In Physico-chemical,the Loschmidt constant or Loschmidt's number (symbol: n0) is the number of particles (atoms or molecules) of an ideal gas in a given volume (the number density). It is usually quoted at standard temperature and pressure.
Loschmidt constant (273.15 K, 100 kPa) 2.651 6462 e25 0.000 0024 e25 m^-3