The mass of one mole of a given substance is called molar mass.
The physical magnitude that indicates the amount of matter present in a body is called mass . The term, which comes from the Latin massa , has as a unit in the International System the kilogram ( kg. ).
The notion of molar mass refers to the mass of one mole of a certain substance, expressed in grams. A mole, on the other hand, is the amount of substance that contains as many elemental entities (atoms, molecules, ions, etc.) of one type as there are atoms present in 12 grams of carbon-12 .
The number of elementary units indicated by one mole of substance, therefore, is constant, since it does not depend on the type of material or particle. This quantity is known as Avogadro's number . This constant allows chemists to express the weight of atoms. The equation indicates that one mole is equivalent to 6.022 x 10 to the power of 23 particles .
What is molar mass
Molar mass, in short, expresses the mass of one mole in grams . If the molecular mass of a substance in amu is p , the molar mass of said substance will also be p , but expressed in grams.
To calculate the molar mass, you must use the periodic table of elements. If we take the case of water ( H2O ), we will see that a molecule is composed of two hydrogen atoms and one oxygen atom. The atomic mass of hydrogen, removing decimals, is 1 amu and that of oxygen is 16 amu . By adding these data of 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 .
The molar mass of water is 18 grams.
Molecular weight concept
Molecular weight (abbreviated as MW ) is what relative molar mass was formerly called, the name it currently receives. It is a dimensionless magnitude (that is not associated with a physical dimension ) 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.
One should 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 reasons of convenience when performing calculations, but in no case are they interchangeable data.
Each element has a different molar mass
Each substance has a unique molar mass, which is numerically equal to its atomic mass, although the latter is expressed in amu , 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 represents a mole is very large; For example, while a dozen apples could be ideal for twelve people to eat fruit after lunch, one mole of apples has an approximate volume of 30 million that of all the oceans on our planet .
In chemistry, the use of the mole is intended to calculate the number of molecules and atoms in a given substance, given that these are extremely small elements. In just one drop of water there are so many molecules of H2O that most people would not know how to express the quantity , and that is why the concept of mole is so useful in these cases, to avoid magnitudes with millions, billions, trillions, etc.