Water is the main condition for life on Earth. More than two-thirds of the earth's surface consists of oceans, seas, rivers and lakes. The volume of water in the oceans is ten times the volume of all land.
Earth - an island in the oceans
Our planet can be considered the ocean, in which the continents are actually only huge islands, it is because of this that from the near-earth orbit the Earth seems green-blue, the color of the ocean.
Every living creature on our planet consists of water, for example, jellyfish contains 95% of it, and the human body contains 65% of water. The lack of this substance in only 1% of body weight causes a feeling of thirst. If the body loses 10% moisture, this can lead to its death. Almost all chemical reactions occur in an aqueous medium. Evaporating, the water regulates the temperature of the inhabitants of the land. If a person had not sweated, then after an hour of hard work his body temperature would have risen to 46 ° C.
Water dynamics
The aquatic environment is in constant motion: it evaporates from open water, gathers in clouds, falls in the form of rain or snow, and then streams to the sea in streams, rivers and streams. Moisture seeps into the ground, accumulates and again comes to the surface, where it replenishes water bodies. Most of the water exists in the form of vapor in the atmosphere, in the solid state - in the form of huge layers of snow and ice in the mountains, and in the polar regions. About a twentieth of rainwater is consumed directly by living organisms. Natural water is never absolutely clean, rain is considered to be as pure as possible, but it also contains some impurities trapped from the air.
The figure shows what atoms a water molecule consists of and how it divides by nature.
Water structure
What atoms a water molecule is divided into - any schoolchild today knows.
Each molecule of this substance is built from one oxygen atom and two hydrogen atoms. This is a structure of three elements, as if pressed to each other. In the middle is an oxygen atom (chemical symbol - O), two hydrogen atoms (H) are attached on both sides - these are atoms into which water molecules are divided.
Negative charges are formed near the oxygen atom, and positive ones around the hydrogen atoms. Knowing what atoms a water molecule is divided into, physics determines that its molecule is a dipole. This explains all of her physical properties. The distances between the nuclei of O, H atoms are about 0.1 nm, and between the hydrogen atoms - about 0.15 nm.
In fact, water is hydrogen oxide, the main substance on Earth. In 1783, the famous chemist Lavoisier first produced hydrogen from water, which showed what atoms the water molecule divides into (formula - H 2 O). Hence its molecular weight - 18 g / mol, consisting of the sum of the atomic masses of oxygen and hydrogen present in the molecule. The structural formula shows which atoms the water molecule divides into.
Physics about water
Water is a liquid that has no smell, no taste, no color, with the following properties:
- the density of water is 1 g / cm 3 ;
- freezing degree - 0 (ice);
- boiling degree - 100 (steam).
What atoms the water molecule divides in physics can be seen in the following figure.
Upon boiling, the hydrogen bonds break, and the liquid becomes a vapor. When the temperature decreases from 100 ° C to 3.98 ° C, its volume constantly decreases. But with further passage of the lower boundary, the reverse process occurs. Part of the volume of water at 3.98 ° C has a greater mass than at 0 ° C, because of this the ice is held on its surface.
In addition, water has the highest surface tension compared to other liquid substances, excluding mercury. Under the surface, water molecules have a strong attraction between themselves. But these molecules do not attract air molecules above them, they are attracted only among themselves. This surface tension creates a film effect on water.
This property is used by some insects that can walk on the surface without diving. Their bodies are very light, and surface tension does not allow them to fall under water. The formation of icicles also occurs due to this property of water and the attraction between its molecules. When a liquid turns into steam, that is, a gaseous substance, the surface tension disappears.
Chemical properties of water
Water is a fairly reactive substance. Its chemical properties depend on what atoms the water molecule divides into. The liquid decomposes into hydrogen and oxygen under the influence of an electric current. A reaction occurs in which it acts as an oxidizing agent and a reducing agent. A water molecule is similar to a very strong atomic magnet and can bind to almost anything that can attach. Under its action, hydrolysis of salts is observed to produce a weak electrolyte.
Water reacts with most basic oxides. Reacts with many metals, for example, with sodium, potassium and when heated with iron, while hydrogen evolution is observed:
2Na + 2H 2 O = H 2 + 2NaOH;
2K + 2H 2 O = H 2 + 2KOH;
3Fe + 4H 2 O = 4H 2 + Fe 3 O 4 .
Non-metals are not as active as metals, but still interact with water with strong heating:
C + H 2 O = H 2 + CO;
CH 4 + 2H 2 O = 4H 2 + CO 2 .
Interacts with many non-metal oxides. In this case, reactions of the compound occur, forming acids.
It is obtained by burning hydrogen in oxygen with the formation of water vapor:
2H 2 + O 2 = 2H 2 O,
moreover, this reaction occurs instantly at a temperature of 700 about C.
The principle of dissolution in water
Many substances that differ in their state of aggregation can dissolve in an aqueous medium. They are divided into the following types:
- soluble;
- poorly soluble;
- almost insoluble.
What is the principle of dissolution? Given what atoms a water molecule divides into, its ability to attract molecules of different substances can be explained. When interacting with it, salt ions will be attracted by charged ions of a water molecule. In this case, heat is released or absorbed. Ions of a substance dissolved in water hold a certain number of water molecules, thus forming a hydration shell. Ions become hydrated, and such crystals are called crystalline hydrates.
Water functionality
It is difficult to overestimate the functions of water substance in the lives of the inhabitants of our planet, because all living things not only consist of it, but also constantly support their existence only thanks to this substance.
- Metabolism. Water acts as a polar solvent, the best medium for all reactions occurring in a living organism. Substances that can dissolve in it are called hydrophilic, and insoluble - hydrophobic.
- Transport. The internal molecules of a cell are constantly moving from one cell to another. Water is the most important transfer in the internal environment of any organisms.
- Thermoregulation. Water evenly distributes heat and cold, regulating the temperature inside the body, for example, causing perspiration in animals, thereby cooling the body.
- The biological value of water is that it is involved in many chemical reactions of the body.
- Mechanical function. The property of water not shrink is important to maintain the shape of organs and tissues.
Unusual properties of water
There is no substance on Earth more significant for all living things than simple water. Variable density, high heat capacity and high surface tension, its ability to memory - all these are abnormal properties of such a substance as water. Observations and experiments prove that an aqueous substance has the ability to absorb the properties of materials that once dissolved in it, and to store these properties, even after the complete removal of these materials. The basic principles of homeopathic medicine are built on this. And one more indisputable and at the same time inexplicable fact from the point of view of science is the unique healing properties of Epiphany water containing enormous energy. All these puzzles are still to be solved by modern and future scientists.