We explain what the mole is and how this magnitude is calculated. In addition, its general characteristics and what is its volume.

**What is the mole?**

The mole is one of the quantities stipulated by the International System of Units (SI). Its symbol is “mole.”

The mole is defined as the amount of matter that contains a certain number of elementary entities (atoms, molecules, etc.) equivalent to the number of bits in 12 grams of the isotope carbon-12 (12C).

The mass of a mole of a substance (called molar mass) is equivalent to the atomic or molecular mass (depending on whether a mole of atoms or molecules has been considered) expressed in grams.

Avogadro’s number (NA) is the number of particles (molecules, atoms, electrons) contained in one mole of any substance. It is a constant that corresponds to the value of 6.022×10^23 mol-1. Therefore, 1 mole of any importance has 6.022×10^23 elemental entities of that substance. On the other hand, Avogadro’s number establishes conversions between the gram and the atomic mass unit, being 6.022×10^23 AMU (atomic mass unit) equal to 1 gram. Avogadro’s number is the number of atoms contained in 1 mole of atoms whose mass is similar to the nuclear group of the element.

**How is the mole calculated?**

To calculate moles, it is necessary to know the atomic or molecular mass, depending on whether it is atoms or compounds. Then, to calculate the number of moles of molecules or atoms of any substance, the fraction between the mass of the essence over its molecular or atomic mass must be made. For example, if we want to calculate the number of moles of X, we write:

**mole**

Where: is the number of X moles, m(X) is the mass of X, and M(X) is X’s atomic or molecular mass.

What is the volume of a mole?

When substances are in a gaseous state, it is possible to calculate the volume occupied by one mole. The book is a measure of the magnitude of the extension of a body, and its unit is the cubic meter (m3) in SI.

Under average temperature and pressure conditions (T=25⁰C and P=1atm), the volume of one mole of gas equals 22.4 liters (L). This value is called the molar volume (Vm) and corresponds to the so-called ideal gases. Natural gases have values of Vm slightly different from this value. For example, CO2 has Vm=22.3L.

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