Calculator Inputs
Enter up to three reactants. Use grams or moles. When grams are entered, add molar mass so the calculator can convert each reactant to moles.
Example Data Table
Sample reaction: 2H₂ + O₂ → 2H₂O
| Reactant | Coefficient | Input Amount | Unit | Molar Mass (g/mol) | Converted Moles | Reaction Units |
|---|---|---|---|---|---|---|
| H₂ | 2 | 10 | g | 2.016 | 4.9603 | 2.4802 |
| O₂ | 1 | 20 | g | 31.998 | 0.6250 | 0.6250 |
In this example, O₂ is limiting because it provides fewer reaction units than H₂. Theoretical H₂O produced equals 2 × 0.6250 = 1.2500 mol.
Formula Used
- Moles from grams: moles = mass ÷ molar mass
- Reaction units for each reactant: reaction units = available moles ÷ stoichiometric coefficient
- Limiting reactant: the reactant with the smallest reaction units value
- Consumed moles: consumed moles = reactant coefficient × limiting reaction extent
- Leftover moles: leftover moles = available moles − consumed moles
- Theoretical product moles: product moles = product coefficient × limiting reaction extent
- Theoretical product mass: product mass = theoretical product moles × product molar mass
- Percent yield: percent yield = (actual product mass ÷ theoretical product mass) × 100
How to Use This Calculator
- Enter a reaction name and balanced equation for easy reference.
- Add the desired product name, product coefficient, and product molar mass.
- For each reactant, enter the name, balanced coefficient, available amount, and unit.
- If a reactant amount is entered in grams, also enter its molar mass.
- Click Calculate Limiting Reactant to see the limiting reagent, excess amounts, and theoretical yield above the form.
- Review the results table and chart to compare available, consumed, and leftover moles.
- Optionally enter actual product mass to compute percent yield.
- Use the export buttons to download a CSV file or a PDF summary.
Frequently Asked Questions
1) What is a limiting reactant?
A limiting reactant is the substance that runs out first during a chemical reaction. It controls the maximum amount of product that can form because the reaction cannot continue once that reactant is completely consumed.
2) Why do I need a balanced equation?
A balanced equation provides the stoichiometric coefficients used to compare reactants fairly. Without correct coefficients, the calculator cannot determine how many complete reaction units each reactant can support.
3) Can I enter moles instead of grams?
Yes. Choose moles as the unit for any reactant. When you enter moles directly, the calculator skips the mass-to-mole conversion step and uses your value immediately.
4) When is molar mass required?
Molar mass is required only when your reactant amount is given in grams. The calculator uses molar mass to convert grams into moles before comparing stoichiometric reaction capacity.
5) What does reaction extent mean here?
Reaction extent in this calculator means the number of complete stoichiometric reaction units allowed by the limiting reactant. It helps determine how much of every reactant is consumed and how much product forms.
6) What is theoretical yield?
Theoretical yield is the maximum product amount predicted by stoichiometry when the limiting reactant is fully consumed. It assumes ideal completion with no side reactions, losses, or measurement errors.
7) How is percent yield calculated?
Percent yield compares the actual product mass from an experiment with the theoretical product mass from stoichiometry. The formula is actual yield divided by theoretical yield, then multiplied by 100.
8) Can this calculator handle three reactants?
Yes. You can enter up to three reactants in this version. The calculator converts each valid entry to reaction units, identifies the smallest value, and marks that reactant as limiting.