The relative molecular mass of substance (or simply - molecular weight) is the relation of value of mass of this substance to 1/12 mass of one atom of carbon (C). To find relative molecular weight very easily.
It is required to you
- Mendeleyev's table and table of molecular masses
Instruction
1. The relative molecular mass of substance is the sum of its atomic masses. To learn the atomic mass of any given chemical element, it is enough to look at Mendeleyev's table. It can be found on a cover of any textbook in chemistry, or to get separately in bookstore. The pocket option, or a leaf of A4 format quite will be suitable for the school student. Any modern office of chemistry is equipped with the full-scale wall table of Mendeleyev.
2. Having learned the atomic mass of an element, it is possible to start calculation and the molecular mass of substance. It is the simplest to show it on an example: It is required to calculate the molecular mass of water (H2O). From a molecular formula it is visible that the molecule of water consists of two atoms of hydrogen H and one atom of oxygen O. Therefore calculation of molecular mass of water can be reduced to action: 1.008*2 + 16 = 18.016
3. Besides the way stated above, given about a molecular lot of some chemical compounds it is possible to emphasize from the table of molecular masses.