What is mole concept and how to find the mole of an element

Avogadro’s number helps in many numerical calculations. Here, we will discuss the important relationships in the mole concept.

Avogadro’s number may be defined as the number of atoms present in one gram atom of the element. It is also equal to the number of molecules present in one gram molecule of the substance.

1 mole of H atoms = 6.022 * 10^23 atoms of Hydrogen

Therefore, a mole is a unit of counting particles like atoms, molecules, ions, electrons, protons etc. which is equal to 6.022 * 10^23

What is Gram atomic mass / Gram molecular mass in mole concept

Amount of the atom / molecule expressed in grams is called gram atomic mass / gram molecular mass.

1 mole of Carbon atoms = 12 g ( Atomic mass of C = 12 a.m.u. )

One mole of Oxygen atoms = 16 g ( Atomic mass of O = 16 a.m.u. )

1 mole of Oxygen molecule = 32 g ( molecular mass of O2 = 32 a.m.u. )

One mole of H2O molecule = 18 g ( molecular mass of H2O = 18 a.m.u. )

Mole concept @basicsofchemistry.com

What is Avogadro number

A mole contains Avogadro’s number of atoms / molecules.

1 mole of Carbon atoms = 6.022 * 10^23 atoms of Carbon

One mole of Oxygen atoms = 6.022 * 10^23 atoms of Oxygen

1 mole of Oxygen molecules = 6.022 * 10^23 molecules of Oxygen

Mole concept in terms of volume

Amount of the gas weighs equal to a volume of 22.4 L at S.T.P.

1 mole of CO2 gas = 22.4 L of CO2 gas at S.T.P.

One mole of O2 gas = 22.4 L of O2 gas at S.T.P.

Mole concept for Ionic compounds

A mole of an ionic compound is equal to the amount of the substance called as gram formula mass.

1 mole = gram formula mass of the compound = 6. 022 * 10^23 formula units of the compound.


  1. What is the mass of one mole ?

Answer : The mass of one mole of a substance is equal to the atomic weight / molecular weight

2. How many atoms are present in a mole ?

Answer : 1 mole contains 6. 022 * 10^23 atoms.

3. What is mole of O2 ?

Answer : 1 mole of O2 gas is 32 g

Check out the structure of NH3 here

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