Heavy water definition
Heavy water is water with the same
chemical formula as regular water (H2O); That is, it also consists of two
hydrogen atoms and one oxygen atom, but it does not contain the ordinary
isotope of hydrogen called Protium, but rather contains one or two of the isotopes
of the hydrogen atom known as Deuterium; This is why heavy water is also known
as deuterium oxide (D2O).[1]
Molecular weight of heavy water
It is indicated that the atomic
weight of deuterium is 2 while the atomic weight of the ordinary hydrogen
isotope protium is 1, and thus the molecular weight of heavy water is
completely different from the molecular weight of ordinary water. Where the molecular
weight of heavy water is 20 if it contains two deuterium atoms; Which is the
sum of twice the atomic weight of deuterium 4 in addition to the atomic weight
of oxygen, which is 16, while the molecular weight of ordinary water is 18;
Which represents the sum of twice the atomic weight of Protium 2 plus the
atomic weight of Oxygen.[2]
The percentage of heavy water in nature
Heavy water is formed naturally,
but in small quantities compared to ordinary water; Where the percentage of its
presence in nature is equivalent to one molecule of it compared to twenty
million molecules of ordinary water, and it is indicated that heavy water does
not have any radioactivity; Because deuterium is considered a stable isotope.[3]
Heavy water use
Heavy water has many uses, most
notably the following:
1. Nuclear reactor applications
The following are the most
important uses of heavy water in nuclear reactors: [4]
1. slowing down the speed of neutrons in nuclear fission
reactors in a process known as neutron quenching; In order to ensure an
effective fission chain reaction, it is one of the two intermediates that can
be used to allow a nuclear reactor to operate using natural uranium,[3] where
it can interact with the isotope of uranium U235 instead of the isotope of
uranium U238.[4]
2. Coolant in nuclear reactors.
3. Nuclear magnetic resonance spectroscopy to detect
magnetic fields around the nuclei of atoms.
4. Infrared spectroscopy instead of regular water.
5. The production of tritium, which is one of the
radioactive isotopes of hydrogen, as it is an active substance in nuclear
fusion reactions, where it is formed by capturing deuterium in heavy water to a
neutron.
2. Biological Studies
Applications
Heavy water is used in the
following biological studies:[4]
1. It is used as a tracer to study the mechanism of some
vital processes; such as respiration and photosynthesis. Interfering with human
and animal metabolic rate testing; By mixing a quantity of heavy water with
water containing heavy oxygen.
2. It is involved in the preparation of many analogues of
organic compounds.
Dangers of drinking heavy water
It is advised to avoid drinking
heavy water because of the damage it causes to the human body as a result of
the interaction of deuterium atoms in the biochemical processes inside the
cells of the body, and it is noteworthy that the damage it causes depends on
the amount that is drunk; Drinking one cup of it or less does not cause any
harm, while drinking a large amount causes a feeling of dizziness because its
density is higher than the density of normal water, which affects the fluid in
the inner ear responsible for maintaining body balance. [5]
Dangers of drinking large amounts of heavy water
Drinking large amounts of heavy
water for continuous periods of time leads to an increase in its percentage in
the water in the body, and the following is an explanation of the extent of its
danger: [5]
· It does not pose a threat to human life as long as its
percentage does not exceed 20% of the water content in the body.
· cause significant damage if it exceeds 20%; It leads
to infertility if it reaches 25%. If it reaches 50% of the water in the body,
it leads to death.
· It should be noted that these effects occur only in
mammalian bodies, while the rest of the living organisms are not affected in
the same way, for example, bacterial growth can increase only above them.
Heavy water uses
Deuterium oxide (D2O), called
heavy water, plays an important role in heavy water nuclear reactors; Where it
can be used in cooling, and controlling the movement of neutrons (in English:
neutron moderator), and the following are many applications for heavy water: [6]
1. Heavy water is used to prepare deuterium.
2. It is used as a tracer to study the mechanism of
cellular respiration and photosynthesis.
3. D2O is used in nuclear magnetic resonance
spectroscopy, which is used to study the magnetic field surrounding the nuclei
of atoms.
4. With deuterium oxide, isotopologues can be prepared
for many organic compounds.
5. Heavy water is used instead of regular water in
infrared (IR) spectroscopy.
6. It is used to slow the movement of neutrons in nuclear
reactors, and this allows the neutrons to react with uranium (235U) instead of
uranium (238U).
7. The metabolic reactions that occur in the human and
animal body can be studied using a solution of deuterium oxide and heavy-oxygen
water; It is a type of heavy water that contains the oxygen isotopes 17O and
18O.
8. Tritium is the active substance used to control
nuclear fusion reactions, and is formed when the deuterium in heavy water
obtains a neutron.
9. Heavy water is used instead of regular water in the
study of proteins using Fourier Transform Infrared Spectroscopy technology
(FTIR: Fourier Transform Infrared Spectroscopy).[7]
Possibility to use heavy water for drinking
Although heavy water is not
considered a radioactive substance, it is not suitable for drinking; This is
because deuterium does not act like the normal hydrogen isotope known as
protium in biochemical reactions, and the body is not affected much if a small
amount of heavy water is drunk. negative effects on the body; As replacing 25%
of the protium leads to sterility, and replacing 50% of it leads to death.[7]
Biological uses of heavy water
Deuterium oxide (D2O) in high
concentrations can reduce high blood pressure caused by salt and ethanol in
mice, in addition to protecting mice from gamma rays, and the use of deuterium
oxide in high concentrations plays an important role in boron neutron trapping
therapy. (in English: boron neutron capture therapy); This allows neutrons to
penetrate into boron compounds that bind in malignant cells.[8]
References
1. Anne Marie Helmenstine (28-1-2020), "Can You Drink
Heavy Water?"، www.thoughtco.com, Retrieved 21-10-2020. Edited.
2. Adam Augustyn (13-11-2019), "Heavy Water"، www.britannica.com,
Retrieved 21-10-2020. Edited.
3. Bethel Afework, Jordan Hanania, Kailyn Stenhouse,
Jason Donev (18-5-2018), "Heavy Water"، energyeducation.ca,
Retrieved 21-10-2020. Edited.
4. "Heavy
Water - Uses, Properties and Reactions",
byjus.com, Retrieved 21-10-2020. Edited.
5. Juan Ramos (14-11-2017), "Heavy
Water: Here’s Why You Shouldn’t Drink Heavy Water"، sciencetrends.com,
Retrieved 21-10-2020. Edited.
6. "What
is Heavy Water?", byjus.com, Retrieved
7-5-2019. Edited.
7. Anne Marie Helmenstine (9-1-2018), "Heavy Water
Facts"، www.thoughtco.com, Retrieved 7-5-2019. Edited.
8. "Pharmacological uses and
perspectives of heavy water and deuterated compounds.",
www.ncbi.nlm.nih.gov, Retrieved 7-5-2019. Edited.
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