Chapter 3 Vocabulary - Chemical Stoichiometry

Vocabulary terms and definitions from Chapter 3 covering basic mole concepts, chemical formulas, and stoichiometry.

Mole

A quantity equal to Avogadro’s number of things.

Avogadro’s Number

$6.02214076 \times 10^{23}$; the number of particles in one mole.

Molar Mass

The mass in grams of one mole of a substance; expressed in $g\,mol^{-1}$.

Mass Percent (Percent Composition by Mass)

The percentage contribution by mass of each element in a compound.

Empirical Formula

The simplest whole-number ratio of atoms in a compound.

Molecular Formula

The actual number of atoms of each element in a molecule.

Chemical Equation

A symbolic representation of a chemical reaction showing reactants and products.

Reactants

Substances consumed during a chemical reaction.

Products

Substances formed during a chemical reaction.

Coefficient

A number placed before a chemical formula in an equation indicating relative amounts of substances.

Stoichiometry

The analysis of mole relationships among reactants and products in a chemical reaction.

Limiting Reactant (Limiting Reagent)

The reactant that is completely consumed first and limits the amount of product formed.

Excess Reagent

A reactant that remains after the limiting reactant has been completely consumed.

Theoretical Yield

The maximum amount of product predicted by stoichiometric calculations.

Actual Yield

The amount of product actually obtained experimentally.

Percent Yield

The ratio of actual yield to theoretical yield multiplied by $100\%$.

Balanced Chemical Equation

A chemical equation in which equal numbers of each type of atom appear on both sides of the equation.

Formula Weight

The sum of the atomic masses of all atoms in a chemical formula.

Empirical Formula Method

A stepwise procedure used to determine the empirical formula from percent composition data.

Molecular Mass

The sum of the atomic masses of all atoms in a molecule.

Percent Composition

The relative mass contribution of each element in a compound expressed as a percentage.

Hydrate

An ionic compound containing a specific number of water molecules within its crystal structure.

Anhydrous Compound

A compound from which water molecules have been removed.

State Subscripts

Symbols such as $(s)$, $(l)$, $(g)$, and $(aq)$ indicating the physical state of substances in a chemical equation.

Stoichiometric Amounts

Reactant quantities mixed in exact mole ratios required by the balanced chemical equation.