Chemical Reaction Calculator

Stoichiometry Calculator

Use this calculator to determine the mass of a product formed or a reactant needed, given the mass of another substance in a balanced chemical reaction. This tool simplifies stoichiometric calculations, which are fundamental in chemistry for predicting reaction yields and reactant requirements.

function calculateStoichiometry() { var reactantMass = parseFloat(document.getElementById("reactantMass").value); var reactantMolarMass = parseFloat(document.getElementById("reactantMolarMass").value); var reactantCoefficient = parseFloat(document.getElementById("reactantCoefficient").value); var productMolarMass = parseFloat(document.getElementById("productMolarMass").value); var productCoefficient = parseFloat(document.getElementById("productCoefficient").value); var resultDiv = document.getElementById("result"); if (isNaN(reactantMass) || isNaN(reactantMolarMass) || isNaN(reactantCoefficient) || isNaN(productMolarMass) || isNaN(productCoefficient) || reactantMass <= 0 || reactantMolarMass <= 0 || reactantCoefficient <= 0 || productMolarMass <= 0 || productCoefficient <= 0) { resultDiv.innerHTML = "Please enter valid positive numbers for all fields."; return; } // Step 1: Calculate moles of the known reactant var molesReactant = reactantMass / reactantMolarMass; // Step 2: Use stoichiometric ratio to find moles of the desired product // Moles of Product = (Moles of Reactant / Reactant Coefficient) * Product Coefficient var molesProduct = (molesReactant / reactantCoefficient) * productCoefficient; // Step 3: Calculate the mass of the desired product var massProduct = molesProduct * productMolarMass; resultDiv.innerHTML = "

Calculated Mass of Desired Product:

" + "" + massProduct.toFixed(4) + " grams" + "(Approximately " + molesProduct.toFixed(4) + " moles of product)"; }

Understanding Stoichiometry and Chemical Reactions

Stoichiometry is a branch of chemistry that deals with the quantitative relationships between reactants and products in chemical reactions. It is based on the law of conservation of mass, which states that matter cannot be created or destroyed in a chemical reaction. This means that the total mass of reactants must equal the total mass of products.

Balanced Chemical Equations

The foundation of any stoichiometric calculation is a balanced chemical equation. A balanced equation provides the molar ratios (stoichiometric coefficients) in which reactants combine and products are formed. For example, in the reaction:

2 H₂ + O₂ → 2 H₂O

This equation tells us that two moles of hydrogen gas (H₂) react with one mole of oxygen gas (O₂) to produce two moles of water (H₂O). The numbers in front of each chemical formula are the stoichiometric coefficients.

Molar Mass

Molar mass is the mass of one mole of a substance, typically expressed in grams per mole (g/mol). It is calculated by summing the atomic masses of all atoms in a chemical formula. For instance:

• Molar mass of H₂ = 2 × (atomic mass of H) ≈ 2 × 1.008 g/mol = 2.016 g/mol
• Molar mass of O₂ = 2 × (atomic mass of O) ≈ 2 × 16.00 g/mol = 32.00 g/mol
• Molar mass of H₂O = (2 × atomic mass of H) + (1 × atomic mass of O) ≈ (2 × 1.008) + 16.00 = 18.016 g/mol

How the Calculator Works (Step-by-Step)

This calculator performs the following steps to determine the mass of a desired product from a known reactant:

1. Convert Mass of Known Reactant to Moles: Using the provided mass and molar mass of the known reactant, the calculator first determines the number of moles of that reactant.
   Moles of Reactant = Mass of Reactant / Molar Mass of Reactant
2. Use Stoichiometric Ratio to Find Moles of Product: The balanced chemical equation provides the ratio between the moles of the known reactant and the moles of the desired product (their stoichiometric coefficients). The calculator uses this ratio to convert moles of reactant to moles of product.
   Moles of Product = (Moles of Reactant / Stoichiometric Coefficient of Reactant) × Stoichiometric Coefficient of Product
3. Convert Moles of Product to Mass: Finally, the calculator converts the moles of the desired product back into mass using its molar mass.
   Mass of Product = Moles of Product × Molar Mass of Product

Example Calculation: Water Production

Let's use the example of water formation: 2 H₂ + O₂ → 2 H₂O

Suppose you have 10 grams of Hydrogen gas (H₂) and you want to find out how much water (H₂O) can be produced.

• Mass of Known Reactant (H₂): 10 g
• Molar Mass of H₂: 2.016 g/mol
• Stoichiometric Coefficient of H₂: 2
• Molar Mass of H₂O: 18.015 g/mol
• Stoichiometric Coefficient of H₂O: 2

Using the calculator's logic:

1. Moles of H₂: 10 g / 2.016 g/mol ≈ 4.9603 mol H₂
2. Moles of H₂O: (4.9603 mol H₂ / 2) × 2 = 4.9603 mol H₂O
3. Mass of H₂O: 4.9603 mol × 18.015 g/mol ≈ 89.350 grams H₂O

This calculator helps you quickly perform these essential chemical calculations, saving time and reducing potential errors.