1.2 The mole concept

Define mole

The amount of substance that contains as many particles as there are atoms in exactly 12 g of carbon-12

Define Avogadro’s constant (L)

The number of particles in one mole of substance, equal to 6.02 × 10²³ mol⁻¹

Define molar mass (M)

The mass of one mole of a substance, measured in g mol⁻¹

Define empirical formula

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

Define molecular formula

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

Define hydrated compound

A compound that contains water molecules chemically bound within its structure

Define anhydrous compound

A compound that contains no water of crystallisation

Define relative atomic mass (Ar)

The weighted mean mass of the atoms of an element relative to 1/12 of the mass of a carbon-12 atom

Define relative molecular mass (Mr)

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

Define relative formula mass

The sum of the relative atomic masses of all atoms in the formula unit of an ionic compound

Define molar volume (at STP)

The volume occupied by one mole of gas at standard temperature and pressure, equal to 22.7 dm³ mol⁻¹

Define STP

Standard conditions of 273 K and 100 kPa

Define limiting reactant

The reactant that is completely consumed first, determining the amount of product formed

Define excess reactant

Any reactant that remains after the limiting reactant has been completely used

Define theoretical yield

The maximum amount of product that can be formed from the limiting reactant, assuming complete reaction

Define actual yield

The amount of product actually obtained from a reaction

Define percentage yield

The actual yield expressed as a percentage of the theoretical yield

Define percentage atom economy

A measure of the efficiency of a reaction, calculated by comparing the molar mass of the desired product to the total molar mass of all products