Heavy Water, D2O

Heavy Water

Heavy water, $D_2O$, has two principal uses: as a moderator in nuclear reactors (slowing fast neutrons without absorbing them the way ordinary water would) and in exchange reactions used to study reaction mechanisms, since the presence of deuterium can be tracked.

It can be made either by exhaustive electrolysis of ordinary water (deuterium, being heavier, is left behind as the lighter protium is preferentially electrolysed away) or obtained as a by-product of certain fertiliser industries. Its physical constants are listed alongside those of ordinary water in Table 9.3.

$D_2O$ also serves as the starting material for making other deuterium-labelled compounds, for example: …