The key difference between heavy water and light water is that heavy water has deuterium isotope whereas light water has protium isotope.
Water is dihydrogen monoxide (H2O). It is a very common liquid because we all need to drink water for the proper functioning of our body. Water is truly a wonder molecule. It is the most abundant inorganic compound in living matter. More than 75% of our body is composed of this inorganic compound. It is a component of cells, and act as a solvent and reactant. In this article, we will discuss two types of water: heavy and light water. The difference between heavy water and light water is in their chemical composition as these forms of water have isotopes of hydrogen rather than hydrogen atoms.
CONTENTS
1. Overview and Key Difference
2. What is Heavy Water
3. What is Light Water
4. Side by Side Comparison – Heavy Water vs Light Water in Tabular Form
5. Summary
What is Heavy Water?
Heavy water has its two hydrogen atoms of H2O replaced by deuterium atoms. That means; it has two deuterium atoms rather than hydrogen atoms. It is analogous to water. Deuterium is one of the isotopes of hydrogen. The nucleus of deuterium has a proton and a neutron. Therefore, the mass number of it is two, and the atomic number is one. Also, deuterium is given as 2H and is known as heavy hydrogen. But, most commonly it is represented with D. Therefore, heavy water has the molecular formula of D2O.
Figure 01: Heavy Water for Nuclear Reactors
Heavy water is transparent and has a pale blue color. It can exhibit different chemical and physical properties than its hydrogen analog. The molar mass of heavy water is 20.0276 g mol−1. Moreover, this form of water is useful in nuclear reactors and studies of chemical and biochemical processes (used as an isotropic tracer).
What is Light Water?
Light water refers to the water, H2O, which is known to all. Water is something without which we cannot live. Two hydrogens covalently bind to an oxygen atom to form water molecules. The molecule gets a bent shape to minimize the electron lone pair-bond repulsion, and the H-O-H angle is 104o.
Figure 02: Light Water is Normal Drinking Water
Water is a clear, colorless, tasteless, odorless liquid, and it occurs in various forms such as mist, dew, snow, ice, vapor, etc. But, it goes to the gas phase when we heat it above 100°C at the normal atmospheric pressure. At room temperature, it is a liquid although it has a low molecular weight of 18 gmol-1.
The ability of water to form hydrogen bonds is one of its most unique characteristics. A single water molecule can form four hydrogen bonds. Furthermore, oxygen is more electronegative than hydrogen, thus making the O-H bonds in water molecule polar. Because of its polarity and the ability to form hydrogen bonds, water is a powerful solvent. It is known as a universal solvent due to its capability to dissolve a large number of materials.
Moreover, water has a high surface tension, and high adhesive, cohesive forces. Thus, it can withstand temperature changes without going to the gas or solid form. And, this is known as having a high heat capacity, which is important for the survival of living organisms.
What is the Difference Between Heavy Water and Light Water?
Heavy water is a form of water which has its two hydrogen atoms of H2O replaced by deuterium atoms. Soft water is ordinary water which has two hydrogen atoms and an oxygen atom in its molecule. So, the key difference between heavy water and light water is that heavy water has deuterium isotopes whereas light water has protium isotopes.
Moreover, the molar masses of heavy and light water are also different from each other. The molar mass of heavy water is 20.0276 g/mol and the molar mass of light water is 18 g/mol. Also, a further difference between heavy water and light water is their chemical formulas; for heavy water, it is D2O while for light water it is H2O.
Summary – Heavy Water vs Light Water
Water is essential for all of us and we need to drink a sufficient amount of water daily. There are two forms of water as heavy water and light water. The key difference between heavy water and light water is that heavy water has deuterium isotope whereas light water has protium isotope.
Reference:
1. “Light Water.” Light Water – Energy Education, Available here.
2. Britannica, The Editors of Encyclopaedia. “Heavy Water.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 2 Mar. 2016, Available here.
Image Courtesy:
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