Define mole concept?

The Mole Concept:

One mole of a substance (atoms, molecules, ions, or particles) is that quantity in number having a mass equal to its atomic or molecular mass in grams. One mole of any substance contains 6.022 * 10 23 particles (atoms, molecules, or ions). This means that one mole atom of any substance contains 6.022 *1023 atoms. Similarly, one mole molecule of any substance contains 6.022 *1023 molecules, and one mole ion of any substance contains 6.022 *1023 ions. Hence, the mass of a particular substance is fixed.

The number 6.022 * 1023 is an experimentally obtained value and is known asAvogadro’s number or Avogadro constant (represented by N o ). It is named after the Italian scientist, Amedeo Avogadro.

  • 136

The Mole Concept:

One mole of a substance (atoms, molecules, ions, or particles) is that quantity in number having a mass equal to its atomic or molecular mass in grams. One mole of any substance contains 6.022 � 10 23 particles (atoms, molecules, or ions). This means that one mole atom of any substance contains 6.022 �10 23 atoms. Similarly, one mole molecule of any substance contains 6.022 �10 23 molecules, and one mole ion of any substance contains 6.022 �10 23 ions. Hence, the mass of a particular substance is fixed.

The number 6.022 � 10 23 is an experimentally obtained value and is known as Avogadro’s number or Avogadro constant (represented by N o ). It is named after the Italian scientist, Amedeo Avogadro.

Thus, 1 mole of oxygen atoms (O) = 6.022 �10 23 oxygen atoms.

1 mole of oxygen molecules (O 2 ) = 6.022 � 10 23 oxygen molecules.

1 mole atoms of an element has a mass equal to the gram atomic mass of that element. Hence, the mass of 1 mole molecules is equal to its molecular mass in grams. The atomic mass of an element is the mass of its atom in atomic mass units (u). By taking the same numerical value of atomic mass and changing the units from ‘u’ to ‘g’, the mass of 1 mole atoms of that element is obtained. The mass of one mole of atoms is known as the molar mass of atoms, gram atomic mass, or gram atoms. For example, the atomic mass of nitrogen is 14 u, and the gram atomic mass of nitrogen is 14 g.

Similarly, the molecular mass of a substance gives the mass of a molecule of that substance in atomic mass units (u). Therefore, as discussed earlier, by taking the same numerical value of molecular mass and by changing its units from ‘u’ to ‘g’, the mass of one mole molecules of that substance can be obtained.

Therefore, the mass of one mole molecules of any substance is equal to the gram molecular mass of that substance.

For example, 12 u of carbon contains only 1 atom of carbon, and 12 g carbon contains 1 mole atoms of carbon i.e. 6.022 � 10 23 number of carbon atoms. Similarly, the molecular mass of oxygen (O 2 ) is 32 u. Thus, its gram molecular mass is 32 g. Thus, 32 g of O 2 contains 1 mole molecules of O 2 , i.e., 6.022 � 10 23 number of molecules of oxygen.

  • 30
What are you looking for?