Calculate the percentage of each reactant consumed in a chemical reaction from initial and remaining masses. Identify the limiting reagent, compare conversions across reactants, and export results — all in your browser.
Reactant conversion (symbol $X$, also called fractional conversion) measures what fraction of a starting material is actually consumed during a reaction. A conversion of 100% means all of the reactant was used up; a conversion of 50% means half remained unreacted. Unlike % yield — which compares isolated product to theoretical maximum — conversion focuses directly on the reactant side: how much of what you put in was transformed?
| Symbol | Term | Units |
|---|---|---|
| $X_A$ | Conversion of reactant A | % (dimensionless × 100) |
| $n_{A,0}$ | Initial moles of reactant A | mol |
| $n_A$ | Moles of reactant A remaining at the end | mol |
Because moles = mass ÷ MW, and the MW of a compound is constant, the MW cancels in the ratio — so conversion can be calculated equally from masses: $X_A = (m_{A,0} - m_A)\,/\,m_{A,0} \times 100\%$. This tool uses masses as inputs and MW to display moles.
| Reaction type | Typical conversion | Key factor |
|---|---|---|
| Irreversible reactions (excess reagent, excess time) | ~100% | Thermodynamically driven to completion |
| SN2 substitution (stoichiometric conditions) | 80–99% | Depends on leaving group, nucleophile strength |
| Reversible reactions (e.g. Fischer esterification) | 50–70% | Limited by equilibrium; product removal improves it |
| Catalytic reactions (incomplete catalyst loading) | 40–80% | Catalyst turnover frequency and loading |
| Metric | What it measures | Stage |
|---|---|---|
| Reactant Conversion (X) | Fraction of each reactant consumed during reaction | Experimental |
| % Yield | Fraction of theoretical maximum product actually isolated | Experimental |
| Atom Economy (AE) | Theoretical fraction of reactant mass incorporated into desired product | Design |
| RME (Reaction Mass Efficiency) | AE × yield × stoichiometric factor — combined practical efficiency | Both |
| E-factor | Mass of all waste per mass of product (includes solvents, workup) | Experimental |
Enter each reactant with its molecular weight, initial mass, and the mass remaining after the reaction (unreacted starting material recovered). The tool calculates conversion for each reactant and identifies the limiting reagent as the one with the lowest initial moles. Leave MW blank to calculate conversion from mass alone.
| Reactant name | Formula | MW (g/mol) | Initial mass (g) | Remaining (g) | Conversion (%) |
|---|
| Reactant | Initial (g) | Remaining (g) | Consumed (g) | Initial (mol) | Conversion (%) | Role | Visual |
|---|---|---|---|---|---|---|---|
| Enter reactant data above to see breakdown. | |||||||
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Export your reactant conversion calculation as a PDF report or CSV data file. PDF opens in a new tab and uses your browser's print function. CSV downloads directly.
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© 2024– DodecaGreen Project. All rights reserved. · Last updated: 09/06/2026
This portal was built with the assistance of a large language model (Claude, Anthropic), which was used to generate and refine code, articulate and structure contributed ideas within the defined page format, and support iterative design decisions. All scientific content, conceptual frameworks, pedagogical choices, and final outputs were directed, reviewed, and verified by the contributors listed above.
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