AVOGADRO'S LAW

The behavior of gases described by Boyle’s, Charles’s, and Dalton’s laws is nearly the same for all gases. Avogadro’s law states that under identical conditions of temperature and pressure, equal volumes of different gases contain equal numbers of particles (atoms or molecules).
The temperature 0ºC (32ºF) and the pressure equal to the pressure Earth’s atmosphere exerts at sea level are called standard temperature and pressure (STP). According to Avogadro’s law, 1 cubic meter of oxygen at STP contains the same number of particles as 1 cubic meter of nitrogen at STP. Restated, Avogadro's law says that one mole of any gas at STP occupies a volume of 22.4 liters. A mole is 6.02 × 10²³ basic particles (atoms or molecules) of a substance. The extremely large number 6.02 × 10²³ is called Avogadro's number.