Chemical Equation Calculator

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Stoichiometry Mass-to-Mass Calculator

Use this calculator to determine the theoretical mass of a product that can be formed from a given mass of a reactant, based on a balanced chemical equation. This calculator performs mass-to-mass stoichiometry calculations.

Calculation Result:

function calculateStoichiometry() { var reactantACoeff = parseFloat(document.getElementById('reactantACoeff').value); var reactantAMolarMass = parseFloat(document.getElementById('reactantAMolarMass').value); var reactantAMass = parseFloat(document.getElementById('reactantAMass').value); var productBCoeff = parseFloat(document.getElementById('productBCoeff').value); var productBMolarMass = parseFloat(document.getElementById('productBMolarMass').value); var resultDiv = document.getElementById('stoichiometryResult'); if (isNaN(reactantACoeff) || isNaN(reactantAMolarMass) || isNaN(reactantAMass) || isNaN(productBCoeff) || isNaN(productBMolarMass) || reactantACoeff <= 0 || reactantAMolarMass <= 0 || reactantAMass <= 0 || productBCoeff <= 0 || productBMolarMass <= 0) { resultDiv.innerHTML = 'Please enter valid positive numbers for all fields.'; return; } // Step 1: Calculate moles of Reactant A var molesA = reactantAMass / reactantAMolarMass; // Step 2: Use mole ratio to find moles of Product B // molesB = molesA * (coeffB / coeffA) var molesB = molesA * (productBCoeff / reactantACoeff); // Step 3: Calculate mass of Product B var massB = molesB * productBMolarMass; resultDiv.innerHTML = 'Moles of Reactant A: ' + molesA.toFixed(4) + ' mol' + 'Theoretical Moles of Product B: ' + molesB.toFixed(4) + ' mol' + 'Theoretical Mass of Product B: ' + massB.toFixed(4) + ' g'; }

Understanding Stoichiometry and Mass-to-Mass Calculations

Stoichiometry is a branch of chemistry that deals with the quantitative relationships between reactants and products in chemical reactions. It allows chemists to predict the amount of product that can be formed from a given amount of reactant, or vice versa, based on the law of conservation of mass.

The Balanced Chemical Equation: Your Recipe

At the heart of stoichiometry is the balanced chemical equation. This equation acts like a recipe, showing the exact whole-number ratio of moles of reactants consumed and products formed. For example, the reaction for the formation of water:

2 H₂ + O₂ → 2 H₂O

This equation tells us that 2 moles of hydrogen gas (H₂) react with 1 mole of oxygen gas (O₂) to produce 2 moles of water (H₂O).

Mass-to-Mass Calculations: From Grams to Grams

Often, in a laboratory setting, we measure substances by mass (grams) rather than by moles. Mass-to-mass stoichiometry calculations allow us to convert a given mass of one substance in a reaction to the theoretical mass of another substance (reactant or product). The process typically involves three main steps:

  1. Convert Mass of Given Substance to Moles: Using the molar mass of the given substance, convert its mass (in grams) into moles.
  2. Convert Moles of Given Substance to Moles of Desired Substance: Using the mole ratio from the balanced chemical equation, convert the moles of the given substance to moles of the desired substance.
  3. Convert Moles of Desired Substance to Mass: Using the molar mass of the desired substance, convert its moles back into mass (in grams).

Formula Used in This Calculator:

Let's say you have a balanced reaction: aA + bB → cC + dD

Where 'a', 'b', 'c', 'd' are the stoichiometric coefficients, and A, B, C, D are the chemical species.

To find the theoretical mass of Product C from a given mass of Reactant A:

  1. Moles of A = Mass of A / Molar Mass of A
  2. Moles of C = Moles of A × (Coefficient of C / Coefficient of A)
  3. Mass of C = Moles of C × Molar Mass of C

Example: Water Formation

Consider the reaction: 2 H₂ + O₂ → 2 H₂O

If you start with 10.0 grams of Hydrogen (H₂), how much water (H₂O) can theoretically be produced?

  • Reactant A: H₂
  • Product B: H₂O
  • Coefficient of H₂ (a): 2
  • Molar Mass of H₂: Approximately 2.016 g/mol
  • Mass of H₂: 10.0 g
  • Coefficient of H₂O (c): 2
  • Molar Mass of H₂O: Approximately 18.015 g/mol

Using the calculator with these values:

  1. Moles of H₂: 10.0 g / 2.016 g/mol = 4.9603 mol H₂
  2. Moles of H₂O: 4.9603 mol H₂ × (2 mol H₂O / 2 mol H₂) = 4.9603 mol H₂O
  3. Mass of H₂O: 4.9603 mol H₂O × 18.015 g/mol = 89.36 g H₂O

Therefore, 10.0 grams of hydrogen can theoretically produce approximately 89.36 grams of water.

This calculator simplifies these steps, allowing you to quickly perform mass-to-mass conversions for any balanced chemical reaction.

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