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:
“I respect the ways of old folks, but the blood of a rooster or a goat cannot turn the seasons, change the course of the clouds and fill them up with water like bladders. The other night, at the ceremony for Legba, I danced and sang my fill: I am a black man, no? and I enjoyed it like a true Negro should. When the drums beat, I feel it in the pit of my stomach, I feel the itch in my hips and up and down my legs, I have got to join the party. But that is all.”
—Jacques Roumain (1907–1945)