Question

Why is a balanced chemical equation needed for stoichiometric calculations?

Answer 1

Because by definition stoichiometry means `"in the right measure"`. If you don't have a balanced chemical equation your proportions will be out!

Explanation:

Mass is conserved for every chemical process and equation, whereas it may not be conserved for every nuclear reaction. Every reactant particle must thus correspond to a product particle; and if you start with `10*g` with respect to reactants, there must be `10*g` with respect to products. If not, someone (you) has made a mistake.