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Stoichiometry Calculator
Start with a complete chemical equation, choose a known amount and the species you want to calculate. The equation is balanced first, then the coefficient ratio is applied.
Enter reactants and products. If you only know the reactants, use Complete a reaction first.
2 mol O₂ can form 4 mol H₂O
Balance the equation first: 2 H₂ + O₂ → 2 H₂O. The coefficients show that 1 mol of O₂ corresponds to 2 mol of H₂O. With 2 mol of O₂, the target amount is therefore 4 mol of H₂O, provided enough H₂ is available.
From grams of H₂ to grams of H₂O
For the same reaction, 4.032 g of H₂ corresponds to about 2 mol of H₂. The coefficient ratio H₂:H₂O is 2:2, so the reaction can form about 2 mol of H₂O. Using the molar mass of water gives about 36.03 g of H₂O.
How the calculation works
Stoichiometric coefficients compare amounts in moles, not masses. When you enter grams, the calculator first converts the known mass to moles, applies the coefficient ratio, then converts the target amount to grams if requested.
This calculation assumes the stated reaction occurs as written and that the other reactants are available in sufficient quantity. To determine whether one reactant runs out first, use the limiting reactant calculator.