Chemistry Reaction Calculator

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Chemistry Stoichiometry & Theoretical Yield Calculator

Reactant (A)

Product (B)

Calculation Results

function calculateReaction() { var massA = parseFloat(document.getElementById('massA').value); var mmA = parseFloat(document.getElementById('molarMassA').value); var cA = parseFloat(document.getElementById('coeffA').value); var mmB = parseFloat(document.getElementById('molarMassB').value); var cB = parseFloat(document.getElementById('coeffB').value); var actual = parseFloat(document.getElementById('actualYield').value); var resDiv = document.getElementById('chemResult'); var output = document.getElementById('resultOutput'); if (isNaN(massA) || isNaN(mmA) || isNaN(cA) || isNaN(mmB) || isNaN(cB) || mmA <= 0 || mmB <= 0 || cA <= 0 || cB <= 0) { alert("Please enter valid positive numbers for all required chemical parameters."); return; } // 1. Calculate Moles of A var molesA = massA / mmA; // 2. Use Stoichiometry to find Moles of B // (moles A / coeff A) = (moles B / coeff B) var molesB = (molesA * cB) / cA; // 3. Calculate Theoretical Yield of B var theoreticalYield = molesB * mmB; var html = "Moles of Reactant A: " + molesA.toFixed(4) + " mol"; html += "Expected Moles of Product B: " + molesB.toFixed(4) + " mol"; html += "Theoretical Yield: " + theoreticalYield.toFixed(2) + " grams"; if (!isNaN(actual) && actual >= 0) { var percentYield = (actual / theoreticalYield) * 100; var color = percentYield > 90 ? "#2ecc71" : (percentYield > 50 ? "#f39c12" : "#e74c3c"); html += "Percent Yield: " + percentYield.toFixed(2) + "%"; } output.innerHTML = html; resDiv.style.display = 'block'; }

Mastering Chemical Stoichiometry: The Reaction Calculator Guide

Understanding the relationship between reactants and products in a chemical reaction is fundamental to laboratory work and industrial chemistry. A Chemistry Reaction Calculator simplifies the complex task of determining how much product you can expect from a specific amount of starting material.

What is Stoichiometry?

Stoichiometry is the section of chemistry that involves using relationships between reactants and/or products in a chemical reaction to determine desired quantitative data. In Greek, stoicheion means element and metron means measure. Essentially, it is the "recipe" for a chemical reaction.

How to Calculate Theoretical Yield

To calculate the theoretical yield manually, follow these four essential steps:

  1. Balance the Equation: Ensure the number of atoms for each element is the same on both sides.
  2. Convert Mass to Moles: Divide the mass of your reactant by its molar mass (g/mol).
  3. Use the Mole Ratio: Use the coefficients from the balanced equation to find the moles of the desired product.
  4. Convert Moles back to Mass: Multiply the moles of the product by its specific molar mass.

Example Calculation

Suppose you are reacting 10 grams of Methane (CH₄) with excess oxygen to produce Carbon Dioxide (CO₂).

  • Reaction: CH₄ + 2O₂ → CO₂ + 2H₂O
  • Reactant A (CH₄): Mass = 10g, Molar Mass = 16.04 g/mol, Coefficient = 1
  • Product B (CO₂): Molar Mass = 44.01 g/mol, Coefficient = 1

Using the calculator, you would find that 10g of CH₄ produces a theoretical yield of approximately 27.44 grams of CO₂.

Understanding Percent Yield

In a perfect world, chemical reactions would produce exactly what the math predicts. However, in reality, factors like incomplete reactions, loss during filtration, or side reactions often lead to a lower "Actual Yield."

The formula for Percent Yield is:

(Actual Yield / Theoretical Yield) x 100 = Percent Yield

A high percent yield (90%+) indicates a very efficient reaction, while a low percent yield suggests that the experimental process may need optimization.

Key Terms for Chemistry Calculations

Term Definition
Molar Mass The mass of one mole of a substance (g/mol).
Coefficient The number in front of a formula in a balanced equation.
Limiting Reactant The substance that is totally consumed when the chemical reaction is complete.
Mole A unit of measurement (6.022 x 10²³) for amount of substance.

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