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Related to equivalent weight: normality
equivalent weight.The equivalent weight of an element or radical is equal to its atomic weightatomic weight,
mean (weighted average) of the masses of all the naturally occurring isotopes of a chemical element, as contrasted with atomic mass, which is the mass of any individual isotope. Although the first atomic weights were calculated at the beginning of the 19th cent.
..... Click the link for more information. or formula weightformula weight,
in chemistry, a quantity computed by multiplying the atomic weight (in atomic mass units) of each element in a formula by the number of atoms of that element present in the formula, and then adding all of these products together.
..... Click the link for more information. divided by the valencevalence,
combining capacity of an atom expressed as the number of single bonds the atom can form or the number of electrons an element gives up or accepts when reacting to form a compound.
..... Click the link for more information. it assumes in compounds. The unit of equivalent weight is the atomic mass unitatomic mass unit
in chemistry and physics, unit defined as exactly 1-12 the mass of an atom of carbon-12, the isotope of carbon with six protons and six neutrons in its nucleus. One amu is equal to approximately 1.66 × 10−24 grams.
..... Click the link for more information. ; the amount of a substance in grams numerically equal to the equivalent weight is called a gram equivalent. Hydrogen has atomic weight 1.008 (rounded to three decimal places) and always assumes valence 1 in compounds, so its equivalent weight is 1.008. Oxygen has an atomic weight of 15.999 and always assumes valence 2 in compounds, so its equivalent weight is 7.9995. The sulfate radical (SO4) has formula weight 96.0636 and always has valence 2 in compounds, so its equivalent weight is 48.0318. Some elements exhibit more than one valence in forming compounds and thus have more than one equivalent weight. Iron (atomic weight 55.845) has an equivalent weight of 27.9225 in ferrous compounds (valence 2) and 18.615 in ferric compounds (valence 3). The weight proportion in which elements or radicals combine to form compounds can be determined from their equivalent weights. For example, hydrogen can combine with oxygen to form water; the weight proportion of oxygen to hydrogen in water is the same as the proportion of their equivalent weights, 7.9995 to 1.008 or 7.936 to 1; there is 1 weight of hydrogen for every 7.936 weights of oxygen, or water is about 11.2% hydrogen (by weight). Iron forms two oxides: ferrous oxide (FeO), in which there are 27.9225 weights of iron for each 7.9995 weights of oxygen, and ferric oxide (Fe2O3), in which there are 18.615 weights of iron for every 7.9995 weights of oxygen.
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equivalent weight[i′kwiv·ə·lənt ′wāt]
The number of parts by weight of an element or compound which will combine with or replace, directly or indirectly, 1.008 parts by weight of hydrogen, 8.00 parts of oxygen, or the equivalent weight of any other element or compound.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.