Chemical Reaction Yield Calculator
Enter masses, molar masses, and coefficients to see the theoretical and percent yield.
| Limiting reagent moles | — |
|---|---|
| Theoretical product mass | — |
| Actual product mass | — |
| Percent yield | — |
Why Yield Matters
Chemists often compare theoretical yield, actual yield, and percent yield. The theoretical yield represents the maximum amount of product possible if everything reacts perfectly. In practice, side reactions, incomplete conversions, and transfer losses reduce the quantity collected. Percent yield is the ratio of actual product to the theoretical limit. Knowing these values helps you evaluate the efficiency of a reaction and troubleshoot lab problems.
From Mass to Moles
Most reaction equations are written in terms of moles. The first step converts the mass of your limiting reagent to moles using
Here, is the amount of substance in moles, is the mass in grams, and is the molar mass in grams per mole. Once you know the moles of limiting reagent, you can use the balanced coefficients to determine how many moles of product can form.
Using Stoichiometric Ratios
Suppose your balanced equation shows moles of limiting reagent produce moles of product. The theoretical moles of product are given by
Multiplying by the product's molar mass yields the theoretical product mass. Comparing this with your actual collected mass reveals the percent yield.
Worked Scenarios
The table below demonstrates how different stoichiometries translate to percent yield outcomes.
| Reaction | Theoretical mass (g) | Actual mass (g) | Percent yield |
|---|---|---|---|
| 1 A → 1 B | 12.0 | 8.0 | 67% |
| 2 A → 3 B | 18.5 | 15.7 | 85% |
| 1 A + 2 C → 1 D | 9.3 | 6.0 | 65% |
Beyond the Calculation
Yields rarely reach one hundred percent. Some reagents may not fully dissolve, or competing reactions might form unwanted by-products. Transfers between containers can leave residue behind. If the reaction is reversible, equilibrium may limit conversion. Measuring yield across repeated trials helps confirm whether a procedure is reliable and where efficiency can improve.
Manual calculations require careful unit conversions and are prone to error, especially when coefficients are not one-to-one. This calculator keeps everything client-side, eliminating the need for a spreadsheet. For deeper experimentation, explore the molarity-calculator, molar-mass-calculator, and pcr-reaction-mix-calculator to prepare reagents and reaction mixtures with consistent precision.