1.4 The mole

• SI unit of amount of substance

• One mole = Avogadro constant number of entities

• Convert between amount of substance and number of specified particles

• Compared to ¹²C standard

• Determine relative formula mass from relative atomic masses

• Units: g mol⁻¹

• Relationships: particles ↔ moles ↔ mass

• Solve mass, mole, and particle problems using n = m/M

• Empirical: simplest ratio of atoms

• Molecular: actual number of atoms in molecule

• Interconvert percentage composition and empirical formula

• Determine molecular formula from empirical formula and molar mass

• Determined by amount of solute and volume of solution

• Solve concentration, amount, and volume problems; square brackets mean molar concentration

• Equal volumes of gases (same T, P) contain equal numbers of molecules

• Mole ratio calculations with gas volumes

• Use gas volume ratios from balanced equations