Limiting Reagent the limiting reagent is the compound which is less than the stoichiometric amount required (the chemical which prevents the reaction from going on any further). It is crucial when attempting to determine the limiting reagent that your reaction equation is balanced!

How to determine the limiting reagent:

1. Write the balanced equation for the reaction

2. calculate the actual moles used experimentally for that reaction

3. the limiting reagent is the compound which is less than the stoichiometric amount required.

For example:
The stoichiometry for the mixing of H2 and O2 to form water = 2 equivalent of hydrogen react with 1 equivalent of oxygen to yield 2 equivalents of waters (as represented in the below balanced equation).

(stoichiometry)

However, if only 1.9 moles of hydrogen and 1.0 moles of oxygen were used then hydrogen would be considered the limiting reagent.

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