Define Mole in Chemistry

Updated on Jan. 8, 2021 03:19 PM IST by Lakshmi Arya


  1. The word "mole" was introduced around 1896 by Wilhelm Ostwald from Latin word moles meaning a 'heap' or ' pile' ( of atoms or molecules).
  2. The unit mole was accepted in 1967.
  3. One Mole of any species (atoms, molecules,ions or particles) is that quantity in number having a mass equal to It's atomic or molecular mass in grams.
  4. A group of 6.022×1023 particles (atoms, molecules or ions ) of a substance is called a mole of that substance. 1 mole of atoms= 6.022×1023 atoms. 1 mole of molecules= 6.022×1023 molecules.

Example- In one Mole of oxygen gas(O2) there are 6.022×1023 molecules present in it and it's molecular mass is 16×2=32u.
The mass of 1 mole of a substance is equal to it's relative Atomic or molecular mass in gram.
1 mole=6.022×1023 in number  =relative mass in grams.
1mole hydrogen (H) = 6.022×1023atoms = 1g of hydrogen atom = atomic mass of H atom 1u.

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