Mole Concept

Mole concept states that it is easier to use the quantity of substance in a number of molecules or atoms instead of their mass so the unit called Mole is used.

If the element is weighed and it is equal to its atomic weight in grams, then it contains a certain amount of element, which represents one mole of an element, and that certain amount of element is 6.022 x 10²³ atoms of an element. 1 mole of any molecule or atom is equal to its atomic mass or molecular mass in grams. The number of particles in 1 mole = 6.022 x 10²³ atoms or molecules and this is known as the Avogadro number.

The number of particles in 1 mole: 

• 1 mole of hydrogen atoms shows 6.022 × 10²³ hydrogen atoms.
• 1 mole of hydrogen molecules shows 6.022 × 10²³ hydrogen molecules.
• 1 mole of water molecules shows 6.022 × 10²³ water molecules.

Mathematically, the number of moles is defined as:

Example 1: Find the number of moles present inside the 24.088 ×10²³ particles of water.

Answer:

Given that, 

The number of particles present, N = 24.088 ×10²³

The number of moles (n) = Number of particles (N) / Avogadro number (N₀)

                                         = 24.088 ×10²³ / 6.022 x 10²³

                                         = 4 moles

Molecular Mass is the mass of all the atoms present in a molecule. In ancient India and Greece, philosophers have first given the idea of atoms and deeply studied them. Around 500 BC.

Everything around is made up of very small units these units are atoms in the language of science, very small in the sense is in the range of 0.1 – 0.5 nanometers. These atoms join to form molecular which then join to form matter. For example, two atoms of hydrogen and one atom of oxygen joins to form one molecule of H₂O which is water. Hence, the molecular mass in this case of H₂O will be given as sum of mass of two atoms of hydrogen and one atom of oxygen.