Chemistry of water -Part 1-

in StemSocial3 months ago (edited)

The most crucial chemical element is water. Life on the earth's surface wouldn't exist without it. Both the environment in which we live and the makeup of all living things contain it. The nature of our physical and biological world is governed by its physical properties, which are very different from those of other materials. Water is found in living things in amounts ranging from 50 to 90 percent, and it plays a vital role in metabolism wich means it is not an inert substance. A decrease in the amount of water vapor in the atmosphere would increase the impact of ultraviolet solar radiation, intensify the action of those rays, and trigger a number of powerful photochemical reactions that would alter the chemical character of our planet's surface.

  • Nature includes water in all cycles of chemical transformation as it travels the mysterious evolutionary path from the simplest compounds and processes to the self-regulating systems of living matter. Water is the substance that causes ions to dissociate and is involved in chemical reactions like hydrolysis to ensure that molecules are restructured. In oxidation-reduction reactions, water participates also.

Water composition:

Since water is present throughout nature, it is unreasonable to inquire as to who discovered it or when, but from a scientific perspective, we can inquire as to how we came to understand its composition. Water was regarded as one of the four elements by the ancient Greeks, and Henry Cavendish claimed in 1781 that it is produced when hydrogen is burned in the atmosphere. The discovery that water is a mixture of the two elements hydrogen and oxygen was made first by Antoine Lavoisier.
Berzelius and Dulong were the first to carefully examine the composition of water in 1819, and because it was challenging to measure the volumes and densities of gases, they relied on an indirect weighing technique based on the reduction of copper oxide with hydrogen:

CuO + H2 === H2O + Cu

They heated a known weight of copper oxide in a tube, passed hydrogen gas over it, dried it by passing through the first calcium chloride tube, and then collected the water released by passing it into a second, U-shaped tube filled with calcium chloride, which is highly water-absorbing. The weight of the water can be calculated using the weights of the second calcium chloride tube before and after the experiment. As for the weight loss of the copper oxide allows us to calculate the weight of oxygen. And the weight of hydrogen is equal to the difference between the weights of water and oxygen.
The geometry of the water molecule is a tetrahedron with two hydrogen atoms occupying two of its vertices while leaving the other two free. It is an angular molecule with an oxygen atom occupying the vertex and two valence bonds with an angle of 104.5°.

Tetrahedral Structure of Water
The water molecule's structural simplicity is, however, quite relative. In fact, if we consider that both oxygen and hydrogen have isotopes, such as deuterium and tritium for hydrogen and the isotopes of oxygen with the masses 14, 15, 16, 17 and 18, we can see that there are 36 different types of water molecules, 9 of which are composed of stable isotopes. As we can see, only molecules are present in natural water in significant amounts; tritium-containing molecules may also be present, but only in very small quantities.
Unlike the direction in which protons lie, the orbitals of unshared electron pairs are oriented. The oxygen atom's center is surrounded by a tetrahedral arrangement of electric charges; the sign (+) denotes low electron density (the areas where the protons are located), and the sign (-) denotes high electron density (the regions where the orbitals of the unshared pairs are located).

H2O Polarization
Hydrogen bonds hold water molecules together when they are in a liquid state. These bonds maintain a sufficiently ordered distribution of the molecules at temperatures close to absolute zero, allowing one to observe a prefiguration of the crystal lattice where each molecule is bound to four neighbors even in the liquid state. During crystallization, this tetrahedral structure crystallizes into perfect clarity and describes the solid state of water. When the temperature rises, the molecules lose their tetrahedral distribution and arrange themselves in a denser manner. Therefore, liquid water has a shorter intermolecular distance than solid water.
By considering the presence of unshared electron pairs and hydrogen bonds, many characteristics of water's behavior can be understood. We know that water reacts with a wide range of substances, including inert gases (by providing hydrates), so the high chemical activity of water must be attributed to unshared electron pairs.
The emergence of the tetrahedral configuration of water molecules also contributes to the extraordinarily large values of the heats of fusion and vaporization because the dissolution of this configuration requires a significant amount of energy. Water has a fusion heat of 79.7 cal/g and a sublimation heat of 677 cal/g. Water splits into hydrogen and oxygen at high temperatures, and a further increase in temperature causes a dissociation that results in the formation of free hydroxyls.

Bibliographic references:


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To talk about water is to talk about life, literally.
Its structure is what allows it to be the main component and the elementary liquid medium for life.
From the physical and chemical point of view, it is complex and simple at the same time, but it is exciting.
I like the simplicity with which you touch a complex subject.