Stoichiometry is the branch of chemistry that deals with the quantitative relationships and calculations between substances involved in a chemical reaction.
A chemical formula is a combination of chemical symbols and numbers that represents the composition of a substance. It tells us the types and number of atoms present in a molecule or compound.
A chemical formula is written with the chemical symbols of the elements present in a substance, with subscripts indicating the number of atoms of each element. For example, the chemical formula for water is H2O, which means two hydrogen atoms and one oxygen atom.
Empirical formulas show the simplest ratio of elements in a compound, while molecular formulas show the actual number of each element present in a molecule. For example, the empirical formula for glucose is CH2O, while the molecular formula is C6H12O6.
Stoichiometry is used to calculate the amount of reactants needed to produce a certain amount of product, or the amount of product that can be produced from a given amount of reactants. It also allows us to determine the limiting reactant and the theoretical yield of a reaction.