Molar massThe physical quantity that indicates the amount of subject present in a body receives the name of dough. The term, which comes from the Latin mass, has as a unit in the International system to the kilogram (kg.).

The notion of molar mass refers to the mass of a mole of a certain substance, expressed in grams. A mole, on the other hand, is the amount of substance that contains as many elementary entities (atoms, molecules, ions, etc.) of a type as atoms present in 12 grams of carbon-12.

The number of elementary units that indicates a mole of substance, therefore, is constant, since it does not depend on the type of material or particle. That amount is known as Avogadro’s number. This constant allows chemists to express the weight of the atoms. The equation indicates that one mole is equal to 6.022 x 10 to the 23rd power.

The molar mass, in short, expresses the mass of a mole in grams. If the molecular mass of a substance in uma it is p, the molar mass of that substance will also be p, but expressed in grams.

To calculate the molar mass, one must resort to the periodic table Of elements. If we take the case of water (H2O), we will see that a molecule is made up of two hydrogen atoms and one oxygen atom. The atomic mass of hydrogen, minus decimals, is 1 amu and that of oxygen, 16 amu. By adding these data for the two hydrogen atoms and the oxygen atom, we obtain a molecular mass of 18 grams. The molar mass of water, therefore, is also 18 grams.

Molar massThe molecular weight (abbreviated as P.M) is how the relative molar mass, the name it currently receives. It is a dimensionless quantity (which is not associated with a dimension physics) equal to the result of dividing the molar mass by the molar mass constant, which relates the molar mass and the atomic weight. Technically, the relative molar mass is derived from measuring the molar mass on a scale in which the value of an unbonded carbon-12 atom, in its ground state and at rest is 12.

Do not make the mistake of thinking that molecular weight and molar mass are equivalent concepts; Their similarity in terms of numerical values ​​is used for convenience in calculating, but in no case are data interchangeable.

Each substance has a unique molar mass, which is numerically equal to its atomic mass, although the latter is expressed in uma, and this information is found in the periodic table. The reason that each element has a different molar mass is that its atoms have a different number of electrons, protons and neutrons, which affects their atomic masses.

It is important to understand that the number that a mole represents is very large; For example, while a dozen apples might be ideal for twelve people to eat fruit after lunch, a mole of apples has an approximate volume of 30 million that of all the oceans in our world. planet.

In chemistry, the use of the mole is intended to calculate the number of molecules and atoms in a given substance, since they are elements of an extremely small size. In just one drop of water there are so many molecules of H2O that most people would not know how to express the amount, and that is why the concept of mole is so useful in these cases, to avoid magnitudes with millions, billions, trillions, and so on.