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Chemistry
Chemistry: General
formula weight

formula 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. For example, the formula weight of water (H 2 O) is two times the atomic weight of hydrogen plus one times the atomic weight of oxygen. Numerically, this is (2×1.00797)+(1×15.9994)=2.01594+15.9994=18.01534. If the formula used in computing the formula weight is the molecular formula, the formula weight computed is the molecular weight . The percentage by weight of any atom or group of atoms in a compound can be computed by dividing the total weight of the atom (or group of atoms) in the formula by the formula weight and multiplying by 100. For example, the weight percentage of hydrogen in water is determined by taking two times the atomic weight of hydrogen, dividing it by the formula weight of water, and multiplying by 100. Numerically, this is 100×(2×1.00797)/18.01534=11.19% hydrogen in water by weight. Formula weights are especially useful in determining the relative weights of reagents and products in a chemical reaction. For example, it is known that two molecules of hydrogen gas, H 2 , react with one molecule of oxygen gas, O 2 , to form two molecules of water, H 2 O. This reaction may be represented by the chemical equation 2H 2 +O 2 →2H 2 O. The formula weight of hydrogen gas is 2.01594,...

form. wt

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views updated May 14 2018

form. wt Chem. formula weight

The Oxford Dictionary of Abbreviations FRAN ALEXANDER , PETER BLAIR , JOHN DAINTITH , ALICE GRANDISON , VALERIE ILLINGWORTH , ELIZABETH MARTIN , ANNE STIBBS , JUDY PEARSALL , and SARA TULLOCH

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FRAN ALEXANDER , PETER BLAIR , JOHN DAINTITH , ALICE GRANDISON , VALERIE ILLINGWORTH , ELIZABETH MARTIN , ANNE STIBBS , JUDY PEARSALL , and SARA TULLOCH "form. wt ." The Oxford Dictionary of Abbreviations. . Encyclopedia.com. 27 Nov. 2024 <https://www.encyclopedia.com>.

FRAN ALEXANDER , PETER BLAIR , JOHN DAINTITH , ALICE GRANDISON , VALERIE ILLINGWORTH , ELIZABETH MARTIN , ANNE STIBBS , JUDY PEARSALL , and SARA TULLOCH "form. wt ." The Oxford Dictionary of Abbreviations. . Retrieved November 27, 2024 from Encyclopedia.com: https://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/form-wt

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