Some Important Reactions of Heavy Water

Heavy water is a form of water in which deuterium is incorporated instead of protium. Hydrogen has three isotopes mainly- protium, deuterium, and tritium. Therefore, heavy water differs from some normal water in properties. 

These changes in properties are due to the change in the number of ions. For example, deuterium naturally found in water is separated by multiple stages of electrolysis. Then the separated deuterium reacted with oxygen to form heavy water.

Heavy water importance

Heavy water is a type of water that contains deuterium instead of protium (a single H atom). Deuterium is a hydrogen isotope with two neutrons. D2O is the symbol for it. Due to the heavier deuterium, this will have different nuclear characteristics than a regular H atom. The human body contains a small quantity of heavy water by nature. A considerable volume of heavy water might make a healthy human body sick. Multiple steps of electrolysis separate the deuterium found naturally in water. The deuterium was then extracted and interacted with oxygen to form heavy water. The girdler sulphide method also creates heavy water. The boiling temperature, freezing point, and heavy water density are somewhat greater than ordinary water.

Reactions of heavy water

Heavy water has physical properties as compared to ordinary water. But the chemical properties of heavy water occur at a slower rate when compared to normal water.

• When heavy water is electrolysed, deuterium is obtained. (D2O → D2+O2)
• Heavy water reacts with alkali at a slow pace forming deuterium

D2​O+2Na → 2NaOD+D2​

• Oxides of metals react with heavy water and form deuteroxides.

Na2​O+D2​O → 2NaOD

• Heavy water reacts with non-metallic oxides to form deuteron acids.  

D2​O+N2​O5 ​→ 2DNO3​

• Formation of deuterates
• Formation of Deutero-ammonia
• Formation of Deutero-benzene
• Formation of Deutero methane

Types of heavy water 

Heavy water has 3 different types, and each one of them has different reactions in different situations.

Semi-heavy water

• Semi-heavy water is somewhat between ordinary water and hard water
• Denoted as HDO
• It has both protium and deuterium as  hydrogen components (50-50)
• It is more abundant in heavy water than pure D2O and H2O.
• Several studies carried out testing semi-heavy water as a moderator in reactors. But it will cause neutrons to travel a longer distance and reduce thermal neutron flux. So using semi-heavy water as a moderator might not be a good idea.

Heavy oxygen water

• It contains heavy isotopes of oxygen
• It is used in Positron-Emission Tomography (PET)
• Used in DNA stable isotope probing
• Used in secondary ion mass spectrometry
• Used in plant ecology

Tritiated water

• It is a form of water with tritium as a hydrogen component.
• It is radioactive
• Hazardous when inhaled, ingested, and absorbed through the skin
• When it is used with phosphorus, it glows in the dark. This is used in signboards.
• Found in nuclear weapon
• Used as a radioactive tracer
• Detected by liquid scintillation counting

Conclusion

Heavy water is a form of water with a deuterium composition. The number of neutrons in hydrogen, deuterium, and tritium is 1, 2, and 3. This change in the number of neutrons will produce some changes in the properties of that element like boiling point, melting point, etc. Heavy water has physical properties as compared to ordinary water. But chemical properties of heavy water take place at a slower rate when compared to normal water. When heavy water is electrolysed, deuterium is obtained. Heavy water reacts with alkali at a slow pace forming deuterium; oxides of metals react with heavy water and form deuteroxides. 

Heavy water reacts with non-metallic oxides to form deuteron acids. Formation of deuterated, Formation of Deutero-ammonia, Formation of Deutero-benzene, and Formation of Deutero methane are some of the important chemical reactions associated with hard water.