Explanation

Stoichiometry calculations can only be carried out when all of the above are true:

Irreversible reactions:

Stoichiometry calculations are based on the assumption that the reaction proceeds to completion, meaning all reactants are used up to form products. 

No side reactions:

Side reactions would introduce additional products and complicate the calculations. 

At least one reactant consumed completely:

Stoichiometry calculations determine the amount of products formed based on the amount of a limiting reactant.