Semiheavy water is the result of replacing one of the protium in light water to deuterium. It exists whenever there is water with light hydrogen (protium, 1H) and deuterium (D or2H) 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 actually 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.
Famous quotes containing the word water:
“It is moot whether there be divinities
As I finish this play by Webster:
The street-cars are still running however
And the katharsis fades in the warm water of a yawn.”
—Allen Tate (1899–1979)