Chemistry:Semiheavy water

Short description: Chemical compound

Semiheavy water

Names
IUPAC name (O-2H1)Water
Other names Deuterium hydrogen monoxide Deuterium hydrogen oxide, Water-d1 , Water-d
Identifiers
CAS Number	14940-63-7
3D model (JSmol)	Interactive image
ChEBI	CHEBI:33806
ChemSpider	123344
Gmelin Reference	115
PubChem CID	139859
InChI InChI=1S/H2O/h1H2/i/hD Key: XLYOFNOQVPJJNP-DYCDLGHISA-N
SMILES [2H]O
Properties
Chemical formula	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)
Solubility in water	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).
N verify (what is YN ?)
Infobox references

Tracking categories (test):

• PairSizeSet

Semiheavy water is the result of replacing one of the protium in light water with deuterium. 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. In regular water, about 1 molecule in 3,200 is HDO (one hydrogen in 6,400 is D). By comparison, heavy water D₂O 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.

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.

Further reading

• "Energy relaxation versus spectral diffusion of the OH-stretching vibration of HOD in liquid-to-supercritical deuterated water". The Journal of Chemical Physics 123 (16): 161105. October 2005. doi:10.1063/1.2110087. PMID 16268674. Bibcode: 2005JChPh.123p1105S.