Heavy water is also known as deuterium oxide and is a chemical element. Hydroxide has a symbol called H and several atoms called 1. When it comes to weight, hydrogen is by far the lightest. Typically, hydrogen is a gas made up of molecules with the formula H2. It doesn’t smell, isn’t toxic, doesn’t look like anything, and is very flammable. Hydrogen is the most common chemical element in the universe. It makes up about 75% of all the usual things we see around us. A lot of hydrogen is found in plasma form on the Sun, which makes it shine. Almost all of the hydrogen on the planet is in the form of molecules like water and organic substances like plants. 

Preparation of Heavy Water

• Multi-stage Electrolysis of Heavy Water

Hydroxide is released faster than deuterium when water is electrolyzed, but not as quickly as deuterium. As a result, H2O bonds break 18 times more often than D2O bonds. Keeping electrolysis going until only a little water is left, the D2O that comes out is pure. When we electrolyzed 30 litres of water, we got about 1ml (about one tablespoon) of heavy water.

• Exchange Reactions

There are also ways to make D2O, a kind of heavy water. It happens, for example, when H2S gas passes through heated water. Deuterium atoms from D2O already in the water are used to replace hydrogen atoms in H2S, so the water stays the same. So, D2S is put into H2S. If you mix H2S with deuterium and cold water, the deuterium from D2S and hydrogen from H2O change places again. The process is repeated, and the cold water gets a little more D2O each time.

• Fractional Distillation

The fractional distillation process could affect how well heavy water separates from normal water, so it might not work. The difference between severe and ordinary water’s boiling points is used in this step. So, the lighter part breaks down first, leaving behind a heavier water-rich residue (D2O).

Properties of Heavy Water

Physical Properties of Heavy Water

Heavy water doesn’t have a colour, smell, or taste like regular water. It’s also effortless to move. It has a lot of different physical properties. Here are some of them:

• Heavy water has a more excellent boiling point, maximum density, and latent heat of vaporisation than water (18 g). Because heavy water has a more immense molecular weight (20 g) than water (18 g), its physical constants are higher.
• Another thing to note is that when heavy water is mixed with water, it has a lower dielectric constant than water.
• Ionic chemicals in heavy water don’t dissolve as well as they do in water, so they don’t mix well.

Chemical Properties of Heavy Water

Heavy water may be employed in any chemical process using water. Heavy water is less reactive than water. Heavy water users may not respond as rapidly as water users. The O–D bond dissociates faster than the O–H bind. The O–D connection is more stable.

• Deuterolysis:  Some inorganic salts can be broken down by the water, but not all of them can be. This is called salt Deuterolysis, and when heavy water is used, it happens in the same way.

AlCl3 + 3D2O → Al(OD)3 + 3DCl

BaS + 2D2O → Ba (OD)2 + D2S

• Action on Metals: Heavy water reacts with metals like sodium and calcium, releasing deuterium and giving heavy alkalis.

2Na + 2D2O → 2NaOD + D2

• Action on Metal oxides: It happens when basic oxides like sodium monoxide and calcium oxide mix with heavy water. This makes heavy alkalis, which are made.

Na2O + D2O → 2NaOD

• Action on non-Metal oxides: Deutero acids are made when heavy water comes into contact with acidic non-metal oxides like sulphur trioxide, dinitrogen pentoxide, and more.
• The action of metal nitrides, phosphides, and carbides: Heavy water breaks down into ammonia with metal nitrides, which is severe.

Mg3N2 + 6D2O → 3Mg(OD)2 + 2ND3

• Formation of salt deuterates: People make salt deuterates with heavy water. They are created when the salt crystallises from a solution in heavy water. CuSO4.5D2O and MgSO4.7D2O are two examples of salts that are salts.
• Exchange Reactions: Heavy water reacts with many different things that have hydrogen atoms, resulting in replacing some or all of the hydrogen atoms with deuterium. The exchange processes occur spontaneously if the compounds have ionic hydrogen atoms.

NaOH + D2O → NaOD + HDO

HCl + D2O → DCl + HDO

• Biological Effects: Heavy water makes plants and animals grow more slowly. Seeds don’t grow in pure and heavy water, and little fish die. In addition, water with a lot of D2O is bad for you.

Uses of Heavy Water

• Heavy water is used to get rid of germs and bacteria.
• People used heavy water’s ability to exchange with other things to find out about the structures and basicity of several oxyacids.
• This is how deuterium is made from heavy water by electrolysis or by reacting with metal-like sodium.
• People who work at nuclear plants use heavy water to slow down energy flow. Uranium atoms need neutrons that move very slowly to break apart, so they must be enormous. The neutrons are slowed down by flowing through heavy water, which acts as a “moderator.”
• A tracer called “heavy water” is used to look into things like the reactions of aromatic electrophilic substitution, metabolic activity, and other things.

Conclusion

D2O, which is heavy water, has fascinated scientists since the discovery of deuterium by Urey in 19311. It’s the density of D2O that makes it a little denser than H2O. This is mainly because deuterium is heavier than hydrogen, but it’s still a big difference. More subtly, deuteration makes hydrogen (or deuterium) bonds stronger in D2O than in H2O3,4 or H2O5, 6. When pure water is deuterated, it changes its pH (or PD) by 0.44. 

This causes a slight rise in the freezing and boiling points by 3.8°C and 1.4°C, respectively. This isn’t true for water that is just dissolving CO2 from the air and making dilute carbonic acid in open containers. This has a much more significant effect on the pH of water, changing it by more than one unit, though.