Stoichiometry Calculator

Calculate the mass of a desired substance given a balanced chemical equation and the mass of another substance.

Result: Mass of Desired Substance

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How to Calculate Stoichiometry

Stoichiometry is the quantitative study of the relationships among reactants and products in a chemical reaction. The calculation allows you to determine the amount of a substance that is consumed or produced in a reaction, given the amount of another substance.

The process involves three main steps:

  1. Convert Mass to Moles:

    Using the molar mass of the given substance, convert its mass into moles.

    Moles = Mass / Molar Mass

  2. Use the Molar Ratio:

    Using the stoichiometric coefficients from the balanced chemical equation, find the moles of the desired substance.

    Moles of Desired = Moles of Given * (Coefficient of Desired / Coefficient of Given)

  3. Convert Moles to Mass:

    Convert the moles of the desired substance into mass using its molar mass.

    Mass = Moles * Molar Mass

Example Calculation

Consider the reaction: 2H₂O → 2H₂ + O₂. If we start with 50g of water (H₂O) and want to find out how much oxygen (O₂) is produced:

  1. Moles of H₂O = 50 g / 18.015 g/mol ≈ 2.775 moles
  2. Moles of O₂ = 2.775 moles H₂O * (1 mole O₂ / 2 moles H₂O) = 1.3875 moles O₂
  3. Mass of O₂ = 1.3875 moles * 32.00 g/mol ≈ 44.4 g

Quick FAQs

What is a balanced equation?
A balanced equation has the same number of atoms of each element on both sides of the reaction, satisfying the Law of Conservation of Mass.
What is a stoichiometric coefficient?
It's the number in front of a chemical formula in a balanced equation, indicating the relative number of moles involved.
Why are my results slightly different?
Rounding molar masses during intermediate steps can lead to small discrepancies. It is best to use precise molar masses and round only the final answer.