1.2 Amount of Substance

Vocabulary practice flashcards covering stoichiometric definitions, gas calculations, solutions, titration techniques, and experimental uncertainties based on the lecture notes.

The mole

The amount of substance in grams that has the same number of particles as there are atoms in $12\text{ grams}$ of carbon-12.

Avogadro's constant ($L$)

The number of specified entities in one mole of any substance, defined as $6.022 \times 10^{23}\text{ entities}$.

Relative atomic mass ($A_r$)

The average mass of one atom compared to one twelfth of the mass of one atom of carbon-12.

Relative molecular mass ($M_r$)

The average mass of a molecule compared to one twelfth of the mass of one atom of carbon-12.

Empirical formula

The simplest whole number ratio of atoms of each element present in a compound.

Molecular formula

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

Water of crystallisation

Water molecules chemically bonded into the crystalline structure of a hydrated compound, which can be removed as water vapour upon heating.

Hydrated salt

A crystalline salt that contains water of crystallisation within its crystal lattice.

Molar concentration

The amount of solute in moles dissolved per unit volume of solution in $dm^3$, expressed in $mol\,dm^{-3}$ or $M$.

Mass concentration

The concentration of a solution measured in terms of the mass of solute per volume of solution, with the unit $g\,dm^{-3}$.

Ideal Gas Equation

The equation of state given by $PV = nRT$, where $P$ is pressure in $Pa$, $V$ is volume in $m^3$, $n$ is moles of gas, $R = 8.31\,J\,K^{-1}\,mol^{-1}$, and $T$ is temperature in $K$.

Reacting gas volumes principle

The principle stating that equal volumes of any gases measured under the same conditions of temperature and pressure contain equal numbers of molecules (or atoms for monatomic gases).

Percentage yield

A calculation evaluating reaction conversion efficiency, defined as $\frac{\text{actual yield}}{\text{theoretical yield}} \times 100$.

Percentage atom economy

A measure of synthetic efficiency indicating how much of the reactant mass is converted into the desired product, calculated as $\frac{\text{mass of useful products}}{\text{mass of all reactants}} \times 100$.

Concordant titre results

Titre readings that are within $0.10\,cm^3$ of each other, indicating high accuracy and repeatability in a titration.

Percentage apparatus uncertainty

The percentage error associated with experimental equipment, calculated as $\frac{\text{uncertainty}}{\text{measurement made on apparatus}} \times 100$.