How to determine the equivalent substances

The equivalentprobability weight is one of the most important characteristics of substances. When solving problems it is denoted as M EQ. Is determined by the molar equivalent weight of any compound, the chemical formula of the studied substances and its belonging to a particular class of chemical compounds.

In order to find the molar mass equivalents, you'll need to know such factors as molar mass – the mass of one mole of a substance. The basicity of acids the number of hydrogen atoms that the acid can attach. The acidity of the base is determined by the number of OH-ions. Valence – the number of chemical bonds that an atom forms with other elements in the mix.

The formula for finding the equivalent mass of a substance depends on what class applies the test compound. For example, for finding the equivalent substances of the oxides, you will need to divide molar mass of compound by the number of oxygen atoms, is pre-multiplied by two. For example, for Fe2O3 equivalent weight is equal to 56*2 + 16*3/3*2 = 26,7 g/mol.

To find the molar mass of the equivalent substances at the base, divide the molar mass of the base in its acidity. So, for the base Ca(OH)2 equivalent will be equal to 40 + (16+2)*2/2 = 37 g/mol.

To find equivalent substances for the acid, you will need to do the following: divide the molar mass of the acid is its basicity. To find the molar mass of equivalent of the substance sulfuric acid, H2SO4 divide 1*2 + 32 + 16*4/2 = 49 g/mol.

Finally, to find equivalent substances of salt, divide the molar mass of the substance by the number of metal atoms, multiplied by its valence. For example, the molar mass equivalent substances salts Al2(SO4)3 = 27*2 + (32 + 16*4)*3/1*2 = 171 g/mol.