Concept of Mole

  1. A mole is defined as the amount of substance which contains the Avogadro Number of particles.
  2. The Avogadro Number (or Avogadro Constant) is defined as the number of atoms in 12 g of the carbon-12 isotope, which is equal to 6.02 x 1023.
1 mole = 6.02 x 1023

Example:
1 mol of atoms = 6.02 x 1023 atoms
½ mol of atoms = 3.01 x 1023 atoms
¼ mol of atoms = 1.505 x 1023 atoms.

Note:
The particles in a material can be atoms, molecules or ions.
Therefore
1 mol potassium atom = 6.02 x 1023 potassium atom
1 mol carbon dioxide molecules = 6.02 x 1023 of carbon dioxide molecules.
1 mol sulphate ions = 6.02 x 1023 sulphate ions.

Example:
Find the number of atoms in:
  1. 2 mol ferum 
  2. 3.6 mol zink 
  3. 2.8 mol zink 
  4. ¼ mol ferum 
Answer:
  1. 2 mol iron = 2 x 6.02 x 1023 = 1.204 x 1024  iron atoms
  2. 3.6 mol zink =   3.6 x 6.02 x 1023 = 2.167 x 1024  zink atoms
  3. 2.8 mol zink = 2.8 x 6.02 x 1023 = 1.686 x 1024 zink atoms
  4. ¼ mol iron = ¼ x 6.02 x 1023 = 1.505 x 1023  iron atoms.

Mole and mol

  1. Mole is the unit of amount of substance.
  2. “mol” is the symbol of mole.