Answer:
The limiting reactant can be described as the substance that is depleted first and stops
Explanation:
Imagine you have hydrogen and oxygen to produce water.
The reaction is: 2H₂(g) + O₂(g) → 2H₂O(g)
You have 1 mol of each reactant. As you see ratio is 2:1, so the limiting reactant is the hydrogen.
You know by stoichiometry, that 2 moles of H₂ need 1 mol of O₂ to react
If I have 1 mol of H₂, I will need the half of moles of O₂, so 0.5 moles. It is ok because I have 1 mole, as I need the half, then half a mole will remain unreacted. This is what is called excess reagent,
If I make to react 1 mol of oxgen I need 2 moles of H₂. As I have 1 mol, of course I will need 2 moles but the thing is I have 1 mol.
This is the limiting reactant. I do not have enough of reactant so the reaction will happen until I complete to use it, that's why we can say that is depleted first and stops.
In a chemical reaction, when you have data of both reactants you can determine the limiting. Otherwise the excersise must tell that one ractant is in excess, to work with the limiting. Limiting reactant is the first step to work with the reaction, all the operations must be done by it. You do not use the reagent in excess
