Chemistry is a science of extremes. In the sense that the actual, real, describing the reality of the numbers in it are either extremely small or extremely large. A lot of people would be frightened by a number with 23 zeros. It's really a lot. But there are so many units (pieces) contained in one mole of a substance. Would you like to carry out calculations with such colossal numbers? It is not comfortable. But nowadays, any student solves chemistry problems with a sheet of paper and a simple calculator. This is possible thanks to a special simplification language created by chemists. And one of the main phrases of this language is “molar mass.”
Formula by definition
Determining the molar mass is simple: the mass of a substance should be divided by its chemical quantity. That is, you will find out how much one mole of a given substance weighs. There is another way to determine the molar mass, but the main thing here is not to get confused. The molar mass is numerically equal to the atomic or molecular mass. But the units are different.
Why even?
When would 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 ratios. If you know the actual quantities of substances, you can calculate the kind of atoms and their proportions in the substance. And you will need the help of an old chemist. Really very old. Mendeleev himself.
Connections of concepts
How can the table of the great scientist help us? The molar mass of a substance is equal in number to the atomic (for atomic substances and pure metals) or molecular mass, but is measured in other units. This characteristic of a substance will be indicated in grams per mole, molecular - in atomic mass units. How is it that these numbers are the same? Those values that you see in the table for the elements were calculated empirically. Each kind of atom was weighed and its mass determined in convenient units. Therefore, you see not a minus twenty-seventh degree, but quite decent numbers, most often within one and a hundred. There are also heavyweight elements, but they are usually not mentioned in school problem books.
If not all the numbers are at hand
What if the substance is made up of molecules and you know what it is? How is the molar mass of a substance searched for if its mass and chemical quantity are not available simultaneously according to the conditions of the problem? It's simple, find each kind of atom (element) in the table andmultiply atomic masses by the number of atoms in a molecule for different elements. And then you just sum it up - and you get the molecular weight, which will exactly match the molar mass. Everything is already prepared for modern young chemists - for a known formula of a substance, it is not a problem to calculate the desired value.
If you understand the essence of chemistry, it will seem very easy to you. The main load in the development of this science is to study and memorize the properties of specific substances, but the general processes and descriptions are nowhere easier. Once you understand, practice - you will never get confused in your life.
