Avogadro’s number

Avogadro law:

Amadeo Avogadro is an Italian scientist known for his hypothesis that at constant temperature and pressure, Gases having equal volumes contain equal number of molecules. This law is related to the ideal gas equation and well-founded for real gases at high concentrations of temperature and low pressure. At that time, other scientists rejected the theory, but after his death, the theory gained acceptance and all his value and honour. And now we study this theory as Avogadro’s law. He also used his hypothesis to explain Joseph-Louis gay lussac’s law. The respiration process is one of the examples of Avogadro’s law; during inhaling, molar quantity of air increases in the lungs. V is directly proportional to n, in which V is gas volume, and n denotes the number or amount of gaseous substances. We can write it as a formula – 

                V/n = K 

Here, K is the constant. The formula indicates that if we increase the number of gaseous substances, the volume of gas also increases. The gas occupies volume is calculated by –

                 V1 / n1 = V2/n2

Avogadro’s law has a limitation that it is applicable only for real gases. 

Avogadro’s number-

Several particles are present in one mole of any substance called Avogadro’s number. Avogadro’s number is denoted by NA and has 6.023 X 1023  particles; it is not the exact value . Thus the precise value of Avogadro’s number is 6.02214154 X 1023 .  Avogadro’s number is also called Avogadro’s constant. The main section of Avogadro’s number relates between molar mass on an atomic scale to physical mass on a Human scale. Avogadro’s number is similar to the concept of dozen and gross, as a dozen contains 12 molecules while in gross, there are 144 molecules, and in Avogadro’s number, there are 6.023 X 1023 molecules. Avogadro’s number can be compared with a large number by scientists nowadays. According to Avogadro, the number one mole mass of a substance equals the molecular weight; this property helps in the chemical calculation.

History of Avogadro’s number-

 Amadeo Avogadro is famous for his hypothesis, but he didn’t discover Avogadro’s number. The first who identified the number of particles is Josef loschmidt; he used kinetic theory for assuming several particles. Jean Baptiste Perrin (French physicist) was the first who used the term Avogadro’s number Perrin’s Brownian motion work (microscopic particles placed in liquid or a gas experienced random movement) describe an estimate of Avogadro’s number. Avogadro’s number needs a single quantity measurement of atomic or microscopic scales, which was first done by Robert Milikan (he discovered a charge on electrons). According to Faraday, the mole charge of electrons is divided by the charge of an electron to get the value of Avogadro’s number, i.e. 6.02214154 X 1023 simply 6.023 X 1023 .

Mole

Mole is the SI unit ( atoms, molecules, ions, etc.) which is used to determine the substance amount. It can be written as – mol. And it contains 6.02214076 X 1023 molecules. Mole can be written in the unit as mol. 

Importance of Avogadro’s constant

By dividing the mole charge of electrons to the charge of an electron to get the value 6.02214154 X 1023, known as Avogadro’s number and is also called Avogadro’s constant. There is much importance which is shown by Avogadro’s constant and some importance are – 

• Forms the bridge between large numbers and possible numbers means that It shows a relation between large numbers and different units.
• Avogadro’s number can write one mole mass of a substance in smaller numbers.
• We can get ratios between reactants and products in chemical equations by Avogadro’s number.

• The gas constant ( R ) and the Boltzmann constant kB shows a relationship. 

               R = kB NA 

• Also has a relationship between Faraday constant and elementary charge. 

               F = NA e

Conclusion

Avogadro’s number is named after the death of Amadeo Avogadro in his honour. Avogadro doesn’t discover the Avogadro number; he only gives the hypothesis that at constant temperature and pressure, the volume of all gases has the same number of molecules. His hypothesis is for only real gases. The respiration process is the best example of Avogadro’s law, which shows that molar quantity increases in the lungs during inhaling. French physicist Jean Baptiste Perrin first used Avogadro’s number. Mole charge of electrons is divided by the charge of an electron to get the value of Avogadro’s number, i.e. 6.02214154 X 1023 particles per mole, where a mole is a SI unit that is used to determine the amount of substance. Avogadro’s number can state the exact number of atoms of elements (such as carbon or silicon), as Avogadro’s number is the fundamental constant of chemistry. Avogadro’s constant bridges large numbers and possible numbers or different units. The ratio of products and reactants can be identified with the help of Avogadro’s number. It is the fundamental constant of chemistry as it compares molecules or different units.