Example Data Table
| Balanced equation |
Known |
Target |
Given |
Ratio |
Answer |
| 2H2 + O2 → 2H2O |
H2 |
H2O |
4 g H2 |
2:2 |
35.72 g H2O |
| N2 + 3H2 → 2NH3 |
N2 |
NH3 |
28 g N2 |
1:2 |
34.06 g NH3 |
| CaCO3 → CaO + CO2 |
CaCO3 |
CO2 |
100 g CaCO3 |
1:1 |
44.01 g CO2 |
Formula Used
Moles from mass: moles = mass ÷ molar mass.
Mole ratio: target moles = known moles × target coefficient ÷ known coefficient.
Mass from moles: mass = moles × molar mass.
Particles: particles = moles × 6.02214076 × 10²³.
Gas at STP: volume = moles × 22.414 liters.
Ideal gas law: PV = nRT, so volume = nRT ÷ P.
Solution stoichiometry: moles = molarity × volume in liters.
Yield adjustment: expected output = theoretical output × yield percent ÷ 100.
How to Use This Calculator
Enter the balanced chemical equation for reference. Then enter the known compound and the product or reactant you want to calculate. Add the coefficients exactly as they appear in the balanced equation.
Choose the known amount type. You can use mass, moles, particles, gas volume, or solution volume. For solutions, enter molarity and liters. For custom gas volume, enter pressure and temperature.
Select the target output type. Add purity, yield, or observed output when needed. Use the optional second reactant area to check limiting reagent behavior.
Stoichiometry With Steps
Why Stoichiometry Matters
Stoichiometry links a balanced chemical equation to real measured quantities. It turns symbols into grams, moles, particles, gas volumes, and solution volumes. The method is useful in class work, lab planning, manufacturing, and quality checks. A correct stoichiometry answer starts with a balanced equation. The coefficients in that equation show the mole relationship between substances.
Mole Ratio Logic
The calculator first converts the given amount into moles. This is the central step. Mass is divided by molar mass. Particles are divided by Avogadro’s number. Gas volume can use standard molar volume or the ideal gas law. Solution volume is converted with molarity. After that, the known moles are compared with the balanced coefficient.
Limiting Reactant Use
Many reactions use more than one reactant. One reactant may run out first. That reactant is the limiting reagent. This page can compare a second reactant by dividing each reactant’s moles by its coefficient. The smaller value controls the reaction. The target amount is then based on that limiting value.
Yield and Purity
Real experiments are rarely perfect. A reagent may be impure. A reaction may lose product during heating, filtering, transfer, or drying. The purity setting corrects the usable starting amount. The yield setting estimates practical output from the theoretical amount. You can also enter observed output to calculate an actual yield percent.
Clear Step Review
Each result includes the main conversion steps. This helps students find mistakes quickly. It also helps teachers review the reasoning. Check formulas, coefficients, units, and molar masses before using the final result in a report.
FAQs
1. What is stoichiometry?
Stoichiometry is the calculation of reactant and product amounts from a balanced chemical equation. It uses mole ratios from equation coefficients.
2. Why must the equation be balanced?
A balanced equation gives correct mole ratios. Without balanced coefficients, the calculated reactant or product amount will be wrong.
3. Can this calculator find a limiting reagent?
Yes. Enter a second reactant formula, coefficient, and amount. The calculator compares mole-per-coefficient values and selects the smaller one.
4. What does purity percent mean?
Purity percent adjusts the usable amount of the known substance. For example, 90% purity means only 90% reacts as the chosen formula.
5. What is theoretical yield?
Theoretical yield is the maximum product amount predicted by stoichiometry. It assumes complete reaction and no material loss.
6. How is actual yield percent calculated?
Observed output is converted to moles. Then it is divided by theoretical target moles and multiplied by 100.
7. Can I use hydrate formulas?
Yes. The formula parser supports hydrate dots, such as CuSO4·5H2O, and grouped formulas, such as Al2(SO4)3.
8. Does it support gas calculations?
Yes. You can use gas volume at STP or custom gas volume with pressure and temperature through the ideal gas law.