Loschmidt number

(physics) The number of molecules in 1 cubic centimeter of an ideal gas at 1 atmosphere pressure and 0°C, equal to approximately 2.687 × 10¹⁹. Symbolized n₀.

fundamental constant The number of molecules per cubic metre in an ideal gas at s.t.p., = 2.686 8~ × 10²⁵, but see Loschmidt constant. (Originally defined within metric-c.g.s. as per cubic centimetre, = 2.686 8~ × 10¹⁹.) The value equals Avogrado's number divided by mole volume in relevant volumetric unit. It has itself been called Avogadro's number.