The Irregular water dilatation Is a physical property that causes the water to undergo an expansion process when it freezes.
It is considered to be an irregular property, because most elements expand with heat and contract with cold. However, in the water the expansion process occurs in either of the two temperature changes.
Source image: Wikimedia.org.
Usually, water is considered the most common liquid because of its abundance on Earth. But in fact it is quite the opposite: its anomalous properties make it the most atypical liquid.
However, it is precisely its irregular properties that have allowed the development of life on Earth.
The thermal expansion and the density of the bodies
The thermal expansion or expansion is a phenomenon that occurs when the size of an object increases because of a change in the temperature of the object.
When the temperature of a body increases, this causes its molecules to move with greater speed. This movement causes that there is a greater space between these molecules and this new space causes that it increases the size of the object.
It is important to note that not all bodies expand equally. For example, metals such as aluminum and steel are heating elements that reach greater expansion than glass.
When a body undergoes thermal expansion, it not only changes its size but also its density.
Density is the amount of matter contained in a unit of volume. This, in other words, is the total number of molecules that have an element in a given space.
For example, steel has a higher density than feathers. That's why a kilo of steel takes up less space than a kilo of feathers.
When a body expands, it retains the same mass but increases the space it occupies. Therefore, when the temperature increases, the size also increases but the density decreases.
Irregular water dilation
The thermal expansion in the water presents special characteristics that are fundamental for the preservation of life.
On the other hand, when the water heats up, it undergoes the same process of expansion as most bodies. Its molecules separate and expand into water vapor.
However, when cooled a single process occurs: as its temperature drops, this liquid begins to compress.
But when it reaches 4 ° C, it expands. Finally, when it reaches 0 ° C, the temperature necessary for its freezing, its volume increases up to 9%.
This is because the frozen water molecules are grouped in structures different from those of other materials, which leave large spaces between them. Therefore they occupy a greater volume than the water in liquid state.
A daily example in which this phenomenon can be observed is the preparation of ice in ice cubes. When the ice cubes are filled with liquid water, it is impossible to fill them above the edge because it would obviously be spilled.
However, when removing the ice it is possible to observe how it protrudes from the ice cubes. Proving that the volume of this has increased during the freezing process.
Obviously, when the water molecules converted to ice expand, their density also decreases. Therefore, frozen water is less dense than liquid water, which gives the ice the property of floating.
This can be observed in very simple examples as when the ice that has been put into a drink floats in the glass.
But it can also be observed in great natural phenomena like the layer of ice that is formed on the water in winter and even in the existence of the icebergs.
The importance of irregular water expansion
The irregular dilation of water is not only a scientific curiosity. It is also a phenomenon that has played a fundamental role in the development of life on Earth, both inside and outside the water.
In aquatic life
In bodies of water like lakes, it is possible to observe that when winter arrives the upper layer of water freezes. However, the water below is kept in the liquid state.
If the ice were denser than the water, this freezing layer would sink. This would cause a new liquid layer to be exposed to the cold of the atmosphere and to freeze until sinking. In this way, all the water in the lakes would freeze, endangering the underwater life.
However, due to the irregular properties of water a different phenomenon occurs. When the surface layer freezes, the water below it is preserved at a temperature of 4 ° C.
This happens because the water reaches its highest density at 4 ° C, ie the bottom water will always be maximum at this temperature.
If it eventually increased, the density would push it toward the surface where the ice sheet would freeze it again.
Thanks to this phenomenon, the temperature of the bodies of water remains stable and protected from the cold of the atmosphere. This guarantees the survival of the animal and plant species that live inside the water.
Those 4 degrees are the ones that make the difference for all creatures that live in the waters of the poles like killer whales and killer whales.
In life outside water
Human life and in general all forms of life that exist on Earth, also benefit from the anomalous qualities of water.
On the one hand, it is necessary to consider that most of the oxygen comes from the different species that compose the phytoplankton. This form of life would not survive if the oceans could freeze and this would hinder the development of human and animal life.
On the other hand, irregular water expansion also affects ocean currents. Therefore, it also has effects on the climatic conditions of the planet.
References
- Chaplin, M. (S.F.). Explanation of the Density Anomalies of Water. Retrieved from: lsbu.ac.uk
- Helmenstine, A. (2017). Why Does Ice Float? Retrieved from: thoughtco.com
- Kids & Science. (S.F.). The Anomaly of Water. Retrieved from: vias.org
- Meier, M. (2016). Ice. Recovered from: britannica.com
- Study.com. (S.F.). Thermal Expansion: Definition, Equation & Examples. Retrieved from: study.com.