Theoretical Yield Calculator

Theoretical yield is the maximum mass of product that can be obtained if the reaction goes to 100% completion. It is calculated from the limiting reagent using mole ratios and molar masses.

📊 Stoichiometry📐 Theoretical Yield⚗️ Reactions

Mass of limiting reagent (g)

Molar mass of limiting reagent (g/mol)

Coefficient of limiting reagent

Coefficient of product

Molar mass of product (g/mol)

Please enter valid values.

Formula & Reference

Variable	Symbol	Formula	Units
Theoretical Yield	m_th	n_limiting × (coeff_product/coeff_limiting) × M_product	g
Limiting Moles	n_lim	m/M of limiting reagent	mol
Mole Ratio	—	Coefficient product / Coefficient limiting	—

Step-by-Step Examples

Example 1

Ammonia from N₂

N₂ + 3H₂ → 2NH₃. 28.0 g N₂ (M=28.02), limiting. Coeff N₂=1, NH₃=2, M(NH₃)=17.03.

mol N₂ = 28.0/28.02 = 0.999 mol
mol NH₃ = 0.999×2 = 1.998 mol
mass NH₃ = 1.998×17.03 = 34.02 g

✓ Theoretical yield = 34.0 g NH₃

Example 2

Water from H₂

2H₂ + O₂ → 2H₂O. 4.00 g H₂ (M=2.016) is limiting.

mol H₂ = 4.00/2.016 = 1.984 mol
mol H₂O = 1.984×(2/2) = 1.984 mol
mass H₂O = 1.984×18.02 = 35.74 g

✓ Theoretical yield = 35.7 g H₂O

Example 3

Aspirin Synthesis

Salicylic acid + acetic anhydride → aspirin. 5.00 g salicylic acid (M=138.12), coeff=1, aspirin coeff=1, M=180.16.

mol SA = 5.00/138.12 = 0.03620 mol
mol aspirin = 0.03620×1 = 0.03620 mol
mass = 0.03620×180.16 = 6.52 g

✓ Theoretical yield = 6.52 g aspirin

Real-World Applications

🧪

Reaction Planning

Chemists calculate theoretical yield before starting to know what to expect.

📊

Yield Comparison

Actual yield vs theoretical yield gives percent yield for performance assessment.

🏭

Scale-Up

Scaling reactions from grams to kilograms uses the same theoretical yield calculation.

💊

Drug Synthesis

Pharmaceutical companies optimize steps to maximize theoretical and actual yields.

Common Mistakes to Avoid

⚠️

Using wrong limiting reagent

First identify the limiting reagent (smallest n/coeff ratio). Theoretical yield is ALWAYS based on the limiting reagent.

⚠️

Forgetting mole ratio

Multiply moles of limiting reagent by (coeff product / coeff limiting). Not 1:1 unless coefficients are equal.

⚠️

Wrong molar mass for product

Use the product molar mass, not the reactant. Calculate carefully from the product formula.

Frequently Asked Questions

How is theoretical yield different from actual yield? ▾

Theoretical is calculated from stoichiometry (100% conversion). Actual is what you physically collect. Actual ≤ theoretical always.

What limits theoretical yield? ▾

Stoichiometry. Even at 100% yield, you cannot get more product than the limiting reagent allows by mole ratio.

Can theoretical yield be greater than limiting reagent mass? ▾

Yes. If product MW > limiting reagent MW, more product mass can form. e.g., 28 g N₂ gives up to 34 g NH₃.

What is overall yield in multi-step synthesis? ▾

Multiply percent yields: 3 steps at 90% each gives 0.9×0.9×0.9 = 72.9% overall. Each step theoretical yield feeds the next.

How do I find theoretical yield in grams? ▾

Convert limiting reagent mass to moles, multiply by mole ratio, multiply by product molar mass.

Related Chemistry Calculators

Formula Explorer connections

Interpretation: This relationship converts chemical amount, mass, composition or balanced-equation ratios into a reaction quantity. Assumption: Use a balanced reaction, consistent units and the correct molar mass. Purity, side reactions and limiting reagents can change experimental results.

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