11 PHYSICAL AND CHEMICAL PROPERTIES OF WATER - BIOLOGY - 2024

The physical and chemical properties of water make it the most important compound on the planet, which integrates natural ecosystems and is essential for the maintenance and reproduction of life on the planet.

Water, a vital resource for the existence of life on the planet, is odorless, insipid and colorless, 97.2% being found in the seas, lakes, rivers and oceans, and the remaining 2.8% in the form of fresh water.

From the 640 century BC the Greek philosopher Thales of Miletus affirmed that water is everything, considering it as the basic element of the universe.

In the 18th century they refuted Thales of Miletus, when the English chemist Cavendish, who synthesized water from a combustion of air and hydrogen, and Lavoisier, proposed that water is not an element, but a chemical compound.

Main physicochemical properties of water

Physical properties

1- It can be found in the three states of matter

Water is a chemical compound that can be found in solid, liquid and gaseous forms.

In its solid phase, the particles are closely linked to each other, hence, for example, an ice cube can maintain its shape for a time regardless of where it is submerged.

In its solid state, water is usually found in the form of ice in snowflakes, glaciers and polar caps.

In its liquid phase, the molecules separate, allowing the water to take the shape of the container that contains it.

It can be found in nature as rain, drops of water, in the form of dew on vegetation and in oceans, rivers, lakes and seas.

And, in its gaseous phase, the molecules are completely separated and disordered, which causes the water to become gas or water vapor and can find it in the form of mist and vapor as is the case with clouds.

It is thanks to this property that the processes of evaporation, condensation, sublimation, freezing, fusion and volatilization exist.

These are the processes through which water leaves its liquid state to become water vapor and freeze until it falls in the form of rain or hail, which can leave frost or ice and even then melt with heat.

You may be interested The States of Water: Solid, Liquid and Gaseous.

2- It has stable temperature markers

Water reaches its freezing point at zero degrees Celsius and its boiling point at one hundred degrees.

Hence, as long as the water has a temperature greater than zero degrees and less than one hundred, it will always be in a liquid state.

3- It has a high specific heat index

This index refers to the amount of heat that a substance can absorb. In the case of water, it has a specific heat that is higher than that of any other substance, hence it can absorb large amounts of heat and its temperature drops more slowly than that of other liquids since it releases energy as it cools.

4- The surface tension is high

Understanding by this the amount of energy that is required to increase the surface of a liquid per unit area.

In the case of water, the molecules that make it up are united and have a great cohesion force, hence its spherical geometry achieves the maximum volume in a minimum area.

Surface tension is the physical effect that forms a kind of hard elastic membrane on the surface layer of water that is at rest.

This allows, for example, that the insects land on the water droplets without sinking or that the water droplets can remain at rest while conserving their volume in a small space.

Chemical properties

5- Composition

Water is made up of one oxygen atom and two hydrogen atoms, a simple molecule that has polar bonds that allow hydrogen bonds to be established between adjacent molecules.

This bond is of great importance since it gives water properties that allow it to have a greater mass, and to reach high melting and boiling points, which are essential for water to be in a liquid state on earth.

6- Universal solvent

Thanks to this it can dissolve more substances than any other liquid. Its molecules are polar, hence they have zones of positive and negative charges.

Likewise, its molecules are dipolar, that is, the central oxygen atom shares a pair of electrons with each of the two hydrogen atoms, which makes it a great solvent medium for ionic compounds such as minerals and carbohydrates.

This property of water is due to its ability to form hydrogen bonds with other substances, which dissolve when they interact with the polar molecules of water.

7- Its molecules have a high cohesion force

Its molecules, by attracting each other, remain linked to each other. By having hydrogen molecules, they are in charge of being strongly united, forming a compact structure that turns water into an incomprehensible liquid thanks to its high adhesion force.

8- Its density is 1kg / l

This density increases as the temperature decreases, reaching a maximum density of 4 degrees.

It is due to this property that ice can float on water, which is why when a lake or sea freezes the ice layer floats on the surface isolating the rest of the water mass, preventing it from melting.

9- Low degree of ionization,

This is because only one in every 551,000,000 water molecules is dissociated in ionic form. For this reason, the PH of the water is considered neutral.

10- Form complex combinations

It is capable of forming complex combinations by joining some salts, giving rise to hydrates, substances that contain water.

Likewise, water reacts with many metallic and non-metallic oxides in order to form hydroxides and oxacids.

11- Generates the hydrophobic effect

It is a phenomenon that is appreciated when nonpolar substances come into contact with water.

Hydrophobic molecules tend to aggregate and join, excluding water molecules, a clear example of this property being the fact that when water and oil are joined, the mixture is separated into an aqueous and an oily phase.

References

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