We know from the school course that water is a substance that is present almost everywhere, as well as about its dominant role in the formation and maintenance of most life forms. What else can be said about the amazing properties of H 2 O?
Physics says that one of the main properties is the density of water. We will consider this criterion in more detail. What is this parameter? The density of water, like any other substance or material, reflects how much, or rather, what mass is contained in a certain volume of substance.
Why is water so amazing that it is necessary to speak about its density separately? Firstly, it is justified by the number of its species. Water can be fresh and salty, heavy and superheavy, living and dead. In addition, everyone is familiar with such definitions as groundwater and mineral water, rainwater or meltwater , structured and even dry. At the same time, water, as we all remember, can be in a solid, gaseous or liquid state, called aggregate. Naturally, the density of salty water will differ from the density of rain or frozen.
The characteristics of substances (including the density of water) are studied under normal conditions, which assume an atmospheric pressure of 760 mm Hg. Art. and ambient temperature equal to 0 0 . When these indicators change, the characteristics of substances change to a certain extent. All but water. The density of water at various temperatures under normal conditions will not be indicative.
Unlike other elements that reduce the density index when heated, water in the range from 0 to 4 degrees Celsius increases its density. During cooling, the volume and density of water again behave uncharacteristically: its volume increases and its density decreases. This is exactly what can be observed in a situation where frozen water breaks water pipes. In wildlife, an unusual feature of H
2 O protects the lower layers of water bodies from freezing and saves the lives of their inhabitants. As for the increase in water temperature, after a limit of 4
0 C, its density, as with cooling, begins to fall. Sea water also breaks these views, showing maximum density at sub-zero temperatures.
It is an amazing fact that perfectly clean water, without air bubbles present and microscopic inclusions of dirt or dust, can be cooled to –70 degrees, without ice formation or heated without boiling to a temperature limit of 150 degrees Celsius. Such anomalies are possible under a number of conditions (increased pressure, for example), and their reproduction is possible only in laboratory conditions.
In general, the density of water is affected by the presence of impurities, gas bubbles and salts in its composition, atmospheric pressure, ambient temperature, and a number of other external factors. This simple substance does not cease to amaze scientists with its absolutely fantastic physical properties, the ability to change the structure and chemical composition.