Moles notes

Species

Species

A molecule, atom, ion, or compound in an equation.

Mole

The amount of substance, measured in moles (mol).

Relative atomic mass

The weighted average mass of an element's isotopes relative to 1/12 the mass of a carbon-12 atom.

Relative formula mass (Mr)

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

Relative molecular mass (Mr)

A term for formula mass used with molecules.

Empirical formula

Represents the simplest whole number ratio of atoms of different elements in a compound.

Relative Atomic Mass (Ar)

The weighted average mass of an element's atoms compared to 1/12th of a carbon-12 atom.

Relative Formula Mass (Mr)

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

Mole (mol)

The SI unit for the amount of substance, containing 6.02 × 10²³ particles.

Amount of substance calculation

Amount of substance (mol) = mass (g) ÷ Mr.

Experimental formula determination

The formula indicates the simplest ratio of elements in a compound.

Water of crystallisation

Water molecules within the crystal structure of some salts.

Empirical formula

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

Molecular formula

Shows the actual number of atoms of each element in a molecule.

Percentage composition formula

Used to determine the percentage of each element in a compound.

Combustion

A method to determine the empirical formula by burning a metal in oxygen.

Reduction

A method to determine the formula of a compound by reducing it with hydrogen gas.

Accuracy in measurements

Ensuring precise mass measurements before and after reactions.

Completeness of reaction

Ensuring that the reaction has fully occurred for accurate results.

Safety considerations

Precautions when handling heated equipment and reactive gases.