- heavy water
water in which hydrogen atoms have been replaced by deuterium, used chiefly as a coolant in nuclear reactors. Also called deuterium oxide.[1930-35]
* * *Water composed of two atoms of deuterium (D; a heavy isotope of hydrogen) and one atom of oxygen (O), chemical formula D2O. Water from most natural sources contains about 0.015% deuterium oxide; this can be enriched or purified by distillation, electrolysis, or chemical processing. Heavy water is used as a moderator in nuclear power plants, slowing down the fast neutrons so that they can react with the fuel in the reactor. Heavy water is also used in research as an isotopic tracer for chemical reactions and biochemical pathways. Water with tritium (T2O) rather than deuterium may also be called heavy water.
* * *(D2O),also called Deuterium Oxide,water composed of deuterium, the hydrogen (q.v.) isotope with a mass double that of ordinary hydrogen, and oxygen. (Ordinary water has a composition represented by H2O.) Thus, heavy water has a molecular weight of about 20 (the sum of twice the atomic weight of deuterium, which is 2, plus the atomic weight of oxygen, which is 16), whereas ordinary water has a molecular weight of about 18 (twice the atomic weight of ordinary hydrogen, which is 1, plus oxygen, which is 16).Ordinary water as obtained from most natural sources contains about one deuterium atom for every 6,760 ordinary hydrogen atoms. If water is electrolyzed the gas produced at the cathode is mostly hydrogen, and thus the residual water is enriched in deuterium content. Continued electrolysis of hundreds of litres of water until only a few millilitres remain yields practically pure deuterium oxide. This operation, until 1943 the only large-scale method used, has been superseded by less expensive processes, such as fractional distillation (D2O becomes concentrated in the liquid residue because it is less volatile than H2O). The heavy water produced is used as a moderator of neutrons in nuclear power plants. In the laboratory heavy water is employed as an isotopic tracer in studies of chemical and biochemical processes.
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Heavy water — Water containing a significantly greater proportion of heavy hydrogen (deuterium) atoms to ordinary hydrogen atoms than is found in ordinary (light) water. Heavy water is used as a moderator in some reactors because it slows neutrons… … Energy terms
heavy water — n. water composed of heavy isotopes of hydrogen or oxygen, or of both; esp., deuterium oxide, D2O, which is water composed of ordinary oxygen and deuterium … English World dictionary
heavy water — n 1) the compound D2O composed of deuterium and oxygen called also deuterium oxide 2) water having a higher than usual proportion of deuterium among its hydrogen atoms * * * a compound analogous to water but containing deuterium, the mass two… … Medical dictionary
Heavy water — См. Тяжелая вода Термины атомной энергетики. Концерн Росэнергоатом, 2010 … Термины атомной энергетики
Heavy water — Not to be confused with hard water or tritiated water. Deuterium oxide IUPAC name … Wikipedia
heavy water — noun water containing a substantial proportion of deuterium atoms, used in nuclear reactors • Syn: ↑deuterium oxide • Hypernyms: ↑moderator * * * ˈheavy water 7 [heavy water] noun … Useful english dictionary
heavy water — sunkusis vanduo statusas T sritis chemija formulė D₂O atitikmenys: angl. heavy water rus. тяжелая вода … Chemijos terminų aiškinamasis žodynas
heavy water — sunkusis vanduo statusas T sritis fizika atitikmenys: angl. heavy water vok. schweres Wasser, n; Schwerwasser, n rus. тяжёлая вода, f pranc. eau lourde, f … Fizikos terminų žodynas
heavy water — sunkusis vanduo statusas T sritis apsauga nuo naikinimo priemonių apibrėžtis D₂o, vanduo, kuriame vietoje paprastų vandenilio atomų yra sunkieji vandenilio izotopai – deuterio atomai. Sunkiojo vandens tankis 1,104 g/cm³, lydymosi temperatūra… … Apsaugos nuo naikinimo priemonių enciklopedinis žodynas
heavy water — sunkusis vanduo statusas T sritis ekologija ir aplinkotyra apibrėžtis Deuterio oksidas (D₂O) – bespalvis skystis, kuriame vietoje paprastų vandenilio atomų yra sunkieji vandenilio izotopai – deuterio atomai. Jame lėčiau vyksta cheminės reakcijos … Ekologijos terminų aiškinamasis žodynas