Percent Yield Calculator
Calculate the percent yield of any chemical reaction using the formula (actual yield / theoretical yield) × 100. Essential for evaluating reaction efficiency, identifying losses, and optimizing lab procedures. Supports mass units in grams, milligrams, or kilograms.
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Understanding Percent Yield in Chemical Reactions
Percent yield measures how close your experimental result is to the theoretical maximum. It is calculated as: Percent Yield = (Actual Yield / Theoretical Yield) × 100%. Actual yield is the amount of product you actually obtain from a reaction; theoretical yield is the amount you would obtain if the reaction went perfectly (no losses, side reactions, or incomplete conversion). A high percent yield indicates efficient reaction conditions, while low yield points to problems like purification losses or incomplete reaction. This calculator also computes the yield loss (the difference between theoretical and actual yield). Both actual and theoretical yields can be entered in grams, milligrams, or kilograms, and the calculator automatically converts them to grams before calculation.
Formula
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How to Use?
- Enter the actual yield you obtained from your experiment.
- Enter the theoretical yield (calculated from stoichiometry).
- Select the appropriate units for each (g, mg, kg) – they can be different; the calculator will convert both to grams.
- The result shows the percent yield and the absolute yield loss (the amount of product you didn’t recover).
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Worked Examples
Percent yield for a synthesis with 5.2 g actual vs. 6.0 g theoretical
Percent yield with different units (mg and g)
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Why Percent Yield Matters
Percent yield is a key indicator of reaction efficiency. A yield close to 100% means your procedure is well‑optimized, while lower yields may point to incomplete reactions, loss during purification, or measurement errors.
Calculating Theoretical Yield
Theoretical yield is found from the limiting reagent using stoichiometry. For example, if you start with 1 mole of reactant that yields 1 mole of product, and the product has a molar mass of 100 g/mol, the theoretical yield is 100 g. This calculator does not compute theoretical yield – you must enter it separately.
Minimizing Yield Loss
Yield loss = theoretical yield – actual yield. Understanding where losses occur (e.g., during filtration, crystallization, or transfer) can help improve your experimental technique and increase percent yield.
Table: Interpretation of Percent Yield
| Percent Yield | Interpretation |
|---|---|
| ≥ 90% | Excellent – high efficiency |
| 70 – 89% | Good – typical for many reactions |
| 50 – 69% | Fair – possible losses or side reactions |
| < 50% | Poor – significant issues |
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FAQs
What is a good percent yield?
In academic settings, yields above 80% are often considered good, but this varies by reaction. Some reactions naturally have low yields; always compare to literature values for your specific reaction.
Why is my percent yield above 100%?
A yield >100% usually indicates the product is contaminated (with solvent, impurities, or water) or the theoretical yield was underestimated. Ensure both yields are measured correctly and the product is pure.
Can I use this for yield in other units (like moles)?
This calculator is designed for mass yields. For mole‑based yields, you would need to convert to mass first, or use our molar mass calculator to get the mass from moles.
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