We explain what Avogadro's number is, what is the value of this constant and a brief history of its invention.
What is Avogadro's number?
In chemistry, Avogadro's number or Avogadro's constant is called the number of particles constituents of a substance (normally atoms or molecules) that can be found in the amount of a mole of the substance. It is a factor of proportion that relates the mass molar (physical quantity that defines the mass of a substance per unit quantity of substance and is expressed in kg / mol) of a substance and the mass present in a sample.
The accepted value of this constant is 6.02214087 x 1023 mol-1.
At present, the term Avogadro's constant is used instead of “Avogadro's number”. The difference between the two terms is that Avogadro's constant contains units of measurement and Avogadro's number is dimensionless.
Jean Baptiste Perrin initially defined Avogadro's number as the number of atoms in a mole of hydrogen (H). This value was then redefined as the number of atoms in 12 grams of the carbon-12 isotope, and later, it was generalized to relate molar masses to amounts of substances.
An example that helps to understand this is: in 1 gram of hydrogen there are approximately 6.022 x 1023 hydrogen atoms, while in 12 grams of carbon-12 there are exactly the same number of atoms. Both the gram of hydrogen and the 12 grams of carbon-12 have 6.022 x 1023 atoms, despite the fact that the atomic mass of hydrogen is 1 amu (atomic mass unit) and that of carbon-12 is 12 amu.
This is essential for the knowledge experimental of the chemistry. For example, to generate 1 mole of Water (H2O) combine 1 mole of oxygen (6.022 x 1023 atoms) with 2 moles of hydrogen (2 x 6.022 x 1023 atoms). This, of course, according to the measurements accepted by the International system (YES).
History of Avogadro's Number
The discovery of this constant is attributed to Amadeo Avogadro, an Italian scientist of the early 19th century who first proposed in 1811 that a volume of a gas to a certain Pressure Y temperature it contains the same number of atoms or molecules, regardless of the nature of the gas itself.
Avogadro's Number was, however, postulated in 1909 under that name, by the French physicist Jean Perrin, who won the Nobel Prize in Physics in 1926, largely thanks to his efforts to determine the exact value of the Constant of Avogadro using various techniques Y methods experimental.