How to find the equivalent of
It called equivalent particle which is chemically equivalent (equivalent) in an acid-base reactions one hydrogen ion in a redox reaction types - one electron. Equivalent numbers expressed without dimension, whereas the equivalent weight is measured in g / mole.
You will need:
- calculator; - periodic table
Instruction how to find the equivalent of
To be able to find the equivalent of a substance, you should use the formula: 1 / z (a substance), where 1 / z - factor equivalence (fe), that is a number that indicates how much of the particulate matter equivalent equivalent. This value is always less than or equal to one. Simply put, the equivalence factor - a factor which is recorded directly in front of the compound of formula in finding the equivalent. For example, you need to find the equivalent of phosphoric acid in its interaction with the sodium hydroxide. Record reaction equation: 2NaOH + H3PO4 = Na2HPO4 + 2H2OOtsyuda seen that the sodium atoms are replaced by only two hydrogen atoms, that is a dibasic acid (H 2 + ions are involved in the reaction). Thus, by definition, will be equivalent to a conventional phosphoric acid particle ½ H3PO4.
Note that the equivalent of one and the same substance varies with the type of reaction in which the substance enters. Furthermore, equivalent elements depends on the type of compound, which includes. Take the same materials as in the previous case, but the reaction may go in a different way: 3NaOH + H3PO4 = Na 3PO4 + 3H2O.Zdes fe (H3PO4) = 1/3, fe (NaOH) = 1. Therefore, the equivalent of phosphoric acid - particle 1/3 H3PO4, and is equal to one equivalent of alkali.
For successful finding equivalents various substances you need to memorize formulas for finding fe depending on the type of chemical compounds. So much for the simple elements fe = 1 / valence of the element. Example: fe (H2SO4) = 1/6, and the sulfur equivalent is 6. For H2SO4 salts - fe = 1 / n (meth.) - B (meth.) = 1 / n (kp) - B ( kb), wherein n (meth) -. The amount of metal atoms, B (meth) -. valence of the metal, n (kb) - the number of acid residues, B (KO) -. valency acid residue and t .d.
It is more difficult to find an equivalent material in the reactions of the redox type, since the calculation you will lead on the number of electrons that are involved in the reduction or oxidation. Given the task to find the equivalent of manganese hydroxide in the reaction: 2Mn (OH) 2 + 12NaOH + 5Cl2 = 2NaMnO4 + 10NaCl + 8H2OIz equation shows that the manganese electrons and gives 5 passes from Mn +2 in Mn +7. Hence the equivalence factor Mn (OH) 2 - 5.1, and the equivalent of hydroxide is 5.