Molar mass? Table to help!

Chemistry is the science of extremes. In the sense that actual, real, numbers describing the reality in it are either extremely small or extremely large. Many would be frightened by a number with 23 zeros. This is really a lot. But in fact so many units (pieces) are contained in one mole of substance. Would you like to conduct calculations with such colossal numbers? It is not comfortable. But in our time any schoolboy solves problems in chemistry with a sheet of paper and a simple calculator. This is possible thanks to a special language of simplification, created by chemists. And one of the main word combinations of this language is the "molar mass".

The formula by definition

Determine the molar mass simply: the mass of the substance should be divided into its chemical quantity. That is, you will know how much one mole of this substance weighs. There is another way to determine the molar mass, but here the main thing is not to get confused. The molar mass is equal numerically to the atomic or molecular mass. But the units of measurement are different.

But in general, why?

In what situations might you need a molar mass? A classic example is the need to identify the formula of a substance. Not all substances and not in all situations can be determined by chemical properties and appearance, sometimes it is necessary to consider quantitative relationships. If you know the actual quantities of substances, you can calculate the type of atoms and their proportions in the substance. And you will need the help of an old chemist. Really very old. Mendeleyev himself.

Concept links

How will the table of the great scientist help us? The molar mass of the substance is equal in number to the atomic mass (for atomic substances and pure metals) or molecular weight, but is measured in other units. This characteristic of the substance will be in grams per mole, molecular - in atomic units of mass. How did it happen that these numbers are the same? The values that you see in the table for the elements have been calculated empirically. Each type of atoms could be weighed and its mass determined in convenient units. So you see not a minus the twenty-seventh degree, but quite decent numbers, most often within a unit and a hundred. There are also heavyweight elements, but they are usually not mentioned in school book problems.

If not all numbers are at hand

And what if the substance consists of molecules and you know what it is? How is the molar mass of a substance sought if there is no mass of it and a chemical quantity simultaneously under the conditions of the problem? It's simple, find each kind of atom (element) in the table and multiply the atomic masses by the number of atoms in the molecule for different elements. And then simply summarize - and get a molecular mass that will perfectly match the molar mass. For modern young chemists, everything is already prepared - for the known formula of the substance, the desired value to calculate is not a problem.

If you understand the essence of chemistry, it will seem very easy for you. The main burden in mastering this science is to study and memorize the properties of specific substances, but the general processes and descriptions are simply nowhere else. Once you understand, you will practice - you will never get lost in life.