Calculator
Use coefficients from a balanced equation. This finds the theoretical amount of one selected species from a known species; identify the limiting reagent separately.
Formula and assumptions
n(target) = n(known) × coefficient(target) / coefficient(known)
Stoichiometric coefficients give the mole ratio in a balanced chemical equation. This tool does not identify a limiting reagent or account for yield.
Assumption: The supplied equation coefficients are balanced and the known reactant is available in the required amount.
Variables and units
Worked example
In 2H₂ + O₂ → 2H₂O, 2.00 mol H₂ corresponds to 2.00 mol H₂O.
Worked example: burning hydrogen
In 2H₂ + O₂ → 2H₂O the mole ratio of hydrogen to water is 2 : 2. Burning 4.00 g of hydrogen (1.984 mol at 2.016 g/mol) can give at most 1.984 mol of water, or 35.7 g. That needs 0.992 mol (31.7 g) of oxygen; with less oxygen than that, oxygen becomes the limiting reagent and sets the yield instead. Balance the equation before using its coefficients.
Important limits
It does not find a limiting reagent, model side reactions or apply an experimental yield.
Reference and related tools
OpenStax: Reaction stoichiometry. Return to Chemistry Calculators for the other tools in this group.