Heavy water

Semiheavy water

Deuterium oxide Norsk.jpg

Heavy water (deuterium oxide, D₂O) is a form of water that contains a larger than normal amount of the hydrogen isotope deuterium (D or ²H), rather than the common hydrogen-1 isotope (¹H) that makes up most of the hydrogen in normal water. The presence of deuterium gives heavy water different nuclear properties compared to normal water, which makes it useful in certain types of nuclear reactors and other applications.

Properties

Heavy water is chemically similar to normal water (H₂O), but it has several distinct physical properties. It is about 10.6% denser than normal water, which means that ice made from heavy water will sink in normal water. The boiling point of heavy water is slightly higher than that of normal water, and its freezing point is also higher.

Production

Heavy water is produced through several methods, including the Girdler sulfide process, distillation, and electrolysis. The Girdler sulfide process is the most common method used for large-scale production. This process involves the exchange of hydrogen and deuterium between water and hydrogen sulfide gas.

Applications

Nuclear Reactors

Heavy water is used as a neutron moderator in certain types of nuclear reactors, such as the CANDU reactor (Canada Deuterium Uranium reactor). In these reactors, heavy water slows down neutrons, making it easier for the nuclear fission process to occur with natural uranium.

Scientific Research

Heavy water is also used in various scientific research applications, including neutron scattering experiments and studies of metabolic processes. Because deuterium is a stable isotope, heavy water can be used as a tracer in biological and chemical research.

Medical Applications

In medicine, heavy water is used in some diagnostic techniques and as a contrast agent in certain types of imaging studies. It is also used in metabolic studies to trace the pathways of hydrogen in the body.

Health Effects

While heavy water is not radioactive, it can be harmful if ingested in large quantities. The presence of deuterium can disrupt normal biological processes, leading to potential health issues. However, small amounts of heavy water are generally considered safe.

History

The discovery of heavy water is attributed to Harold Urey, who first identified deuterium in 1931. The first large-scale production of heavy water occurred during World War II, when it was used in the development of nuclear weapons.

See Also

• Deuterium
• Nuclear reactor
• Neutron moderator
• CANDU reactor
• Girdler sulfide process