Theoretical Yield Calculator

Theoretical Yield Calculator

Theoretical Yield: 0 g

Percent Yield: 0%

function calculateYield() { var massReactant = parseFloat(document.getElementById('reactantMass').value); var mwReactant = parseFloat(document.getElementById('reactantMolarMass').value); var mwProduct = parseFloat(document.getElementById('productMolarMass').value); var coeffProduct = parseFloat(document.getElementById('ratioProduct').value); var coeffReactant = parseFloat(document.getElementById('ratioReactant').value); var actual = parseFloat(document.getElementById('actualYield').value); if (isNaN(massReactant) || isNaN(mwReactant) || isNaN(mwProduct) || isNaN(coeffProduct) || isNaN(coeffReactant) || mwReactant <= 0 || coeffReactant 0) { var percentYield = (actual / theoYield) * 100; document.getElementById('percResult').innerText = percentYield.toFixed(2); document.getElementById('percentWrapper').style.display = 'block'; } else { document.getElementById('percentWrapper').style.display = 'none'; } }

What is Theoretical Yield?

In chemistry, the theoretical yield represents the maximum amount of product that could be produced from a chemical reaction under perfect conditions. This calculation assumes that the reaction goes to completion, that all reactants are converted, and that no product is lost during the experimental process.

The Theoretical Yield Formula

To calculate the theoretical yield, you must identify the limiting reactant and use the following sequence of calculations:

1. Find Moles of Reactant: Mass (g) / Molar Mass (g/mol).
2. Use Stoichiometric Ratio: Moles of Reactant × (Coefficient of Product / Coefficient of Reactant).
3. Calculate Yield: Moles of Product × Molar Mass of Product.

Example Calculation

Imagine you react 10 grams of Sodium (Na) with excess Chlorine to produce Sodium Chloride (NaCl). The balanced equation is 2Na + Cl₂ → 2NaCl.

• Mass of Reactant: 10g Na
• Molar Mass Na: 22.99 g/mol
• Stoichiometry: 2 moles NaCl produced for every 2 moles Na consumed (1:1 ratio).
• Molar Mass NaCl: 58.44 g/mol

Step 1: 10g / 22.99 g/mol = 0.435 moles Na.

Step 2: 0.435 moles Na × (2/2) = 0.435 moles NaCl.

Step 3: 0.435 moles NaCl × 58.44 g/mol = 25.42g NaCl (Theoretical Yield).

Why Theoretical and Actual Yields Differ

In a real-world laboratory setting, the actual yield is almost always lower than the theoretical yield. This occurs due to several factors:

• Incomplete Reactions: Some reactions naturally reach equilibrium before all reactants are consumed.
• Side Reactions: Unintended reactions may occur, producing unwanted byproducts.
• Loss of Material: Filtering, pouring, or transferring substances often results in minor losses on glassware or filter paper.
• Impure Reactants: If the starting material is not 100% pure, the actual amount of reactant is lower than weighed.

The Percent Yield is calculated by dividing the Actual Yield by the Theoretical Yield and multiplying by 100. It serves as a measure of the efficiency of a synthetic process.