Among vast set of substances water occupies a completely special place. And it should be understood literally. Almost all physico-chemical properties of water are exceptions in nature: it is really the most surprising substance in the world. Surprising not only because of variety of the isotope forms of a molecule and not only because of hopes, which are connected to it as with a source of energy of the future. It is surprising by its most usual properties.
Let's not doubt in a law. Water is the rarest, and, maybe, unique exception to the rules. Perhaps, there is no substance more surprising and mysterious, than ordinary water. But it is not possible yet to explain the reason of it up to the end of, though it is clear, that the secrets of water are hidden in a structure of its molecule and intermolecular structure.
The fact that usual water represents still rather bad investigated substance, is explained not only by the complexity and uncertainty of its structure, but also by that, it is a liquid substance. It is much easier, to investigate firm substance or gas rather than liquid substance, as in the first molecules are precisely ordered, and in second they weekly cooperate and have large freedom of movement. The is no answer to a question, why there are two forms of the condition of substance, condensed from gas,- liquid and firm, - close on density and energy of intermolecular interaction and enormously distinguished on kinetics of intermolecular interaction. There is no theory, which would adequately describe a liquid condition. The is also no theory of melting - of change from the order to the disorder in systems with close density and energies of intermolecular interaction. That is why, for example, the ice is investigated better, than water. An absolutely clean water is not also received in laboratories yet, its properties remain a secret till now.
Characteristic |
Anomaly |
Role |
| volatility | Least among combinations of hydrogen with elements of a subgroup of oxygen | essential to physiology of a cell: slow decrease of humidity of various materials |
| The latent heat of melting and evaporation | The latent heat of melting and evaporation | Thermostatic effect in technological processes, carry of heat by water streams in a nature, promotes preservation of constant temperature of a body |
| Temperature of freezing | highest, except for ammonia | Thermostatic effect at a point of freezing. Very important for preservation of thermal and water balance in an atmosphere. |
| Temperature of boiling | highest of all liquids | Large expenses of heat for evaporation in productions; the economy is possible at utilization of heat, isolated at condensation of steam. |
| Heat-conductivity | highest of all liquids | Plays a role in heat exchanging equipment and in small scale processes, for example passing in cells |
| The surface-tension | The surface-tension | essential for physiology of a cell, defines the superficial phenomena in technology |
| dielectric penetrability | the highest of all liquids | essentially influence electrolyte dissociation |
| The solubility | Dissolves many substances in more quantities, than other liquids | the main solvent in techniques, links the physical and biological phenomena |
| Density | Greatest at + 4 °C | At reservoir freezing, the lower level of water, as the heaviest, is at + 4 °C temperature. Thus water in alive creatures does not freeze also |
| The viscosity | Decreases at increase of pressure | Provides the large mobility deeply in entrails of the earth, where the pressure reaches its great meanings |
| Specific heat | highest, except for ammonia and hydrogen |
