heavy water

n. Either of two isotopic forms of water, especially deuterium oxide, consisting chiefly of molecules that contain deuterium instead of protium. Heavy water is used as a moderator in certain nuclear reactors.

heavy water

n (Elements & Compounds) water that has been electrolytically decomposed to enrich it in the deuterium isotope in the form HDO or D2O

heav′y wa′ter

n. water in which hydrogen atoms have been replaced by deuterium, used as a nuclear reactor coolant. [1930–35]

heavy water

Water formed of oxygen and deuterium. Heavy water is much like ordinary water but has higher freezing and boiling points. It is used in certain nuclear reactors for cooling.Did You Know? How can one drop of water be heavier than another? The answer lies at the atomic level. Normal hydrogen has a nucleus consisting entirely of one proton, around which whirls one electron. However, in a variety of hydrogen called heavy hydrogen or deuterium, a neutron accompanies the proton in the nucleus. Deuterium thus weighs about twice as much as standard hydrogen. The substance we call heavy water is H₂O in which many of the hydrogen atoms are replaced by deuterium. Heavy water played a part in the development of the atomic bomb during World War II. It is an excellent absorber of the neutrons that are produced in large quantities in a nuclear chain reaction. It therefore provided a means of regulating the reactions so that they could be studied safely. Once it was shown that a controlled chain reaction was possible, making a device that could create a powerful uncontrolled chain reaction—an atomic bomb—seemed within reach. Heavy water is still found today in nuclear power plants that use natural uranium fuel.

Thesaurus

Noun

heavy water - water containing a substantial proportion of deuterium atoms, used in nuclear reactorsdeuterium oxidemoderator - any substance used to slow down neutrons in nuclear reactors

Translations

heavy water

heavy water:

see deuteriumdeuterium
, isotope of hydrogen with mass no. 2. The deuterium nucleus, called a deuteron, contains one proton and one neutron. Deuterium is also called heavy hydrogen, and water in which the hydrogen atoms are deuterium is called heavy water (deuterium oxide, D₂O).
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Heavy Water

D₂O, an isotopic species of water in which the light hydrogen atom ¹H is replaced by its heavy isotope ²H, which is called deuterium (D).

Heavy water was first discovered in natural water by H. Urey and E. F. Osborn (USA) in 1932; the species was isolated by G. N. Lewis and R. MacDonald (USA) in 1933. The density of heavy water is greater than that of ordinary water, hence the name. Heavy water is found in natural water and in atmospheric precipitation in the ratio of one D atom to 5,000–7,000 H atoms. The techniques of mass spectrometry, densimetry, and infrared spectroscopy are used in determining the content of heavy water.

The physical properties of D₂O differ markedly from those of H₂O. Heavy water boils at 101.43°C and freezes at 3.82°C; its density is 1.104 g/cm³. The chemical properties of heavy water are very close to those of H₂O, although certain reactions occurring in a D₂O medium are retarded or accelerated, sometimes by a factor between 2 and 3. The principal industrial methods for producing heavy water are the isotopic exchange of water and hydrogen sulfide, the distillation of hydrogen, and multistep electrolysis.

Heavy water is used in nuclear physics and power engineering as a neutron moderator and heat-transfer agent in nuclear reactors; it also serves as a starting material in the production of deuterium. Heavy water is used in chemistry, biology, and hydrology as an isotope tracer. In organisms, even a small amount of heavy water has an inhibitory effect, while larger doses are lethal.

The term “heavy water” is also used for water containing heavy oxygen, where ¹⁶O has been replaced by the heavy isotopes ¹⁷O and ¹⁸O. It likewise applies to HDO, to tritiated water (T₂O), and to HTO and DTO. In superheavy water, ‘H is replaced by the radioisotope ³H, known as tritium (T).

REFERENCES

Kirshenbaum, I. Tiazhelaia voda. Moscow, 1953. (Translated from English.)
Kirshenbaum, I. Proizvodstvo tiazheloi vody. Moscow, 1961. (Translated from English.)
Kratkaia khimicheskaia entsiklopediia, vol. 1. Moscow, 1961. Pages 614–17.
Brodskii, A. I. Khimiia izotopov, 2nd ed. Moscow, 1957.

V. S. PARBUZIN

heavy water

[′hev·ē ′wȯd·ər] (inorganic chemistry) A compound of hydrogen and oxygen containing a higher proportion of the hydrogen isotope deuterium than does naturally occurring water. Also known as deuterium oxide.

heavy water

water that has been electrolytically decomposed to enrich it in the deuterium isotope in the form HDO or D₂O

heavy water

heav·y wa·ter

D₂O; water in which the hydrogen atoms are deuterium, or heavy hydrogen (²H), with physical properties that differ noticeably from those of ordinary water; an elevated presence will cause a decrease in metabolic activity; used as a moderator in nuclear reactors because of its capacity to absorb neutrons. Synonym(s): deuterium oxide

heavy water

D₂O; an isotopic variety of water, esp. deuterium oxide, in which hydrogen has been displaced by its isotope, deuterium. Its properties differ from ordinary water in that heavy water has a higher freezing and boiling point and does not support life. See also: water

heavy water

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heavy water:

Heavy Water

REFERENCES

heavy water

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heav·y wa·ter

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Synonyms for heavy water

noun water containing a substantial proportion of deuterium atoms, used in nuclear reactors

Synonyms

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