Young children often ask questions to their parents, which seem ridiculous to adults, so it’s hard for a person to answer them. One such question is: why is the water wet? But if you consider it from a scientific point of view, it will not be so ridiculous.
Wet thing - what does it mean?
Before answering the question of why the water is wet, it is necessary to consider the very concept of “wet”. By this word, a person understands a state of an object in which any liquid is present on its surface. It is important to understand here that this fluid is not necessarily water, although in most cases it is this substance.
The opposite of wet is a dry object, that is, there is no liquid on it.
What is water?
To understand why water is wet, you need to consider what this substance is. It should be noted right away that it can be in three aggregate states: solid (ice), gaseous (water vapor) and liquid (actually water). Only in the latter state can water be wet.
From a chemical point of view, water is formed by H 2 O molecules. They consist of three atoms (2 hydrogen and 1 oxygen). The oxygen atom is much larger than that for hydrogen, its electrons are electrostatically bonded much stronger than a single electron with a single proton in hydrogen. The latter fact leads to the fact that during the formation of the H 2 O molecule, an oxygen atom pulls hydrogen electrons onto itself, that is, it becomes partially negative. Having lost its electron during the formation of a chemical bond, the hydrogen atom acquires a partially positive electric charge. This state of the H 2 O molecule is called polarized. It is this effect that underlies wet water.
Adhesive and cohesive forces
Continuing to consider the question of why water is wet, we now turn to a description of the processes occurring at the molecular level in the water column and on its surface. For this, we introduce two concepts: cohesion and adhesion.
Under the first understand the ability of the molecules of a substance to attract each other. Due to cohesion, liquid water does not spontaneously spill out of the vessel in which it is located. The cohesive forces are due to the electrostatic interaction between the polar H 2 O molecules. In them, partially positive H + atoms of other molecules are attracted to the partially negative atom of O - some molecule.
If we are talking about the thickness of the water, then the resulting force acting on the molecule in question from the side of its neighbors is zero, since they all cancel each other out. If we consider the water surface, then the resulting force will be different from zero. It is directed into the thickness of the liquid and tends to draw molecules from the surface to the depth, as it were. This phenomenon leads to surface tension.
By adhesion is understood the force interaction between the molecules of different substances. Here we are faced with the phenomenon of wettability.
Why is the water wet?
Finally, we come close to the answer to this question. Water is wet because it moistens the surfaces of other bodies. The latter fact is explained by the fact that the adhesive interaction with the surface of the object is stronger than the cohesion between the molecules of this liquid.
Liquid mercury may be mentioned as an example of the opposite. It does not wet almost any solid objects, since the interactions between Hg atoms are significant and exceed any adhesive forces.
Is water wetter or less wet?
Perhaps this question sounds even more unusual than the one that is considered in the article. No matter how strange it may sound, the answer to it is positive: yes, the water can be more or less wet.
As explained above, this property of fluids is associated with a ratio of adhesion and cohesion forces, which, in turn, correlates with surface tension. The stronger the latter, the greater the cohesive forces, and the less wet the water will be. Similar considerations can be made and vice versa.
Does the obtained conclusion take place in practice? Of course it does. A vivid example of "very wet" water is a substance with detergents dissolved in it. They lead to a significant reduction in surface tension for H 2 O, so the water begins to easily "stick" to dirty dishes, which improves its washing properties.
Is the water wet or damp?
The answer to this question involves knowing not only the meanings of words in the Russian language, but also the laws of physics described above in the article.
So, the difference between the words "wet" and "raw" is the level of humidity of the subject in question. If it is too high, so that water is already dripping from it, then they say “sputum”, and vice versa, if there is humidity, but it is not so high that the water drips from a wet object, then the adjective “raw” is used.
Returning to water, we can say the following: when this liquid moistens a solid object, a layer of H 2 O molecules appears on its surface, the local concentration of which is 100% (maximum humidity level). Accordingly, the concentration of H 2 O molecules in the water itself is also 100%. The above arguments make it possible to say that the water is wet rather than wet.
Raw can be called air when water vapor molecules are in it at concentrations below 100%. A towel can also be called raw if it is wiped off with a wet table, and if water does not drip from it.
Other "uncomfortable" questions for children
Why is the water wet and the sky blue? We have already dealt with the first part of the question. As for the color of the sky, to understand it, one should apply knowledge from another branch of physics - optics.
The fact is that the propagation velocity of electromagnetic waves in a medium depends on the frequency of these waves. The larger it is, the stronger the effect of refraction and scattering of rays. It is known that the blue part of the visible spectrum has a shorter wavelength and greater frequency than the red region. This means that when passing through the earth's atmosphere, blue rays will experience greater scattering than red ones. The result of this process is a blue sky during the day and a red sunset in the evening. At night, since there is no need to talk about any sunlight, the sky becomes transparent, and we can observe stars on it.
Why is the water wet and the stones hard? To answer the second part of this question, knowledge of the structure of solids is necessary. In simple terms, the bonding forces between the atoms (molecules) of solid objects are so great that they do not allow them to crumble into small pieces and resist any external force. Therefore, pressing on a stone, we meet its resistance, which we describe using the concept of "hardness".