WHAT IS IRREGULAR WATER DILATION? - SCIENCE - 2025

The irregular expansion of water is a physical property that causes the water undergoes an expansion as it freezes. It is considered to be an irregular property, because most elements expand in heat and contract in cold. However, in water the expansion process occurs at either of the two temperature changes.

Water is usually considered the most common liquid because of its abundance on Earth. But in reality it is the opposite: its anomalous properties make it the most unusual liquid.

Image source: Wikimedia.org.

However, it is precisely its irregular properties that have allowed the development of life on Earth.

Thermal expansion and density of bodies

Thermal expansion or dilation is a phenomenon that occurs when the size of an object increases due to a change in its temperature.

When the temperature of a body increases, this causes its molecules to move faster. This movement creates a greater space between these molecules and this new space causes the size of the object to increase.

It is important to note that not all bodies expand the same. For example, metals such as aluminum and steel are elements that when heated achieve greater expansion than glass.

When a body undergoes thermal expansion, not only its size changes 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 an element has in a given space.

For example, steel has a higher density than feathers. That is 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 dilation of water

Thermal expansion in water has special characteristics that are essential for the preservation of life.

On the one hand, when water is heated it undergoes the same expansion process as most bodies. Its molecules separate and expand, transforming into water vapor.

However, when it cools, a unique 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 molecules of frozen water clump together in different structures than other materials, which leave large spaces between them. Therefore they occupy a greater volume than water in liquid state.

An everyday example in which this phenomenon can be observed is the preparation of ice in ice buckets. When the ice buckets are filled with water in a liquid state, it is impossible to fill them above the rim because obviously it would spill.

However, when removing the ice it is possible to observe how it protrudes from the ice buckets. Thus demonstrating that its volume has increased during the freezing process.

Obviously, when the molecules of water turned into ice expand, their density also decreases. Therefore frozen water is less dense than liquid water, which gives ice the property of floating.

This can be seen in very simple examples such as when the ice that has been added to a drink floats in the glass.

But it can also be observed in large natural phenomena such as the ice sheet that forms on water in winter and even in the existence of icebergs.

The importance of irregular water expansion

The irregular dilation of the 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 water.

In aquatic life

In bodies of water such as lakes, it is possible to observe that when winter comes the upper layer of the water freezes. However, the water below remains in a liquid state.

If ice were denser than water, this frozen layer would sink. This would expose a new liquid layer to the cold of the atmosphere and freeze to sink. In this way, all the water in the lakes would freeze, endangering underwater life.

However, thanks to the irregular properties of water, a different phenomenon occurs. When the surface layer freezes, the water below it is kept at a temperature of 4 ° C.

This occurs thanks to the fact that the water reaches its highest density at 4 ° C, that is, the bottom water will always be at its maximum at this temperature.

If it did eventually increase, the density would push it to 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 in the water.

Those 4 degrees are what make the difference for all the creatures that live in the waters of the poles, such as orcas and crabeater seals.

In life out of the 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 make up 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, the irregular dilation of the water also affects ocean currents. Therefore, it also has effects on the climatic conditions of the planet.

References

1. Chaplin, M. (SF). Explanation of the Density Anomalies of Water. Recovered from: lsbu.ac.uk
2. Helmenstine, A. (2017). Why Does Ice Float? Recovered from: thoughtco.com
3. Kids & Science. (SF). The Anomaly of Water. Recovered from: vias.org
4. Meier, M. (2016). Ice. Recovered from: britannica.com
5. Study.com. (SF). Thermal Expansion: Definition, Equation & Examples. Recovered from: study.com.