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 ?
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.
It signals when more than five million purple crocus bulbs, the equivalent weight of two red London double deck buses, will be planted to highlight Rotary's Thanks for Life - End Polio Now campaign in February.
Calorifically, they aren't even that indulgent when compared with their equivalent weight in foods more fashionable with London's cravated fops such as the avocado or the olive (I've got the figures somewhere).
5 tonnes of composite armour -said to be three times as effective as the equivalent weight of steel.
In 2009, Cadbury selection boxes will see a 31 per cent reduction in packaging per unit compared to 2008, saving approximately 400 tonnes of carton board which is the equivalent weight to 73 African elephants.
It claims its Choxi+ chocolate contains two or three times more antioxidants than the equivalent weight of other chocolate bars and can help maintain healthy blood pressure and cholesterol levels.
In all three cases, very good to excellent correlations were found between continuous real-time DES output and the values of characteristic QC parameters (viscosity, acid number, epoxy equivalent weight, % NCO, ATR-FTIR peak heights for reactants and products, and GPC data) determined by off-line analysis of samples taken periodically during the reactions.
In addition to its pilot, the spacecraft had to carry the equivalent weight of two passengers.
The equivalent weight (EW) of the polymer is the mass of the sulfonic acid form required to neutralize one mole of base.
Thomas Gravesen and Kevin Campbell alone look like they've lost the equivalent weight of a family of four.
The plastics currently in airplane cabins have an overall fire potential comparable to that of an equivalent weight of aviation fuel.
The new Ingeo([TM]) production technology also consumes 56 percent less energy than the equivalent weight of PET.