How do you determine the limiting reactant using gas volumes?

You determine the limiting reactant using gas volumes by comparing the ratio of the volumes of the reactants to their stoichiometric ratio.

In a chemical reaction involving gases, the limiting reactant can be determined by comparing the ratio of the volumes of the reactants to the ratio of the coefficients in the balanced chemical equation (also known as the stoichiometric ratio). This method is based on Avogadro's law, which states that equal volumes of gases, at the same temperature and pressure, contain an equal number of molecules.

To determine the limiting reactant, you first need to balance the chemical equation for the reaction. This will give you the stoichiometric ratio of the reactants. For example, in the reaction between hydrogen and oxygen to form water, the balanced equation is 2H2(g) + O2(g) → 2H2O(g). The stoichiometric ratio of hydrogen to oxygen is 2:1.

Next, compare the ratio of the volumes of the reactants to the stoichiometric ratio. If the ratio of the volumes of the reactants is the same as the stoichiometric ratio, then the reactants are in the correct proportions and will completely react with each other. If the ratio of the volumes of the reactants is not the same as the stoichiometric ratio, then one of the reactants is in excess and the other is the limiting reactant.

The limiting reactant is the one that is completely consumed in the reaction. It determines the maximum amount of product that can be formed. Once the limiting reactant is used up, the reaction stops, even if there is still some of the other reactant left. Therefore, by comparing the volumes of the reactants to their stoichiometric ratio, you can determine which reactant will be used up first and thus identify the limiting reactant.