Calculator input
Enter a balanced equation. Use formulas exactly as they appear in the equation, such as H2, O2, or H2O.
How to use this calculator
- Type a balanced reaction using an arrow, such as 2H2 + O2 -> 2H2O.
- Enter the known compound formula exactly as it appears in the equation.
- Add the known mass in grams and adjust purity when needed.
- Enter the target compound formula for the product or reagent you want to calculate.
- Add an actual product mass when you want measured percent yield.
- Use the inventory box to compare multiple reactant masses.
- Press calculate, then review the result, table, and chart.
- Use CSV or PDF buttons to save a copy of the result.
Example data table
| Equation |
Known formula |
Known mass |
Target |
Expected output |
| 2H2 + O2 -> 2H2O |
H2 |
4 g |
H2O |
About 35.75 g water |
| CaCO3 -> CaO + CO2 |
CaCO3 |
100 g |
CO2 |
About 43.97 g carbon dioxide |
| N2 + 3H2 -> 2NH3 |
N2 |
28 g |
NH3 |
About 34.03 g ammonia |
Mass calculations for chemical equations
Why mass matters
Mass is the easiest laboratory value to measure. A reaction equation shows mole ratios. This calculator joins both ideas. It turns coefficients into practical gram amounts. That helps students, teachers, and lab teams prepare safer quantities. It also reduces repeated hand calculation.
Balanced equation first
A balanced equation is the foundation. Each element must have the same atom count on both sides. The tool checks that count and warns when the equation may be wrong. A wrong equation gives wrong mass ratios. Always fix the reaction before using the final result.
Mole ratio workflow
The workflow starts with molar mass. The known mass is corrected for purity. Then it is converted into moles. The mole amount is divided by the compound coefficient. This gives reaction extent. Every product and reactant can then be scaled from that same extent.
Yield and purity
Real reactions rarely produce perfect output. Side reactions, transfer loss, wet samples, and impure reagents change final mass. The yield field estimates practical product mass. The actual mass field compares a measured result with the theoretical result. The purity field corrects the available active material.
Planning with inventory
The inventory box is useful when more than one reactant is available. Add each reactant mass on a separate line. The calculator converts every listed reactant into possible reaction extent. The smallest extent marks the limiting reactant. Extra pure mass is also estimated.
Using exported results
CSV export is useful for spreadsheets. PDF export is useful for lab notes and reports. The chart gives a quick comparison of masses across the reaction. These outputs make the calculation easier to review, store, and share.
FAQs
1. Does this calculator balance equations?
It checks atom balance, but it does not automatically balance every reaction. Enter a balanced equation for best mass accuracy.
2. Which arrow can I use?
You can use ->, =, or common arrow symbols. The page converts them into a standard reaction format internally.
3. Can I enter hydrates?
Yes. Hydrates such as CuSO4·5H2O are supported. A normal dot can also work when your keyboard lacks the hydrate dot.
4. What is active mass?
Active mass is the usable chemical mass after purity correction. It equals gross mass multiplied by the purity percentage.
5. What does reaction extent mean?
Reaction extent is the scaled mole amount for one complete coefficient set. It lets every term in the equation be calculated consistently.
6. How is limiting reactant found?
Each reactant inventory mass is converted to moles and divided by its coefficient. The smallest value is the limiting reactant.
7. Why is my product mass unexpected?
Check the equation balance, formula spelling, coefficient values, purity percentage, and target formula. Small formula errors can change molar mass.
8. Can I use this for homework?
Yes. It shows formulas, mole ratios, and tables. Still, write the steps required by your teacher or syllabus.