Question

How many particles are in a mole?

Answer 1

Hint: The answer here is dependent on the calculation of total number of molecules present which takes into account the Avogadro number of molecules and the value of Avogadro constant value.

Complete step by step answer:
- In the classes of general chemistry, we have come across the very basic concept which deals with the calculation of number of molecules present in the compound and also about the Avogadro constant.
- Let us see what one molecule of substance is or in general how many particles are in one mole and how it can be determined.
- According to the Avogadro law, mole concept that is one mole of a substance is defined as ‘the amount of a substance which contains as many elementary particles as that the number of carbon atoms present in 12 g of C – 12 isotope’.
- Avogadro proposed a law which states that ‘equal volumes of different gases measured under the same conditions of temperature and pressure contain the same number of molecules’.
This was initially not well known but 50 years later his works were known and later the Avogadro constant value was derived based on his law.
- This value was found by the experiment which gave the Avogadro number and was derived as shown below,
One atom of C-12 weighs about $1.992648\times {{10}^{-23}}g$
One mole of C-12 weighs 12g.
Therefore, 12 g of C-12 contains $\dfrac{12}{1.992648\times {{10}^{-23}}}=6.0221367\times {{10}^{23}}\approx 6.022\times {{10}^{23}}$ atoms.
Thus, there are $6.022\times {{10}^{23}}$ atoms in exactly one mole of atom.
Therefore, the correct answer is there are numbers $6.022\times {{10}^{23}}$ of particles in one mole of a substance.

Note: Note that the unit of this Avogadro number is defined as the number of particles present per mole of a substance and therefore the unit is written as $mo{{l}^{-1}}$ and thus this Avogadro number can be written as $6.022\times {{10}^{23}}mo{{l}^{-1}}$