Limiting Reagent
The reactant that is completely consumed first and therefore determines the maximum amount of product obtainable.
Formula / equation
smallest n / coefficient
Unit
mol
In depth
It is identified by dividing each reactant's number of moles by its coefficient; the smallest quotient marks the limiting species. Once it runs out the reaction stops, however much of the other reactants remains. Every theoretical yield calculation must be based on the limiting reagent.
Examples in the real world
With 3 mol H₂ and 3 mol N₂, hydrogen limits the Haber process because 3 ÷ 3 = 1 is less than 3 ÷ 1 = 3.