After Avogadro’s law finally was accepted, some scientists tried to calculate how many molecules might be present in a specific weight of a substance.
Eventually, they calculated that 22 liters of gas contains 602 billion trillion molecules.
This is usually written as 6.02 x 10^23 (to the twenty-third power) and is referred to as Avogadro’s number, even though Avogadro had nothing to do with it.
It is also referred to as one mole of the substance.
To give an idea of its size, if you were able to count atoms at a rate of 10 million a second, it would take you about 2 billion years to count the atoms in one mole.
Avogadro’s law is a gas law named after Amedeo Avogadro who hypothesized the theory in 1811.