Question

What are limiting and excess reactants?

Answer 1

The excess reagent is that reagent in a chemical reaction which has a greater amount than the necessary amount to react completely with the limiting reactant. It is the reagent that remain after a chemical reaction has reached equilibrium.

Limiting reagent is that reagent in a reaction that will limit how much product can be formed. It is the reagent that can not remain after a chemical reaction has reached equilibrium.

$N_2+3H_2\to 2N{H}_3$

For example if we have 6 moles of $N_2$ and 5 moles of $H_2$. This means that you will only be able to make 3.5 moles of $N{H}_3$ rather than 4 moles because we don’t have enough $H_2$. In this case, $N_2$ is the excess reagent and $H_2$ is the limiting reagent.