Stoichiometry Input Form
Enter a balanced reaction manually. The calculator uses your coefficients exactly as provided.
Example Data Table
Example reaction: 2H₂ + O₂ → 2H₂O
| Species | Type | Coefficient | Molar Mass (g/mol) | Sample Amount | Unit | Purity % |
|---|---|---|---|---|---|---|
| H2 | Reactant | 2 | 2.016 | 10 | g | 100 |
| O2 | Reactant | 1 | 31.998 | 80 | g | 100 |
| H2O | Product | 2 | 18.015 | Optional actual yield input | g | — |
Formula Used
Core Stoichiometry Equations
Available moles = unit-converted amount ÷ molar mass, when mass is entered.
Effective moles = available moles × purity ÷ 100.
Reaction extent = minimum of effective moles ÷ coefficient.
Required reactant moles = reaction extent × reactant coefficient.
Output Equations
Theoretical product moles = reaction extent × product coefficient.
Theoretical mass = product moles × molar mass.
Particles = moles × 6.02214076 × 1023.
Percent yield = actual product moles ÷ theoretical product moles × 100.
How to Use This Calculator
- Enter a reaction title for your own reference.
- Fill in balanced coefficients for each reactant and product.
- Provide molar masses for all entered substances.
- Enter at least one reactant quantity and choose its unit.
- Add purity values when materials are not fully pure.
- Select a target product if you want percent yield.
- Optionally enter actual product amount for yield comparison.
- Click the calculate button to see tables, ratios, and chart.
- Download the results as CSV or PDF after calculation.
Key Questions Answered
How is stoichiometry used to calculate amounts of substances in a chemical reaction?
Stoichiometry uses balanced coefficients to convert one substance amount into another. After converting the known quantity into moles, coefficient ratios predict required reactants, theoretical products, leftovers, and yield for the same reaction scale.
How do you calculate chemical reaction stoichiometry (crs)?
Write a balanced equation, convert the known amount into moles, divide by its coefficient, and compare all available reactants. The smallest ratio gives the limiting reagent and reaction extent. Then multiply that extent by other coefficients to find amounts.
FAQs
1. What is a limiting reagent?
The limiting reagent is the reactant that runs out first. It fixes the maximum reaction extent and controls the greatest possible product amount. All theoretical outputs come from that limiting value.
2. Why must the chemical equation be balanced first?
A balanced equation provides the correct mole ratios between species. Without balanced coefficients, the calculator cannot convert reactants to products accurately, and limiting reagent results would be wrong.
3. Can I enter grams instead of moles?
Yes. The calculator accepts grams, kilograms, milligrams, moles, millimoles, micromoles, and particles. Mass values are converted to moles using the molar mass you enter for each species.
4. What does purity change in the calculation?
Purity adjusts the usable amount of reactant. A 90% pure sample contributes only 90% of its converted moles to the reaction. That correction can change the limiting reagent and product output.
5. How is percent yield determined?
Percent yield compares actual product to theoretical product. Convert the actual product amount into moles, divide by the theoretical moles for the selected product, and multiply by 100.
6. What are excess reactants?
Excess reactants remain after the limiting reagent is fully consumed. The calculator shows both excess moles and excess mass, helping you estimate leftovers and improve process planning.
7. When should particles be used as an input unit?
Use particles when the amount is given as molecules, atoms, or formula units. The calculator converts particles into moles using Avogadro’s constant before applying stoichiometric ratios.
8. Does this calculator balance the reaction automatically?
No. You enter the balanced coefficients yourself. This design keeps the calculation transparent and flexible, especially for classroom work, laboratory checks, and process troubleshooting.