Difference Between Water and Heavy Water

Water is the lifeline of all living organisms. About 70 per cent of the Earths surface is covered with water. Heavy water is also water, but it contains a higher proportion of the hydrogen isotope deuterium.

Two hydrogen atoms and one oxygen atom makes a water molecule. Deuterium is very much the same as that of normal hydrogen, but contains an extra neutron. It is this extra neutron that adds to the weight of the atom, which makes it heavier.

Both heavy water and water are quite different in their physical and chemical properties. While the freezing point of water is zero degrees Celsius, heavy water has a freezing point of 3.82 degrees Celsius. Heavy water has a slightly higher boiling point when compared to water. While the boiling point of water is 100 degrees, it is 101.4 degrees for heavy water.

In density as well, heavy water has a higher density when compared to water. The PH value of heavy water is 7.41 when compared to waters PH value of 7. In terms of dynamic viscosity, heat fusion and heat of vaporization heavy water has higher values than that of water. But water has higher value in surface tension and refractive index.

Another thing that can be seen is that the number of hydrogen bonds per molecule of water is higher in heavy water. This bondage gives heavy water a more tetrahedral shape, and the water a broader structure.

Water is vital for all living organisms, and no organism can live without it.

Heavy water is mainly used in nuclear reactors. Heavy water is used to slow down the neutrons that are released due to fission in the reactors. While water is essential for all, heavy water can be harmful to living organisms.

Summary:

1. Two hydrogen atoms and one oxygen atom makes a water molecule. Heavy water is also water, but it contains a higher proportion of the hydrogen isotope deuterium.

2. Heavy water has a higher freezing and boiling point when compared to water.

3. In terms of density, PH value, dynamic viscosity, heat fusion, heat of vaporization, surface tension and refractive index, heavy water has higher values than that of water.

4. Heavy water has a more tetrahedral shape, and the water has a broader structure.

5. While water is essential for all, heavy water can be harmful to living organisms.

Heavy water is chemically the same as regular (light) water, but with the two hydrogen atoms (as in H2O) replaced with deuterium atoms (hence the symbol D2O). Deuterium is an isotope of hydrogen. it has one extra neutron.Top of Form

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Is "heavy water" dangerous?

What is the deal with heavy water? Is it harmful to humans, and if so, in what way? I've read a little bit about it and its use in nuclear reactors, but the politics of that aspect of it make it hard to find out simple facts about the substance itself.

Heavy water (D2O) is one of several commonly-used moderators found in nuclear reactors (others include graphite, beryllium and light--i.e., ordinary--water). A moderator slows down fast-moving neutrons released by nuclear fission so they have more time to react with the nuclear fuel. That permits a sustained, controlled chain reaction using unenriched uranium. Reactors using enriched uranium don't require a moderator.

Heavy water is chemically identical to the ordinary water we know and love. The difference is that heavy water is made with a hydrogen isotope that has a neutron in addition to the proton in its nucleus. This isotope is called deuterium and occurs naturally at the rate of about 1 deuterium atom for every 6,700 normal hydrogen or protium atoms, which have just one proton and no neutrons in the nucleus. Deuterium is not radioactive, unlike the even heavier and rarer hydrogen isotope tritium, which is made primarily in nuclear reactors and has two neutrons in the nucleus. Tritium, which has a half-life of about 12.5 years, finds use in luminescent paints for watches and various displays, chemical tracers, and hydrogen bombs. If you're organizing the chemicals in your closet, don't get the deuterium and the tritium mixed up.

There are physical differences between light and heavy water. Heavy water is (duh) heavier, having a density of 1.108 g/cm3. Heavy water ice will actually sink in light liquid water. The freezing and boiling points are also elevated somewhat, with heavy water freezing at 3.81C (38.86F) and boiling at 101.42C (214.56F) at standard atmospheric pressure.

Despite the fact the light water and heavy water are chemically identical, heavy water is mildly toxic. How can this be? Since heavy water is heavier than normal water, the speed of chemical reactions involving it is altered somewhat, as is the strength of some types of bonds it forms. This affects certain cellular processes, notably mitosis, or cell division, due to the difference in binding energy in the hydrogen bonds needed to make certain proteins. Mouse studies have shown that drinking only heavy water along with normal feed eventually causes degeneration of tissues that need to replenish themselves frequently, and leads to cumulative damage from injuries that don't heal as quickly. One study likens the effects to those suffered by chemotherapy patients. Heavy water toxicity manifests itself when about 50% of the water in the body has been replaced by D2O. Prolonged heavy water consumption can cause death.

Don't get any funny ideas about using heavy water as a virtually untraceable and undetectable murder weapon, though. Given its role in breeder reactors for producing weapons-grade plutonium, production and distribution of heavy water is closely monitored and controlled. Obtaining a significant amount is damn near impossible for the average Joe, and you'd need a LOT of it to kill anyone. It's also expensive--one estimate puts the price at about $300 per kilogram. Hit 'em over the head with a bottle of Poland Spring and save yourself some grief.

Heavy Water Production

Heavy water is the key to one type of reactor in which plutonium can be bred from natural uranium. As such, the production of heavy water has always been monitored, and the material is export controlled. In addition, a source of deuterium is essential for the production of tritium and 6LiD, two ingredients of thermonuclear weapons. A nation seeking large quantities of heavy water probably wishes to use the material to moderate a reactor, and may be planning to produce plutonium. However, CANDU (CANadian Deuterium Uranium) reactors designed and built in Canada are used for commercial electric power production.

Heavy water, D2O, is water in which both hydrogen atoms have been replaced with deuterium, the isotope of hydrogen containing one proton and one neutron. It is present naturally in water, but in only small amounts, less than 1 part in 5,000. Heavy water is one of the two principal moderators which allow a nuclear reactor to operate with natural uranium as its fuel. The other moderator is reactor-grade graphite (graphite containing less than 5 ppm boron and with a density exceeding 1.50 gm/cm 3 ). The first nuclear reactor built in 1942 used graphite as the moderator; German efforts during World War II concentrated on using heavy water to moderate a reactor using natural uranium.

The importance of heavy water to a nuclear proliferator is that it provides one more route to produce plutonium for use in weapons, entirely bypassing uranium enrichment and all of the related technological infrastructure. In addition, heavy-water-moderated reactors can be used to make tritium.

Although one speaks of "making" heavy water, deuterium is not made in the process; rather, molecules of heavy water are separated from the vast quantity of water consisting of H2O or HDO (singly deuterated water), and the "dross" is discarded. Alternatively, the water may be electrolyzed to make oxygen and hydrogen containing normal gas and deuterium. The hydrogen can then be liquefied and distilled to separate the two species. Finally, the resulting deuterium is reacted with oxygen to form heavy water. No nuclear transformations occur.

The production of heavy water in significant amounts requires a technical infrastructure, but one which has similarities to ammonia production, alcohol distillation, and other common industrial processes. One may separate heavy water directly from natural water or first "enrich" the deuterium content in hydrogen gas. It is possible to take advantage of the different boiling points of heavy water (101.4 C) and normal water (100 C) or the difference in boiling points between deuterium (-249.7 C) and hydrogen (-252.5 C). However, because of the low abundance of deuterium, an enormous amount of water would have to be boiled to obtain useful amounts of deuterium. Because of the high heat of vaporization of water, this process would use enormous quantities of fuel or electricity. Practical facilities which exploit chemical differences use processes requiring much smaller amounts of energy. Separation methods include distillation of liquid hydrogen and various chemical exchange processes which exploit the differing affinities of deuterium and hydrogen for various compounds. These include the ammonia/hydrogen system, which uses potassium amide as the catalyst, and the hydrogen sulfide/water system (Girdler Sulfide process).

Separation factors per stage are significantly larger for deuterium enrichment than for uranium enrichment because of the larger relative mass difference. However, this is compensated for because the total enrichment needed is much greater. While 235U is 0.72 percent of natural uranium, and must be enriched to 90 percent of the product, deuterium is only .015 percent of the hydrogen in water and must be enriched to greater than 99 percent. If the input stream has at least 5 percent heavy water, vacuum distillation is a preferred way to separate heavy from normal water.

This process is virtually identical to that used to distill brandy from wine. The principal visible difference is the use of a phosphor-bronze packing that has been chemically treated to improve wettability for the distillation column rather than a copper packing. Most organic liquids are non-polar and wet virtually any metal, while water, being a highly polar molecule with a high surface tension, wets very few metals. The process works best at low temperatures where water flows are small, so wetting the packing in the column is of particular importance. Phosphor-bronze is an alloy of copper with .02-.05 percent lead, .05-.15 percent iron, .5-.11 percent tin, and .01-.35 percent phosphorus.

Heavy water is produced in Argentina, Canada, India, and Norway. Presumably, all five declared nuclear weapons states can produce the material. The first commer-cial heavy water plant was the Norsk Hydro facility in Norway (built 1934, capacity 12 metric metric tons per year); this is the plant which was attacked by the Allies to deny heavy water to Germany. As stated above, the largest plant, is the Bruce Plant in Canada (1979; 700 metric tons/year). India's apparent capacity is very high, but its program has been troubled. Accidents and shutdowns have led to effective limitations on production.

The Bruce Heavy Water Plant in Ontario, Canada, is the world's largest producer of D2O. It uses the Girdler Sulfide (GS) process which incorporates a double cascade in each step. In the upper ("cold," 30-40 C) section, deuterium from hydrogen sulfide preferentially migrates into water. In the lower ("hot," 120-140 C) section, deuterium preferentially migrates from water into hydrogen sulfide. An appropriate cas-cade arrangement actually accomplishes enrichment. In the first stage the gas is enriched from 0.015% deuterium to 0.07%. The second column enriches this to 0.35% , and the third column achieves an enrichment between 10% and 30% deuterium. This product is sent to a distillation unit for finishing to 99.75% "reactor-grade" heavy water. Only about one-fifth of the deuterium in the plant feed water becomes heavy water product. The production of a single pound of heavy water requires 340,000 pounds of feed water.

Difference Between Distilled Water & Drinking Water: Drinking water considered fit for human consumption comes from many sources, all of which must comply with the safety standards outlined by the U.S. Environmental Protection Agency. Distilled water is the purest form of water because it typically has the lowest levels contaminants and minerals. Although distilled water is commonly used for household needs such as ironing or steam cleaning, other types are more often consumed as drinking water.

Distilled Water: Distilled water is made by boiling water -- usually from municipal sources -- and collecting the steam as it condenses. Minerals and most contaminants and chemicals are left behind, at least those which have a higher boiling point than water. Distillation is most effective in removing heavy metals, nitrates and minerals, and the boiling process kills the vast majority of microorganisms such as bacteria, fungi and viruses. Some chemicals that have a lower boiling point than water, such as chlorine and benzene, are vaporized and remain in the distilled water unless they are filtered out with charcoal. Distilled water tastes flat because of the lack of minerals and it tends to leach plastic if its stored in plastic containers for long periods of time. The health consequences of drinking distilled water on a regular basis are unclear. Some doctors and researchers believe it might pull minerals and electrolytes out of your body.

Spring Water: Spring water comes from naturally occurring springs, which are underground sources that are usually uncontaminated. Spring water typically undergoes some processing and filtering to remove debris and kill bacteria and other microbes, but most of the mineral content -- such as calcium and magnesium -- is left in the water. Consequently, spring water tastes fresher or crisper than distilled water to most people. Spring water also leaves a different feel in your mouth compared to distilled water. Spring water may also contain trace amounts of electrolytes such as sodium and potassium.

Purified Water: Purified water is a general term that usually means the water is filtered in some way. Water filtration can be accomplished via reverse osmosis or activated carbon and ceramic filters, although the common goal is to remove harmful substances from the water. Municipal water from your tap should be safe according to government guidelines, so the EPA only recommends additional water filtration at home in order to improve the taste of your drinking water. However, the EPA admits that municipal drinking water can be expected to contain some contaminants, so people with severely weakened immune systems or serious health conditions may benefit from further purifying their water or buying bottled water. In terms of taste and mineral content, water purified by reverse osmosis is the most similar to distilled water.

Bottled Water: Bottled water includes virtually every type of drinking water including tap water, spring water, filtered water and even ozonated water -- which is infused with oxygen. Some brands have been heavily criticized because they use unfiltered municipal water. On the other hand, some brands are highly filtered and purified, and some contain additional minerals and electrolytes. Some bottled waters contain added fluoride, according to the Centers for Disease Control and Prevention, so read labels carefully or contact the company and ask if you are concerned about fluoride consumption.