Some chemical tasks demand performance of standard actions therefore their knowledge often is useful. The algorithm of finding of amount of substance is rather simple, it can be useful for simplification of the course of the decision.
Instruction
1. Define for yourself that as the theoretical concept represents amount of substance. This number shows that quantity of structural elements which enter this substance. At the same time as structural particles are considered both atoms and a molecule, and protons, electrons, etc. Understanding will allow you to understand quicker that in this task it will be useful to calculate amount of substance.
2. Remember the main unit of expression of amount of substance – mol. 1 Mol is such amount of substance which contains the number of particles equal to amount of atoms in the 12th of carbon nuclide gram. This quantity carries constant Avogadro's name: for calculations you will need to know its approximate value: 6.022*1023.
3. Get acquainted also with one more concept which will be required to you for calculation of amount of substance: it is molar weight, or the mass of one of separate atom of an element. Already from definition it is noticeable that it is measured in g/mol. Use the standard table which contains values of molar weight for some elements.
4. Apply a formula to finding of amount of substance: n = m/M where n is required size, m is its weight, and M – molar weight. The task can contain data on the molecular weight representing the mass of one molecule expressed in atomic unit of mass. In this case for finding of molar weight you will need to increase this number by constant Avogadro.
5. Use a formula for calculation of amount of substance for gaseous substances if in a task the corresponding conditions are shown. In this case you need to operate not with a weight, and with a volume of an initial element, and instead of molar weight use the molar volume of gas under normal conditions (2.24 l/mol).