Stoichiometry Notes

Stoichiometry branch of chemistry that deals with the mass relationships of elements in compounds and the mass relationships between reactants and products in chemical reactions

Divided into two branches Composition Stoichiometry Reaction Stoichiometry

Composition Stoichiometry mass relationships of elements in compounds

Reaction Stoichiometry mass relationships among reactants and products in chemical reactions

All reaction-stoichiometry calculations require knowing the balanced chemical equation for the reaction under study. With the correct balanced equation and knowledge of the amount of one substance, it is possible to determine the amounts of all the other substances.

To solve any of these problems requires a mole-ratio - A conversion factor that relates the number of moles of any 2 substances involved in a chemical reaction.

Mole - Mole

Mole - Mass

Mass - Mole

Mass - Mass

Chemical equation help us understand and make predictions about chemical reactions without having to actually work the reactions in the laboratory, BUT, remember their limitations!

do not reveal conditions under which reactions actually occur can be written to describe reactions which do not occur do not tell the speed or pathway of reactions

These unrevealed factors may limit the actual amount of product obtained. Therefore, chemical equations are theoretical only.

The limiting reactant is The reactant that controls the amount of product formed in a chemical reaction. The substance not used up in a chemical reaction is sometimes called the excess reactant.

The theoretical yield is the maximum amount of product that can be produced from a given amount of reactant (calculated)

Actual yield is the measured amount of a product obtained from a chemical reaction

Percent Yield Is the ratio of the actual yield to the theoretical yield multiplied by 100.