Stoichiometry: Calculations with Chemical Formulas and Equations

Chemical Properties

The characteristics describing the reactions a substance undergoes to form new substances.

Law of Conservation of Mass

The principle formulated by Antoine Lavoisier in 1789 stating that matter is neither created nor destroyed in chemical operations, meaning an equal amount of matter exists both before and after an experiment.

Reactants

The starting substances consumed in a chemical reaction, written on the left side of a chemical equation.

Products

The new substances produced in a chemical reaction, written on the right side of a chemical equation.

Stoichiometric Coefficients

The numbers placed in front of chemical formulas in a chemical equation that give the ratio of reactants and products involved in the reaction.

Combination Reaction

A chemical reaction in which two or more reactants combine to form a single product, represented generally as $A + B \rightarrow C$.

Decomposition Reaction

A chemical reaction in which a single reactant breaks apart to form two or more substances, represented generally as $C \rightarrow A + B$.

Formula Weight (FW)

The sum of the atomic weights of the atoms in the chemical formula of a substance, expressed in atomic mass units ($\text{amu}$).

Molecular Weight (MW)

The weight of a single molecule, calculated as the sum of atomic weights when the chemical formula of a substance represents its molecular formula.

Percent Composition

The percentage by mass contributed by each element in a compound