Introduction:

Mole, or gram atom for short, is one of the seven basic units of the international system of units, and the symbol is mol. Every 1 mole of any substance (micro-substance, such as molecules and atoms) contains Avogadro constant (about 6.02× 10? ) particles. When using moles, you should specify basic particles, which can be atoms, molecules, ions and other particles, or a specific combination of these particles.

Development history:

Moore is the seventh basic unit of the International System of Units (SI), which was joined by 14 International Metrology Conference in June 1974 and 4 1 countries. Mole is used to calculate the number of particles, the mass of matter, the volume of gas, the concentration of solution, the change of heat during the reaction and so on. Moore comes from the Latin moles, which means to accumulate a lot.

1974 The 14th International Metrology Conference has the following two provisions on the definition of mole: "Mole is the amount of substance in a system, and the number of basic units contained in this system is equal to the number of atoms of 0.0 12kg carbon-12." "When using moles, you should specify the basic unit, which can be atoms, molecules, ions, electrons and other particles, or a specific combination of these particles." The last two paragraphs should be regarded as a whole. The number of carbon atoms in 0.0 12kg carbon-12 nuclide is Avogadro constant (NA). At present, the approximate value measured in the experiment is NA=6.02× 10? . Mole is different from ordinary units. It has two characteristics: ① The basic units for measuring micro, such as molecules and ions, cannot be used to measure macro-substances. (2) it takes Avon Gadereau number as the unit of measurement, and it is a batch, not a number, to measure the number of particles such as molecules and atoms. It can also be used to measure the specific combination of microscopic particles. For example, the amount of sulfuric acid is measured by moles, that is, 1mol sulfuric acid contains 6.02× 10? One molecule of sulfuric acid. Molar is the most widely used unit of measurement in chemistry, such as calculation of chemical reaction equation, calculation in solution, preparation and dilution of solution, calculation of chemical equilibrium, molar volume of gas, thermochemistry and so on.