CHE 1: Chemical Composition - Mass Composition and Moles

Vocabulary flashcards covering chemical composition, combustion analysis, percent composition, moles, Avogadro's number, molar mass, and empirical formulas from General Chemistry Lecture 6.

Combustion Analysis

A chemical method used to measure the amount of each element in a sample by reacting it with oxygen to produce compounds such as $CO_2$ and $H_2O$, allowing the calculation of the original sample's elemental mass composition.

Percent Composition by Mass

The percentage of a compound's total mass contributed by each constituent element, calculated as: $\text{\% Element} = \frac{\text{mass of Element}}{\text{mass of sample}} \times 100\%$.

Mole ($n$)

The SI base unit for amount of substance, defined as the amount containing the same number of elementary entities (atoms, molecules, or ions) as the number of atoms in exactly $12\,g$ of $^{12}C$.

Avogadro's Number ($N_A$)

The constant denoting the number of elementary entities per mole of a substance, equal to $6.022 \times 10^{23}\,\text{entities/mol}$.

Formula Unit

The lowest whole-number chemical ratio of ions, an individual atom, or a molecule that serves as the representative entity of a substance (such as a $Cu$ atom for copper, an $O_2$ molecule for oxygen gas, or a $Na_2SO_4$ unit for sodium sulfate).

Molar Mass

The mass in grams of $1\,\text{mol}$ of any chemical substance, expressed in the units of $g/mol$.

Atomic Mass to Molar Mass Equivalence

The numerical equality where the average atomic mass of an individual atom in atomic mass units ($amu$) is equivalent to the molar mass of that element in grams per mole ($g/mol$).

Molar Mass of a Compound

The mass in grams of one mole of a compound, calculated as the sum of the molar masses of its component elements multiplied by their respective stoichiometric subscripts from the chemical formula.

Empirical Formula

A chemical formula showing the simplest whole-number molar and atomic ratio of the elements present in a compound rather than the total number of atoms in a molecule.

Mole-to-Particle Conversion Factor

A conversion factor based on Avogadro's number, formatted as $\frac{6.022 \times 10^{23}\,\text{formula units}}{1\,\text{mol}}$, used to convert between moles of a substance and its number of individual particles.

Mass-to-Mole Conversion Factor

A conversion factor based on molar mass, formatted as $\frac{1\,\text{mol}}{\text{molar mass in } g}$, used to convert a substance's measured mass in grams into its corresponding number of moles.