Of, relating to, used in, or marked by stoichiometry
Stoichiometric. The exact percentage of two or more substances which will react completely with each other leaving no unreacted residue. For example, a 7% mixture of methane by volume in air will react completely with the oxygen present leaving only CO2 and H2O as residue. If the methane concentration here is less than 7%, there would be oxygen left over. If the methane concentration were greater than 7%, there would be methane left over.