- Chem.the combining power, esp. in grams (gram equivalent), of an element or compound, equivalent to hydrogen as a standard of 1.00797 or oxygen as a standard of 8; the atomic weight divided by the valence.[1925-30]
* * *Quantity of an element that exactly reacts with (equals the combining value of) 1 g of hydrogen, 8 g of oxygen, or a corresponding amount of any other element.An element's equivalent weight is its atomic weight divided by its valence. In general, for oxidation-reduction, including electrolysis, the equivalent weight is the weight associated with the loss or gain of 6.02 × 1023 electrons (Avogadro's number) or 96,500 coulombs of electric charge; this is also the molecular weight divided by the number of electrons lost or gained. The equivalent weight of a substance with several valences differs depending on the number of electrons transferred in the given reaction. The number of equivalent weights of any substance dissolved in one litre of solution is called the solution's normality (N). See also stoichiometry.
* * *in chemistry, the quantity of a substance that exactly reacts with, or is equal to the combining value of, an arbitrarily fixed quantity of another substance in a particular reaction. Substances react with each other in stoichiometric, or chemically equivalent, proportions, and a common standard has been adopted. For an element the equivalent weight is the quantity that combines with or replaces 1.00797 grams (g) of hydrogen or 7.9997 g of oxygen; or, the weight of an element that is liberated in an electrolysis (chemical reaction caused by an electric current) by the passage of 96,500 coulombs of electricity. The equivalent weight of an element is its gram atomic weight divided by its valence (combining power). Some equivalent weights are: silver (Ag), 107.868 g; magnesium (Mg), 24.312/2 g; aluminum (Al), 26.9815/3 g; sulfur (S, in forming a sulfide), 32.064/2 g. For compounds that function as oxidizing or reducing agents (compounds that act as acceptors or donors of electrons), the equivalent weight is the gram molecular weight divided by the number of electrons lost or gained by each molecule; e.g., potassium permanganate (KMnO4) in acid solution, 158.038/5 g; potassium dichromate (K2Cr2O7), 294.192/6 g; and sodium thiosulfate (Na2S2O3·5H2O), 248.1828/1 g. For all oxidizing and reducing agents (elements or compounds) the equivalent weight is the weight of the substance that is associated with the loss or gain of 6.023 × 1023 electrons. The equivalent weight of an acid or base for neutralization reactions or of any other compound that acts by double decomposition is the quantity of the compound that will furnish or react with or be equivalent to 1.00797 g of hydrogen ion or 17.0074 g of hydroxide ion; e.g., hydrochloric acid (HCl), 36.461 g; sulfuric acid (H2SO4), 98.078/2 g; sodium hydroxide (NaOH), 74.09/2 g; sodium carbonate (Na2CO3), 105.9892/ 2 g.The equivalent weight of a substance may vary with the type of reaction it undergoes. Thus, potassium permanganate reacting by double decomposition has an equivalent weight equal to its gram molecular weight, 158.038/1 g; as an oxidizing agent under different circumstances it may be reduced to the manganate ion (MnO42-), to manganese dioxide (MnO2), or to the manganous ion (Mn2+), with the equivalent weights of 158.038/1 g, 158.038/3 g, and 158.038/5 g, respectively. The number of equivalent weights of any substance dissolved in one litre of solution is called the normality of that solution.
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Equivalent weight — is the amount of an element that reacts, or is involved in reaction with, 1 mole of electrons. It is defined by many texts as the weight of the element combining with 1 g hydrogen, 8 g oxygen or 35.5 g chlorine, each of which would either provide … Wikipedia
equivalent weight — n EQUIVALENT (1) * * * the amount of a substance that combines with or displaces 8.0 g of oxygen (or 1.008 g of hydrogen), usually expressed in grams; for acid base reactions, one equivalent donates or receives a mole of protons, and the… … Medical dictionary
equivalent weight — noun the atomic weight of an element that has the same combining capacity as a given weight of another element; the standard is 8 for oxygen • Syn: ↑equivalent, ↑combining weight, ↑eq • Hypernyms: ↑atomic mass, ↑atomic weight, ↑relative atomic… … Useful english dictionary
equivalent weight — noun The atomic weight of an element or radical divided by its valence; the molecular weight of a compound divided by its combining power in a specific reaction. In the proportion d : p :: 1 : v, as a … Wiktionary
equivalent weight — ekvivalentų molio masė statusas T sritis Standartizacija ir metrologija apibrėžtis Medžiagos molio masės ir ekvivalentinio daugiklio sandauga. atitikmenys: angl. equivalent weight; molar mass of equivalents rus. мольная масса эквивалентов, f;… … Penkiakalbis aiškinamasis metrologijos terminų žodynas
equivalent weight — ekvivalentų molinė masė statusas T sritis chemija apibrėžtis Medžiagos molinės masės ir ekvivalentinio daugiklio sandauga. atitikmenys: angl. equivalent weight; molar mass of equivalents rus. мольная масса эквивалентов … Chemijos terminų aiškinamasis žodynas
equivalent weight — equiv′alent weight′ n. chem. the combining power, esp. in grams (gram equivalent), of an element or compound, equivalent to hydrogen as a standard of 1.00797 or oxygen as a standard of 8; the atomic weight divided by the valence. • Etymology:… … From formal English to slang
equivalent weight — noun Date: circa 1855 the mass of a substance especially in grams that combines with or is chemically equivalent to eight grams of oxygen or one gram of hydrogen ; the atomic or molecular weight divided by the valence … New Collegiate Dictionary
equivalent weight — /əˌkwɪvələnt ˈweɪt/ (say uh.kwivuhluhnt wayt) noun Chemistry Obsolete the weight of an element or compound which will combine with, or replace, 1.007 97 grams of hydrogen or 8 grams of oxygen; for an element, the atomic weight divided by the… … Australian English dictionary
equivalent weight — see equivalent … Dictionary of units of measurement