Stoichiometry is the branch of chemistry that deals with the quantitative relationships between reactants and products in a chemical reaction.
Stoichiometry is important because it allows us to predict the amount of product that will be formed in a chemical reaction, and to determine the amount of reactant needed to produce a desired amount of product.
Stoichiometric ratios can be calculated by using the coefficients in a balanced chemical equation. The coefficient of each reactant or product represents the number of moles involved in the reaction.
The limiting reactant is the reactant that is completely consumed in a chemical reaction, while the excess reactant is the reactant that is left over after the limiting reactant is completely used up.
For example, if 2 moles of hydrogen react with 1 mole of oxygen to produce water according to the equation 2H2 + O2 → 2H2O, how many moles of water will be produced? Using the stoichiometric ratio of 2:1 for hydrogen to oxygen, we can determine that 2 moles of hydrogen will produce 2 moles of water. Therefore, 1 mole of oxygen will produce 1 mole of water. So, the total moles of water produced will be 2 + 1 = 3 moles.