Water (H2O) is the most abundant substance on our planet, formed by hydrogen and oxygen molecules and commonly in the liquid state.
It is estimated that 71% of the land surface is covered with water, although it is also frozen at the poles and mountain peaks (such as ice and snow) or in the form of gas (vapor) in the atmosphere.
On our planet, water is kept in constant circulation thanks to the water cycle, a cycle of physical state changes (liquid-gas-liquid) that allows the irrigation of the land (rain) and the constant flow of rivers and seas. This cycle is known as the hydrological cycle, and is of vital importance for the atmospheric cooling and climatic stability of the various regions.
Water is the liquid from which life originated and also the universal solvent, that is, it is found to some extent in practically all the compound substances, in almost all the chemical reactions of the planet.
Characteristics Of Water
1. It is insipid
Water does not have a certain flavor (or in any case a neutral taste), so when eaten it will taste, in any case, what is dissolved in it, such as water with sugar or salt.
2. It is transparent
The water does not have a certain color and lets the rays of light pass almost completely, unless there are other substances dissolved in it and that do have a certain color, as occurs in waters rich in organic matter suspended from the mangroves, which is cloudy.
3. It is odorless
Just as he does not like it, water does not smell either, except that which remains of those other substances dissolved in it.
4. Dissolvency
Water is a good solvent for most substances (called hydrophilic) except for fats and lipids that do not dissolve or mix in it (hydrophobic). This is what happens when mixing water with oil: the substances remain separated.
5. Electric conductivity
The common water is a very good conductor of electricity, since electrically charged molecules (ions) are easily associated with it. That’s why most salts are soluble in water. But if all kinds of minerals could be extracted from the water, the resulting liquid (pure water) would be more of an electrical insulator.
6. Magnetism
In a state of purity, water molecules behave diamagnetically, that is, they are repelled by intense magnetic fields.
7. It’s incomprehensible
In almost all conditions, water can not be compressed, a principle used by hydraulic presses. It has a low viscosity (10-3 Pas at about 20 ° C) and subjected to about 200 atmospheres, it is barely possible to compress it by 1%.
8. Sound transmission
The sound propagates in the water practically without loss, especially the low frequencies of it. This property is the one that allows the communication via Sonar, principle copied from the communication of the great marine cetaceans.
9. State changes
Water can be changed with extreme ease of physical condition. Boils at 100 ° C, turning into steam (gas) and freezes below 0 ° C, becoming solid. In any intermediate range, you will find yourself in your predominant liquid state. These water values were used for the construction of the metric scale of temperature.
It should be noted that if there are other substances dissolved in the water, the freezing and evaporation ranges will be altered depending on the substance.
10. Surface tension
Like many other liquids, water has a surface tension, a phenomenon in which water molecules on the surface are attracted to the sides or down by intermolecular forces, offering a minimum surface resistance, as if it were an elastic layer of minimum thickness.
This property is taken advantage of by some insects that walk on the water, or explains why not all the leaves of the trees sink immediately after falling on the surface of a lake.
