equivalent weight


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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.
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 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.
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 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.
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 it assumes in compounds. The unit of equivalent weight is the atomic mass unitatomic mass unit
or amu,
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.
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; 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.

equivalent weight

[i′kwiv·ə·lənt ′wāt]
(chemistry)
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.
References in periodicals archive ?
Table 1 shows the oligomers made and their theoretical C-H equivalent weights.
A contingency analysis was performed in order to understand the effect of PHMS-PDMS hydride equivalent weight of the starting copolymer on coating film uniformity/integrity.
Stage 3 of the approach used in this study is to apply the derived conversion factors to the published HBS results in order to convert the expenditure data to their equivalent weight or volume.
The term in parentheses can be defined as the concentration-weighted mean equivalent weight ([bar.
New chemical analyses by USDA scientists show that the red part of the watermelon can have about 40 percent more lycopene than an equivalent weight of uncooked tomatoes has.
In its UTTAS specification issued in January 1972, the Army was looking for a robust and dependable aircraft capable of lifting an eleven-man infantry squad, or an equivalent weight in cargo, to medium altitudes at a cruising speed of 201 miles per hour.
According to DuPont, DuraLife has an exclusive slicker that provides low surface friction for greater softness; greater fill power, compared with solid fibers of equivalent weight due to its being a high-void fiber with a helical crimp; and a patented, molded-polyester fiber cluster system that maintains 85 percent to 95 percent of its height after years of use.
CONTRACTORS working at Southwell racecourse are moving the equivalent weight of 530 double-decker buses to bring the all-weather track up to scratch, writes Howard Wright.
The opinion states that, although temporary regulations are to be given equivalent weight as final regulations, regulations issued under Sec.
Among the five strategies used by a majority of respondents, management and employee concerns receive nearly equivalent weight.
To get the right weight to counterbalance the doors, the cylinders were filled with sand and tested, then sand was replaced with an equivalent weight of concrete.