Stoichiometry Calculator
Use this calculator to determine the mass of a reactant or product needed or produced in a chemical reaction, given the balanced chemical equation and the mass of one substance. This tool helps you apply stoichiometric principles to real-world chemical problems.
Result:
Understanding Stoichiometry and Mass Balance
Stoichiometry is a branch of chemistry that deals with the quantitative relationships between reactants and products in a chemical reaction. 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 the reactants must equal the total mass of the products.
The Mole Concept and Balanced Equations
At the heart of stoichiometry is the mole concept. A mole represents a specific number of particles (Avogadro's number, approximately 6.022 x 1023). Chemical equations must be balanced to accurately represent the mole ratios of reactants and products. The coefficients in a balanced chemical equation indicate the relative number of moles of each substance involved in the reaction.
For example, in the reaction for the formation of water:
2H₂(g) + O₂(g) → 2H₂O(l)
This balanced equation tells us that 2 moles of hydrogen gas react with 1 mole of oxygen gas to produce 2 moles of water. These mole ratios are crucial for stoichiometric calculations.
How to Use the Stoichiometry Calculator
- Identify the Balanced Equation: Ensure you have a correctly balanced chemical equation for your reaction.
- Identify Known and Target Substances: Determine which substance you have a known mass for (Known Substance) and which substance you want to calculate the mass of (Target Substance).
- Enter Coefficients: Input the stoichiometric coefficients for both the Known and Target Substances from your balanced equation.
- Enter Molar Masses: Provide the molar mass (in g/mol) for both the Known and Target Substances. You can typically find molar masses from the periodic table by summing the atomic masses of all atoms in the chemical formula.
- Enter Known Mass: Input the mass (in grams) of the Known Substance you have.
- Calculate: Click the "Calculate Mass" button to get the mass of the Target Substance.
Example Calculation:
Let's use the water formation example: 2H₂(g) + O₂(g) → 2H₂O(l)
Suppose you have 10 grams of hydrogen gas (H₂) and you want to find out how much oxygen gas (O₂) is needed to react completely with it.
- Known Substance: H₂
- Target Substance: O₂
- Coefficient of Known Substance (H₂): 2
- Molar Mass of Known Substance (H₂): 2.016 g/mol
- Mass of Known Substance (H₂): 10 g
- Coefficient of Target Substance (O₂): 1
- Molar Mass of Target Substance (O₂): 32.00 g/mol
Using the calculator with these values will show that approximately 79.36 grams of O₂ are needed.
The calculation steps are:
- Convert mass of Known Substance to moles:
Moles H₂ = 10 g / 2.016 g/mol = 4.960 mol H₂ - Use mole ratio to find moles of Target Substance:
Moles O₂ = 4.960 mol H₂ * (1 mol O₂ / 2 mol H₂) = 2.480 mol O₂ - Convert moles of Target Substance to mass:
Mass O₂ = 2.480 mol O₂ * 32.00 g/mol = 79.36 g O₂
This calculator simplifies these steps, allowing you to quickly perform stoichiometric calculations for various chemical reactions.