Molar Mass, Chemical Formulas, and Stoichiometry Vocabulary

Vocabulary flashcards covering mole concepts, formula determinations, balancing equations, and reaction stoichiometry from the combined lecture notes.

Mole

The chemist's standard unit for counting large numbers of very small entities, where $1cd\,mol$ contains exactly $6.022 \times 10^{23}$ particles.

Avogadro's Number

The defined constant $6.022 \times 10^{23}\,mol^{-1}$, representing the exact quantity of entities present in one mole of a substance.

Molar Mass

The mass in grams of one mole of a substance's entities (atoms, molecules, or formula units), expressed in units of $g\,mol^{-1}$.

Dimensional Analysis

A calculation track method using units of conversion factors to ensure numbers are correctly aligned to yield the intended target unit.

Mass Fraction

The fraction of a compound's total mass attributable to a specific constituent element, calculated as the mass of that element divided by the formula mass of the compound.

Mass Percent

The percentage composition by mass of an element in a compound, calculated by multiplying its mass fraction by $100$.

Empirical Formula

The simplest chemical formula for a compound showing the lowest whole-number ratio of moles of each constituent element.

Molecular Formula

A chemical formula giving the actual total number of atoms of each element in a single molecule, equal to a whole-number multiple of the empirical formula.

Empirical Mass

The calculated total mass corresponding to one empirical formula unit of a compound.

Isomers

Compounds sharing identical molecular formulas and molar masses but possessing different structural arrangements and distinct physical or chemical properties.

Elemental Analysis

An experimental technique used to determine the mass percent composition of elements within a compound to derive its empirical formula.

Combustion Analysis

An analytical method where an organic sample is completely combusted in oxygen to generate $\text{CO}_2(g)$ and $\text{H}_2\text{O}(g)$, allowing quantification of carbon, hydrogen, and other elements.

Stoichiometric Coefficient

A multiplier placed in front of a chemical formula in an equation to balance the number of atoms of each element on both sides.

Balanced Chemical Equation

A chemical equation in which the total count of each atom type is equal on both the reactant and product sides, satisfying the law of conservation of mass.

Stoichiometric Ratio

A mole-to-mole ratio derived directly from the coefficients of a balanced chemical equation used to relate relative quantities of reactants and products.

Limiting Reactant

The reactant that is completely consumed first in a reaction, limiting the maximum yield of product that can form.

Excess Reagent

A reactant present in a quantity greater than stoichiometrically required to react with the limiting reactant, leaving an unreacted portion after completion.

BCA Table

A structured reaction accounting table tracking molar quantities of reactants and products Before the reaction, during the Change, and After completion.

Theoretical Yield

The calculated maximum quantity or mass of product that can form assuming complete consumption of the limiting reactant.

Actual Yield

The actual measured mass of product isolated and recovered experimentally from a reaction.

Percent Yield

The ratio measuring reaction efficiency, defined by the formula $\frac{\text{actual yield}}{\text{theoretical yield}} \times 100$.