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For example, in HBr with one mole of atoms of Hydrogen, 1 mole of

Bromium atoms is combined, so the equivalent of Brom in this compound is equal

to one mole of Brom atom and its equivalent mass is 80 g/mol-eq.

In H 2O one mole of Hydrogen atoms there is connected 1/2 mole of Oxygen

atoms, so the equivalent of Oxygen in this compound is equal to 1/2 mole of

Oxygen atoms, and its equivalent weight is equal to 16/2 = 8 g/mol-eq.

So, it is clear that in chemical reactions of various individual substances

involved in strictly equivalent amounts. This statement is the basis of the law of

equivalents:

=

Equivalent masses of elements are determined by the formula

E =
el

where M - is the molar mass of the element;

V - is the valency element.

For example, E (Al) = 27/3 = 9 g/mol-eq. Equivalent masses of complex

substances are determined by the following formulas.

Equivalent mass of acid:

E acid =

The basicity of acid is determined by the amount of Hydrogen cations in the

acid molecule, which can be replaced by cations of the metal.

Equivalent weight of the base:

E bases =

The acidity of the base is determined by the number of hydroxyl groups in the

base molecule, which are replaced by acid residues.

Equivalent mass of salt:

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