Question

what is the mole of HCl

Answer 1

Definition of mole

To start with, you must be very clear about what exactly does a mole represent.

The mole is the unit of measurement in the International System of Units (SI) for amount of substance. 1 Mole is just a number whose value is equal to the Avagadro’s number i.e. 6.022 * 1023. So, when someone claims of a matter to be of 1 mole in quantity, that implies that the matter under consideration contains exactly 6.022 * 1023 number of particles (atoms, molecules, ions, electrons or any other elementary entities). This is very similar to the unit ‘dozen’, which is a common analogy used to explain the concept of mole, a dozen is always equal to 12 irrespective of the object referred to.

When dealing with particles of the size of atoms and molecules, it becomes very difficult to do the calculations as they are present in very large numbers. Even in a small sample of an element or chemical compound, generally the number of elementary particles are in the higher order of 10. So to make these calculations simpler, mole was defined. While solving problems, the numbers are expressed in terms of Avogadro number, making the solution to the problems in physical chemistry simpler.