What are exactly N,No,n,m,M and how to solve mole concept practicals based on this. Explain in detail.
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The mole concept is one of the topics with which you kick-off your preparation of physical chemistry in class 11. One of the reasons for it being taught earlier is that the concept of mole will be required in almost every other topic of physical chemistry that you study later, irrespective of the complexity of that topic. Apart from its relevance in chemistry, it must be noted that mole concept is one of the easier topics of chemistry, so, make sure you do study it well and go through each and every point in this topic. To help you in your preparations, here, I have discussed the relevant points and formulae that you must know, related to the concept of mole.
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.
Why was the concept of mole needed?
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.
Reference used for defining the Avogadro number:
Since a mole is used to define quantity of matter, it is necessary that we have a reference with respect to which it is being defined. A mole or Avogadro number is defined as the amount of substance that contains as many elementary entities as there are in exactly 12 gm of Carbon-12. The number of atoms in 12 gm of Carbon-12 is called Avogadro’s number (NA).
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.
Why was the concept of mole needed?
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.
Reference used for defining the Avogadro number:
Since a mole is used to define quantity of matter, it is necessary that we have a reference with respect to which it is being defined. A mole or Avogadro number is defined as the amount of substance that contains as many elementary entities as there are in exactly 12 gm of Carbon-12. The number of atoms in 12 gm of Carbon-12 is called Avogadro’s number (NA).
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