Mole and Avogadro's Number - Home of Knowledge

Mole and Avogadro’s Number

Mole (Chemist secret unit)

A mole is defined as the amount(mass) of a substance that contains 6.02 x 1023 number of particles (atoms, molecules or formula units). OR mole is the atomic mass, molecular mass or formula mass of a substance expressed in grams is called mole. It establishes a link between mass of a substance and number of particles. It is abbreviated as ‘mol’.


Avogadro’s Number: Avogadro’s number is the number of particles ( atoms, ions or molecules) in one mole of a substance. OR 6.022 χ 1023 number of atoms, molecules or formula units is called avogadro’s number.  It is symbolized by NA and has a value of

6.022 χ 1023.

  • one mole of carbon =12 gram= 6.02 x 1023 atoms of carbon = 1NA.
  • one mole of water= 18gram= 6.02 x 1023 molecules of H2O= 1NA.
  • one mole of sodium chloride= 58.5gram= 6.02 x 1023 formula units of NaCl = 1NA.


Amaedo Avogadro

(1776-1856) was an Italian scholar. He is famous for molecular theory commonly known as Avogadro’s law. In tribute to him, the number of particles (atoms, molecules, ions) in mole of a substance 6.02 x 1023is known as the Avogadro’s constant.

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