. Products depend on conditions and competing pathways. Enter known products so the result stays chemically defensible.
Can I use an unbalanced equation?
Yes. Every mode balances the equation before it performs stoichiometric calculations.
Can I balance ionic equations?
Yes. Enter explicit ionic charges. The exact conservation matrix includes a net-charge row.
What does Scale quantities calculate?
It converts one known species quantity into the required reactant amounts and produced product amounts.
How does the calculator find the limiting reactant?
It converts every reactant to moles and compares each amount divided by its balanced coefficient.
Which quantity units are supported?
Use mass, moles, millimoles, micromoles, nanomoles, picomoles, or particle count.
Can I include physical states?
Yes. Add (s), (l), (g), or (aq) after a species formula.
Does the calculator change chemical subscripts?
No. It changes coefficients only because changing a subscript would create a different substance.
Can I use scientific notation?
Yes. Enter values such as 6.022e23 or 1.0e-6 in a numeric field.
How should I round the result?
Keep extra digits during the calculation. Round the final result to the precision required by your data.