First, we should remember a few simple rules.If it is a metal, its equivalent weight is calculated as follows: Mae = M / V, where M - the atomic mass of metal , and B - its valence.Consider this rule to specific examples.
Calcium (Ca).Its atomic weight 40.08.Rounded take it for 40. The valence is 2. Therefore, Mae (Ca) = 40/2 = 20 g / mol.Aluminum (Al).Its atomic weight 26.98.(Rounding 27).Valency is 3. Thus, Mae (Al) = 27/3 = 9 g / mol.
These methods are applicable, if it is a pure metal 's.And if they are part of a compound, such as oxides of the same?Here we must remember another rule: the equivalent weight oxide is calculated as follows: + Mae Mo, where Mo - equivalent weight of oxygen.It is, accordingly, calculated according to the formula already considered the M / B, ie 16/2 = 8.
Suppose you have a basic aluminum oxide, Al2O3.How to calculate its equivalent weight?Very simple: 27/3 + 16/2 = 17 g / mol.
Is there any other way to determine the equivalent weight metal and oxide ?Yes, and very effective.It is based on the so-called law equivalents, whereby all substances react with each other in equivalent amounts.For example, the metal mass of 33.4 grams reacted oxidation with atmospheric oxygen.The result is an oxide of a total weight of 43 grams.It is required to determine the equivalent weight of metal and oxide .
first calculate how much oxygen is united with the metal in the course of the reaction: 43 - 33.4 = 9.6 grams.According to the law of equivalents, the weight as many times more than the equivalent weight oxygen (which, recall, is 8), how many times the equivalent weight of metal less than the original amount.That is 33.4 / Mae (IU) = 9.6 / 8.Consequently, Mae (IU) = 33.4 * 8 / 9.6 = 27.833 g / mol, or rounded 27.8 g / mole.This is the equivalent weight of metal .
The equivalent weight of the oxide find the following: 27.8 + 8 = 35.8 g / mol.