Cambridge O Level Chemistry · Syllabus 5070 · Stoichiometry
Limiting reactant
What is Limiting reactant?
The limiting reactant is the reactant that is completely used up first in a chemical reaction and therefore sets the maximum amount of product that can form; it is identified by dividing each reactant's amount in moles by its coefficient in the balanced equation and taking the smaller result.
This definition is part of the Stoichiometry chapter in Cambridge O Level Chemistry.
Questions students ask about Limiting reactant
How do you find the limiting reactant?
Convert the amount of each reactant to moles, then divide each amount by its coefficient in the balanced equation. The reactant with the smaller quotient is the limiting reactant: it is completely used up first, so it alone decides the maximum amount of product that can form. Calculate the product from the limiting reactant, never from the one in excess, and finish by checking that the masses balance, including the mass of the excess reactant left over.