One of the basic things that we learn in a science class at school is that water can exist in three different States: solid ice, liquid water or gaseous steam. But recently, an international team of scientists have discovered indications that liquid water can actually exist in two different States.
Conducting research — the results were then published in the International Journal of Nanotechnology — scientists suddenly discovered that the water temperature from 50 to 60℃ modify some of the properties. This feature is the possible existence of a second liquid water has ignited a hot debate in scientific circles. If this is confirmed, the discovery will be used in a variety of areas, including nanotechnology and biology.
The state of aggregation, which is also called “phases”, is a key concept in teaching about systems of atoms and molecules. Roughly speaking, the system consisting of many molecules can be organized in a number of configurations depending on its total energy. At high temperatures (and hence higher energy levels) molecules available more configurations, that is, they are less rigidly organized and move relatively freely (gas phase). At lower temperatures molecules have available fewer configurations and they are more organized phase (liquid). If the temperature drops even lower, they will take one specific configuration and form a rigid body.
This overall situation for relatively simple molecules such as carbon dioxide or methane, which have three clearly distinguishable States (liquid, solid and gas). But more complex molecules have a greater number of possible configurations, and therefore the number of phases increases. A perfect illustration of this dual behavior of liquid crystals which are formed from the complexes of organic molecules and can flow like a liquid while preserving a solid crystalline structure.
As phases of a substance are determined by its molecular configuration, a physical properties dramatically change when a substance goes from one state to another. In the aforementioned study, the researchers measured several control properties of water with temperature 0 to 100 ℃ at normal atmospheric conditions (water is liquid). Suddenly they found dramatic variations in such properties as, for example, the surface tension of water and refractive index (an indicator of how light passes through water) at a temperature of about 50℃.
The special structure of the
How is that possible? The structure of the water molecule, H₂O, very interesting and can be depicted as a kind of arrow where the oxygen atom is located at the top, and two hydrogen atoms “escorted” him from the flanks. Electrons in molecules tend to be distributed asymmetric way, resulting from the oxygen molecule gets a negative charge compared to the hydrogen side. This simple structural feature leads to the fact that water molecules begin in a certain way to interact with each other, their opposite charges attract, forming so-called hydrogen bond.
This allows the water in many cases to behave differently than they do, according to the observations of other simple liquids. For example, unlike most other substances, a certain mass of water takes up more space in the solid state (ice) than in liquid, due to the fact that its molecules comprises a specific regular structure. Another example is the surface tension of liquid water, which is two times more than other non-polar, more simple liquids.
The water is quite simple, but not too much. This means that the only explanation manifested additional phase of water is that it behaves a bit like a liquid crystal. Hydrogen bonds between the molecules maintain a certain order at low temperatures, but can also come in a more free state with increasing temperature. This explains the significant deviations observed by scientists during the research.
If all are confirmed, the conclusions of the authors can find a variety of uses. For example, if changes in the environment (say, temperature) entail changes in the physical properties of matter, theoretically it is possible to use to create instruments of sensing. Or can be approached more fundamentally, the biological systems consist mainly of water. How the organic molecules (e.g. proteins) interact with each other, probably depends on how water molecules form a liquid phase. If you understand how water molecules behave on average, at different temperatures, it is possible to clarify how they interact in biological systems.
This is a great opportunity for theorists and experimentalists, as well as a perfect example that sometimes the usual stuff can hide his secrets.
