The most important substance

Water- one of the most common substances on Earth. Water occupies most of the surface of our planet.
Water occurs naturally in three states: liquid, solid (ice and snow), gaseous (water vapor).
Water turns to ice at 0 degrees.
Water vapor is constantly present in the air. But it cannot be seen because it is a transparent, colorless gas. It gets into the air due to the fact that water constantly evaporates from the surface of reservoirs and soil.
For living organisms, water has great value. It is part of living organisms. Any organism constantly consumes water and needs to replenish it. Therefore, water is essential for all plants and animals. A person needs more than 2 liters of water per day.

Practical work "Investigation of the properties of water"
The purpose of the work: to determine the properties of water.

Consider equipment prepared for practical work. Indicate the names of objects with arrows.

Experience 1. Dip a glass rod into a glass of water. Is she visible? What property of water is this talking about?
Conclusion: Water is clear
Experience 2. Compare the color of the water with the color of the stripes shown on this page. What do you see? What does it say?


Conclusion: Water is colorless
Experience 3. Smell the clean water. What property of water can be established in this way?
Conclusion: Water has no odor
Experience 4. Immerse a flask with a tube filled with colored water in hot water. What are you watching? What does this indicate?

Conclusion: When heated, water expands.
Experience 5. Place the same flask on ice. What are you watching? What does this indicate?

Conclusion: As water cools, it contracts.
General conclusion: water is transparent, colorless, odorless, expands when heated, contracts when cooled.

Whereas, it is likely that you remember that for all other substances, their solid phase is heavier than the liquid phase.

Accordingly, it's good that ice is lighter than water - and this is also the main property of water, thanks to which life in its current form is possible.

Well, if this property of water did not exist, we would have to develop on the basis of, for example, ammonia. That's more fun 🙂

Now let's focus on the fact that water can evaporate when boiling. But this is not the main property of water - since almost any substance evaporates during boiling, and there is nothing shameful in this. The important thing is that water evaporates and just in a liquid state, and even from the surface of the ice. Why is this property more important than boiling evaporation? Here's why.

The fact that water can evaporate not only when boiling is the main property of water, because it is possible water cycle in nature. Which is definitely good, since water does not accumulate in one place, but more or less evenly diverges throughout the planet. That is, roughly speaking, in the Sahara desert it is not as hot and dry as it could be, because in Antarctica water evaporates from the surface of glaciers. Well, the oceans play an important role in this.

Accordingly, without the water cycle in nature, life would sit near a couple of oases, and the rest of the places would be an arid desert, where there is not a drop of moisture.

And therefore the property of water to evaporate is the main property of water.

Naturally, not only water can evaporate without boiling. Majority aromatic compounds(alcohols, ethers, chloroform, etc.) do not evaporate when boiling. But water has one important plus, one more main property - water is not toxic to living organisms. Whereas alcohols and ethers are toxic. By the way, more about toxicity (and how to deal with it) ethyl alcohol, that is, vodka, in the article "Positive properties of structured vodka".

Of course, in modern conditions and water can become toxic. But it's handled for water, and it's not a big problem that can't be dealt with.

So, another main property of water is that it is non-toxic.

Otherwise, we would, again, be different 🙂

And, finally, the main property of water, which is important not only for life, but also for industry: water heats up rather slowly and cools down slowly (that is, can absorb a lot of heat). This property protects people and other animals, and the Earth, from overheating. And hypothermia. That is why living organisms can survive at -50 degrees Celsius and at + 50 degrees. If we were built on the basis of another substance, such a range of temperatures would not be within our reach.

In addition, it must be taken into account that warm and cold water have different weight Warm water is lighter, cold water is heavier. Accordingly, in the ocean there is a stratification of water - both in salinity and in temperature. And in the ocean such life as it is now organized is possible. Well, since we all came out of the ocean, if it were not for this property of water, then we would also be completely different.

And finally, the property of water to absorb heat and be on the surface in a heated state allows the existence of such things as warm currents - and in particular, the Gulf Stream. Which heats the whole of Europe, and without which in place of Europe there would be tundra with taiga, and not vineyards.

Perhaps you can name some other basic properties of water, but those listed above, in my opinion, are truly fundamental, since the existence of life on the planet depends on them in the form in which life exists. I hope this information will be useful to you when you need to answer the questions of curious children 🙂

And here is the promised presentation on the topic "Basic properties of water" for download: http://festival.1september.ru/articles/513123/

So, the main properties of water are the properties due to which we are all alive!

And we have the look and shape that we have 🙂

other substances are completely insoluble in water

Water is the most unique substance, the basis of all living organisms on the planet. It can take various forms and be in three states. What are the main physical and Chemical properties water? It is about them that we will discuss in our article.

Water is...

Water is the most abundant on our planet inorganic compound. The physical and chemical properties of water are determined by the composition of its molecules.

Thus, the structure of a water molecule contains two hydrogen atoms (H) and one oxygen atom (O). Under normal environmental conditions, it is a tasteless, odorless and colorless liquid. Water can also be in other states: in the form of steam or in the form of ice.

More than 70% of our planet is covered by water. Moreover, about 97% falls on the seas and oceans, so most of it is not suitable for human consumption. What are the main chemical properties drinking water- you will learn further.

Water in nature and human life

Water is an essential component of any living organism. In particular, the human body, as is known, consists of more than 70% of water. Moreover, scientists suggest that it was in this environment that life on Earth originated.

Water is contained (in the form of water vapor or droplets) in different layers of the atmosphere. It comes to the earth's surface from the atmosphere in the form of rain or other precipitation (snow, dew, hail, hoarfrost) through condensation processes.

Water is the object of research for a number of scientific disciplines. Among them are hydrology, hydrography, hydrogeology, limnology, glaciology, oceanology and others. All these sciences, one way or another, study the physical and chemical properties of water.

Water is actively used by man in his economic activities, in particular:

• for growing crops;
• in industry (as a solvent);
• in the energy sector (as a coolant);
• to extinguish fires;
• in cooking;
• in pharmacy and so on.

Of course, in order to effectively use this substance in economic activity, the chemical properties of water should be studied in detail.

Varieties of water

As mentioned above, water in nature can be in three states: liquid (actually, water), solid (ice crystals) and gaseous (steam). It can also take on any form.

There are several types of water. So, depending on the content of Ca and Na cations, water can be:

• hard;
• soft.

• fresh;
• mineral;
• brackish.

In esotericism and some religions there is water:

• dead;
• live;
• saint.

In chemistry, there are also such concepts as distilled and deionized water.

The formula of water and its biological significance

Hydrogen oxide is what chemists call this substance. The formula for water is: H 2 O. It means that this compound consists of one oxygen atom and two hydrogen atoms.

The unique chemical properties of water determined its exceptional role for the life of living organisms. It is thanks to water that biological life exists on our planet.

The most unique feature of water is that it perfectly dissolves great amount other substances (both organic and inorganic origin). An important consequence of this feature is that all chemical reactions in living organisms proceed quite quickly.

In addition, thanks to unique properties water, it is in a liquid state, with an extremely wide temperature range.

Physical properties of water

Thanks to unique hydrogen bonds, water, under standard environmental conditions, is in a liquid state. This explains the extremely high boiling point of water. If the molecules of a substance were not bound by these hydrogen bonds, then the water would boil at +80 degrees, and freeze - as much as -100 degrees.

Water boils at +100 degrees Celsius, and freezes at zero degrees. True, under certain, specific conditions, it can begin to freeze even at positive temperatures. When water freezes, it expands in volume (due to a decrease in density). By the way, this is almost the only substance in nature that has a similar physical property. In addition to water, only bismuth, antimony, germanium and gallium expand upon freezing.

The substance is also characterized by high viscosity, as well as a rather strong surface tension. Water is an excellent solvent for polar substances. You should also know that water conducts electricity through itself very well. This feature is explained by the fact that in water there is almost always a large number of salt ions dissolved in it.

Chemical properties of water (grade 8)

Water molecules have extremely high polarity. Therefore, this substance in reality consists not only of simple H 2 O molecules, but also of complex aggregates (formula - (H 2 O) n).

Chemically, water is very active, it reacts with many other substances, even at ordinary temperatures. When interacting with oxides of alkali and alkaline earth metals, it forms bases.

Water is also capable of dissolving a wide range of chemical substances- salts, acids, bases, some gases. For this property, it is often called a universal solvent. All substances, depending on whether they dissolve in water or not, are usually divided into two groups:

• hydrophilic (dissolves well in water) - salts, acids, oxygen, carbon dioxide etc.;
• hydrophobic (poorly soluble in water) - fats and oils.

Water also enters into chemical reactions with some metals (for example, sodium), and also takes part in the process of plant photosynthesis.

Finally...

Water is the most abundant inorganic substance on our planet. It is found almost everywhere: on the earth's surface and in its depths, in the mantle and in rocks, in the high layers of the atmosphere, and even in space.

The chemical properties of water are determined by its chemical composition. It belongs to the group of chemical active substances. With many substances, water enters into

Water is physiologically necessary for the cytoplasm of any cell, therefore it is limiting factor both for terrestrial organisms and for those living in water, if in the latter case its amount is subject to sharp changes (ebb and flow) or it is lost by the body in very salty water by osmosis.

In the ground-air environment, this abiotic factor is characterized by the amount of precipitation, humidity, drying properties of the air, and the available area of ​​water reserves.

The amount of precipitation depends on physical and geographical conditions and is unevenly distributed around the globe. For organisms, the most important limiting factor is the distribution of precipitation by season. In temperate latitudes, even with a sufficient amount of total annual precipitation, their uneven distribution can lead to the death of plants from drought or, conversely, from waterlogging. In the tropical zone, organisms have to experience wet and dry seasons that regulate their seasonal activity at a temperature that is almost constant throughout the year.

Air humidity It is usually measured in terms of relative humidity (the percentage of the actual water vapor pressure to the saturated vapor pressure at the same temperature). The amount of humidity affects temperature effects: lowering the humidity below a certain limit at a given temperature leads to a drying effect of the air.

The drying effect of air is most important for plants. The vast majority of plants absorb water from the soil through the root system. Dry soil makes absorption difficult. Plants adapt to the drying of the soil by increasing the suction power and the active surface of the root system.

Water is consumed for photosynthesis, about 0.5% of water is absorbed by cells, and 97 - 99% of it is spent on transpiration - evaporation of water through foliage. With sufficient water and nutrients, plant growth is proportional to transpiration. The main form of plant adaptation to soil desiccation is not a decrease in transpiration, but the cessation of growth during the drought period.

Depending on the ways in which plants adapt to humidity, there are several environmental groups, for example: hygrophytes- land plants that live in very wet soils and in conditions of high humidity (rice), mesophytes- plants that can tolerate a slight drought (woody plants of various climatic zones, herbaceous plants of oak forests, etc.), xerophytes- plants of dry steppes and deserts. Xerophytes, in turn, are divided into succulents- plants capable of accumulating moisture in fleshy leaves and stems (aloe, cacti), and sclerophytes- plants with a high suction capacity of the root system and the ability to reduce transpiration due to narrow small leaves.

There is a phenomenon among succulents convergence- plants related to different types, have almost the same shape: African spurge and cactus have a spherical shape, providing a minimum evaporation surface.

Among animals, in relation to water, they distinguish their environmental groups: hygrophiles(moisture-loving), mesophiles- intermediate group and xerophiles(dry-loving). Ways of regulation of water balance in animals are divided into behavioral, morphological and physiological.

TO behavioral ways include migration to more humid places, periodic visits to a watering place, the transition to a nocturnal lifestyle, etc. morphological ways of adaptation- devices that retain water in the body: shells of land snails, horny covers in reptiles, etc. physiological adaptations provide education metabolic water, which is the result of metabolism and allows the body to do without drinking water. The latter method of adaptation is used by such animals as camels, sheep, dogs, which withstand water losses in significant quantities (camels - up to 27%). A person dies already with a 10% loss of water. Poikilothermic animals tolerate water loss better because they do not have to use water to cool the body, as homeothermic animals do.