Avogadro’s law. Molar volume

Avogadro’s law: at the same temperature and pressure, equal volumes of different gases contain the same number of molecules. In gases the distance between molecules is much larger than their size, so the volume depends mainly on the number of molecules. One mole of any substance contains 6.02·10²³ particles (the Avogadro constant); at standard conditions (0 °C and 101.3 kPa) 1 mol of any gas occupies 22.4 l, the molar volume Vₘ = 22.4 l/mol. Formulas: n = V : Vₘ, V = n·Vₘ. Gas density is ρ = M : Vₘ (g/l), and the density of one gas relative to another is D = M₁ : M₂. For example D(O₂/H₂) = 32 : 2 = 16; the average molar mass of air is 29 g/mol, so D(air) = M : 29. The law holds for gases; the volume of solids and liquids also depends on particle size.