Why Avagodro number is 6 022

Amedeo Avogadro Constant and Law

Amedeo Avogadro was a successful Italian physicist and chemist. We deal with his findings - the Avogadro constant - and Avogadro's law in this section. This article belongs to the basics of chemistry.

In this article we looked at Avogadro's constant and Avogadro's law. I will go into the important fundamentals of chemistry again in a moment in order to understand exactly these relationships. However, if you have any major gaps in your previous knowledge, I advise you to read the following articles first:


Avogadro constant

First, a quick reminder: One mole of a substance contains about 6,022 x 10 823 Particle. If you take one mole of oxygen or one mole of copper, you always get 6.022 · 1023 Particles of this substance. A particle is understood to be a core particle, i.e. protons and neutrons together. This was named Avogadro constant N after the Italian physicist and chemist Amadeo AvogadroA. with the unit 1 / mol (spoken: one per mol).

With this number one can convert the atomic mass - given in "u" - into the mass in grams, which is 6.022 · 1023 Own atoms. To achieve this, the Avogadro constant is multiplied by the atomic mass (1u = 1.661 · 10-24 G). The result is called the molar mass. The following examples should make this easier to understand. It is best to open the periodic table of the elements (show periodic table in a new window). There is also the necessary information for the elements, which was also used for the following calculations:

  • Oxygen: 6.02 x 1023 / mol x 16 x 1.661 x 10-24 g = 16 g / mol
  • Copper: 6.02 x 1023 / mol x 63.5 x 1.661 x 10-24 g = 63.5 g / mol

Avogadro's Law

In addition to Avogadro's constant, the so-called Avogadro's law went down in the history of chemistry. It is often also called "Avogadro's Law" or "Avogadro's Theorem". Avogadro's law says in simple terms: The same volume of all gases contains the same number of smallest particles at the same temperature and pressure.

Many people today know the formula for a water molecule: H2O. There used to be the assumption that the formula was just HO. The atomic mass of oxygen would then have been 8u. The law of simple volume ratios opposed this. Experiments showed that two parts of hydrogen and one part of oxygen reacted to two parts of water. The easiest way to understand this is to think of hydrogen and oxygen as molecules (two connected atoms). One molecule of hydrogen reacts with one atom of oxygen to form water.

Not only hydrogen, but also chlorine is in molecular form. If hydrogen (H) is allowed to react with chlorine (Cl), hydrogen chloride (HCl) is obtained. One part of the volume of hydrogen and one part of the chlorine result in one part of the volume of hydrogen chloride. Explanation: Every 1 atom of hydrogen combines with an atom of chlorine. For this reason the formula for hydrogen chloride is H.1Cl1.


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