Semiheavy water
Chemical compound / From Wikipedia, the free encyclopedia
Semiheavy water is the result of replacing one of the protium in light water with deuterium.[1] It exists whenever there is water with light hydrogen (protium, 1H) and deuterium (D or 2H) in the mix. This is because hydrogen atoms (hydrogen-1 and deuterium) are rapidly exchanged between water molecules. Water containing 50% H and 50% D in its hydrogen contains about 50% HDO and 25% each of H2O and D2O, in dynamic equilibrium.[2] In regular water, about 1 molecule in 3,200 is HDO (one hydrogen in 6,400 is D). By comparison, heavy water D2O[3] occurs at a proportion of about 1 molecule in 41 million (i.e., one in 6,4002). This makes semiheavy water far more common than "normal" heavy water.
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Names | |||
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IUPAC name
(O-2H1)Water | |||
Other names
Deuterium hydrogen monoxide Deuterium hydrogen oxide, Water-d1 , Water-d | |||
Identifiers | |||
3D model (JSmol) |
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ChEBI | |||
ChemSpider | |||
115 | |||
PubChem CID |
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CompTox Dashboard (EPA) |
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Properties | |||
H2HO (also HDO) | |||
Molar mass | 19.0214 g mol−1 | ||
Appearance | Very pale blue, transparent liquid, very similar to regular water | ||
Density | 1.054 g cm−3 | ||
Melting point | 3.81 °C (38.86 °F; 276.96 K) | ||
Boiling point | 100.74 °C (213.33 °F; 373.89 K) | ||
miscible | |||
log P | −0.65 | ||
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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The freezing point of semiheavy water is close to the freezing point of heavy water at 3.8°C compared to the 3.82°C of heavy water.