The formulas for covalent bonds are fundamentally different from the formulas for ionic bonds. The fact is that covalent compounds can be formed in a variety of ways, therefore, as a result of the reaction, the appearance of various compounds is possible.

1. Empirical formula

The empirical formula indicates the elements that make up the molecule, with the smallest integer ratios.

For example, C 2 H 6 O - the compound contains two carbon atoms, six hydrogen atoms and one oxygen atom.

2. Molecular formula

The molecular formula indicates what atoms the compound consists of and in what quantities these atoms are in it.

For example, for the compound C 2 H 6 O molecular formulas can be: C 4 H 12 O 2 ; C 6 H 18 O 3 ...

For full description a covalent compound of the molecular formula is not enough:

As you can see, both connections have the same molecular formula- C 2 H 6 O, but they are completely different substances:

• dimethyl ether is used in refrigeration;
• ethyl alcohol is the basis of alcoholic beverages.

3. Structural formula

The structural formula serves to accurately determine the covalent compound, because, in addition to the elements in the compound and the number of atoms, it also shows link diagram connections.

The structural formula is electron point formula And Lewis formula.

4. Structural formula for water (H 2 O)

Consider the procedure for constructing a structural formula using the example of a water molecule.

I We build the connection frame

The atoms of the compound are arranged around the central atom. As the central atoms usually act: carbon, silicon, nitrogen, phosphorus, oxygen, sulfur.

II Find the sum of valence electrons of all atoms of the compound

For water: H 2 O \u003d (2 1 + 6) \u003d 8

There is one valence electron in the hydrogen atom, and 6 in the oxygen atom. Since there are two hydrogen atoms in the compound, the total number of valence electrons of the water molecule will be 8.

III Determine the number of covalent bonds in a water molecule

We determine by the formula: S=N-A, Where

S is the number of electrons shared in the molecule;

N- the sum of valence electrons corresponding to the completed external energy level of atoms in the compound:

N=2- for the hydrogen atom;

N = 8- for atoms of other elements

A is the sum of the valence electrons of all atoms in the compound.

N = 2 2 + 8 = 12

A = 2 1 +6 = 8

S=12 - 8=4

There are 4 shared electrons in a water molecule. Since a covalent bond consists of a pair of electrons, we get two covalent bonds.

IV We distribute joint electrons

There must be at least one bond between the central atom and the atoms that surround it. For a water molecule, there will be two such bonds for each hydrogen atom:

V Distribute the remaining electrons

Of the eight valence electrons, four have already been distributed. Where to "put" the remaining four electrons?

Each atom in a compound must have a full octet of electrons. For hydrogen, these are two electrons; for oxygen - 8.

The shared electrons are called binding.

The electron point formula and the Lewis formula clearly describe the structure of a covalent bond, but they are cumbersome and take up a lot of space. These shortcomings can be avoided by using compressed structural formula , which indicates only the order of "following" links.

An example of a compressed structural formula:

• dimethyl ether - CH 3 OCH 3
• ethyl alcohol - C 2 H 5 OH

Of the oxides of hydrogen, the most common on Earth is water. Empirical formula - H2O. Molecular weight - 18. The structure of the water molecule(structural formula):

Water molecules have a triangular formula: hydrogen atoms form an angle of 104.3% with an oxygen atom. Near the oxygen atom, a negatively charged field is formed, since the highest electron density is concentrated on the oxygen atom, and near the hydrogen atoms, a positively charged field is formed - a water molecule - a dipole. Due to polarity, water molecules associate by forming hydrogen bonds. The latter determine everything physical properties water.

Physical properties: water is a colorless liquid, odorless and tasteless, density 1 g/cm3; freezing point - 0 °C (ice), boiling point - 100 °C (steam). At 100 °C and normal pressure, hydrogen bonds break and water passes into a gaseous state - steam. Water has poor thermal and electrical conductivity, but good solubility.

Chemical properties: water slightly dissociates:

In the presence of water, hydrolysis of salts occurs - their decomposition by water with the formation of a weak electrolyte:

Interacts with many basic oxides, metals:

With acidic oxides:

Receipt: water is formed by the combustion of hydrogen in oxygen: 2H2 + O2 = 2H2O

This reaction proceeds instantaneously at 700 °C. A mixture of two volumes of hydrogen and one volume of oxygen is called explosive mixture. Distillation produces pure water distilled water.

Finding in nature: Water makes up 2/3 of the Earth's surface. Natural water is never pure, because a huge amount of salts are dissolved in it. Water is part of many crystalline hydrates: Na2CO3? 10H2O; CuSO4? 5H2O; MgSO4? 7H2O. Heavy water D2O differs from the usual one formed by hydrogen - protium - by the presence of a second isotope of hydrogen in it - D(deuterium), whose Ar is 2, therefore, molecular mass heavy water - 20. Density D2O = 1.1050 g/cm3; boiling point - 101.4 ° C, freezing point - 3.8 ° C. Chemically less active. Used as a neutron moderator in nuclear reactors. It is unsuitable for life processes, because it changes the rate of biochemical reactions. Ordinary water contains some heavy water.

Water (hydrogen oxide) - binary inorganic compound with the chemical formula H 2 O. The water molecule consists of two hydrogen atoms and one oxygen, which are interconnected by a covalent bond.

Hydrogen peroxide.

Physical and chemical properties

Physical and Chemical properties waters are determined by the chemical, electronic and spatial structure of H 2 O molecules.

The H and O atoms in the H 2 0 molecule are in their stable oxidation states, respectively +1 and -2; therefore, water does not exhibit pronounced oxidizing or reducing properties. Please note: in metal hydrides, hydrogen is in the -1 oxidation state.

The H 2 O molecule has an angular structure. H-O bonds very polar. There is an excess negative charge on the O atom, and excess positive charges on the H atoms. In general, the H 2 O molecule is polar, i.e. dipole. This explains the fact that water is a good solvent for ionic and polar substances.

The presence of excess charges on H and O atoms, as well as unshared electron pairs at O ​​atoms, causes the formation of hydrogen bonds between water molecules, as a result of which they combine into associates. The existence of these associates explains the anomalously high values ​​of mp. etc. kip. water.

Along with the formation of hydrogen bonds, the result of the mutual influence of H 2 O molecules on each other is their self-ionization:
in one molecule there is a heterolytic break of the polar O-N connections, and the released proton joins the oxygen atom of another molecule. The resulting hydroxonium ion H 3 O + is essentially a hydrated hydrogen ion H + H 2 O, therefore, the water self-ionization equation is simplified as follows:

H 2 O ↔ H + + OH -

The dissociation constant of water is extremely small:

This indicates that water very slightly dissociates into ions, and therefore the concentration of undissociated H 2 O molecules is almost constant:

In pure water, [H + ] = [OH - ] = 10 -7 mol / l. This means that water is a very weak amphoteric electrolyte that exhibits neither acidic nor basic properties to a noticeable degree.
However, water has a strong ionizing effect on the electrolytes dissolved in it. Under the action of water dipoles, polar covalent bonds in the molecules of solutes turn into ionic ones, the ions are hydrated, the bonds between them are weakened, resulting in electrolytic dissociation. For example:
HCl + H 2 O - H 3 O + + Cl -

(strong electrolyte)

(or excluding hydration: HCl → H + + Cl -)

CH 3 COOH + H 2 O ↔ CH 3 COO - + H + (weak electrolyte)

(or CH 3 COOH ↔ CH 3 COO - + H +)

According to the Bronsted-Lowry theory of acids and bases, in these processes, water exhibits the properties of a base (proton acceptor). According to the same theory, water acts as an acid (proton donor) in reactions, for example, with ammonia and amines:

NH 3 + H 2 O ↔ NH 4 + + OH -

CH 3 NH 2 + H 2 O ↔ CH 3 NH 3 + + OH -

Redox reactions involving water

I. Reactions in which water plays the role of an oxidizing agent

These reactions are possible only with strong reducing agents, which are able to reduce the hydrogen ions that are part of the water molecules to free hydrogen.

1) Interaction with metals

a) Under normal conditions, H 2 O interacts only with alkali. and alkali-earth. metals:

2Na + 2H + 2 O \u003d 2NaOH + H 0 2

Ca + 2H + 2 O \u003d Ca (OH) 2 + H 0 2

b) At high temperatures, H 2 O also reacts with some other metals, for example:

Mg + 2H + 2 O \u003d Mg (OH) 2 + H 0 2

3Fe + 4H + 2 O \u003d Fe 2 O 4 + 4H 0 2

c) Al and Zn displace H 2 from water in the presence of alkalis:

2Al + 6H + 2 O + 2NaOH \u003d 2Na + 3H 0 2

2) Interaction with non-metals having low EO (reactions occur under harsh conditions)

C + H + 2 O \u003d CO + H 0 2 ("water gas")

2P + 6H + 2 O \u003d 2HPO 3 + 5H 0 2

In the presence of alkalis, silicon displaces hydrogen from water:

Si + H + 2 O + 2NaOH \u003d Na 2 SiO 3 + 2H 0 2

3) Interaction with metal hydrides

NaH + H + 2 O \u003d NaOH + H 0 2

CaH 2 + 2H + 2 O \u003d Ca (OH) 2 + 2H 0 2

4) Interaction with carbon monoxide and methane

CO + H + 2 O \u003d CO 2 + H 0 2

2CH 4 + O 2 + 2H + 2 O \u003d 2CO 2 + 6H 0 2

Reactions are used in industry to produce hydrogen.

II. Reactions in which water acts as a reducing agent

These reactions are possible only with very strong oxidizing agents that are capable of oxidizing oxygen CO CO -2, which is part of water, to free oxygen O 2 or to peroxide anions 2-. In an exceptional case (in reaction with F 2), oxygen is formed with c o. +2.

1) Interaction with fluorine

2F 2 + 2H 2 O -2 \u003d O 0 2 + 4HF

2F 2 + H 2 O -2 \u003d O +2 F 2 + 2HF

2) Interaction with atomic oxygen

H 2 O -2 + O \u003d H 2 O - 2

3) Interaction with chlorine

At high T, a reversible reaction occurs

2Cl 2 + 2H 2 O -2 \u003d O 0 2 + 4HCl

III. Reactions of intramolecular oxidation - reduction of water.

Under the action of an electric current or high temperature, water can be decomposed into hydrogen and oxygen:

2H + 2 O -2 \u003d 2H 0 2 + O 0 2

Thermal decomposition is a reversible process; the degree of thermal decomposition of water is low.

Hydration reactions

I. Hydration of ions. Ions formed during the dissociation of electrolytes in aqueous solutions, attach a certain number of water molecules and exist as hydrated ions. Some ions form such strong bonds with water molecules that their hydrates can exist not only in solution, but also in the solid state. This explains the formation of crystalline hydrates such as CuSO4 5H 2 O, FeSO 4 7H 2 O, etc., as well as aqua complexes: CI 3 , Br 4 , etc.

II. Hydration of oxides

III. Hydration organic compounds containing multiple bonds

Hydrolysis reactions

I. Hydrolysis of salts

Reversible hydrolysis:

a) according to the salt cation

Fe 3+ + H 2 O \u003d FeOH 2+ + H +; (acidic environment. pH

b) by salt anion

CO 3 2- + H 2 O \u003d HCO 3 - + OH -; (alkaline environment. pH > 7)

c) by the cation and by the anion of the salt

NH 4 + + CH 3 COO - + H 2 O \u003d NH 4 OH + CH 3 COOH (environment close to neutral)

Irreversible hydrolysis:

Al 2 S 3 + 6H 2 O \u003d 2Al (OH) 3 ↓ + 3H 2 S

II. Hydrolysis of metal carbides

Al 4 C 3 + 12H 2 O \u003d 4Al (OH) 3 ↓ + 3CH 4 netane

CaC 2 + 2H 2 O \u003d Ca (OH) 2 + C 2 H 2 acetylene

III. Hydrolysis of silicides, nitrides, phosphides

Mg 2 Si + 4H 2 O \u003d 2Mg (OH) 2 ↓ + SiH 4 silane

Ca 3 N 2 + 6H 2 O \u003d ZCa (OH) 2 + 2NH 3 ammonia

Cu 3 P 2 + 6H 2 O \u003d ZCu (OH) 2 + 2PH 3 phosphine

IV. Hydrolysis of halogens

Cl 2 + H 2 O \u003d HCl + HClO

Br 2 + H 2 O \u003d HBr + HBrO

V. Hydrolysis of organic compounds

Water is one of the main substances that ensure the existence of the planet and mankind. This is a completely unique element, without which the life of any living being is impossible. Some chemical and physical properties of water are unique.

The importance of this substance is difficult to overestimate. Water occupies most of the planet, forms oceans, seas, rivers and other bodies of water. It is directly involved in the formation of climate and weather, thereby providing certain conditions for existence in one or another corner of the planet.

For many organisms, it serves as a habitat. In addition, almost every living being in one way or another consists of water. For example, its content in the human body is from 70 to 90 percent.

Physical properties of water: a brief description of

The water molecule is unique. Its formula is probably known to everyone: H2O. But some of the physical properties of water directly depend on the structure of its molecule.

In nature, water exists immediately in three. Under normal conditions, it is colorless, odorless and tasteless. When the temperature drops, the water crystallizes and turns into ice. When the temperature rises, the liquid turns into a gaseous state - water vapor.

Water is characterized by a high density, which is approximately 1 gram per cubic centimeter. Water boils when the temperature rises to 100 degrees Celsius. But when the temperature drops to 0 degrees, the liquid turns into ice.

Interestingly, the decrease atmospheric pressure causes a change in these indicators - water boils at a lower temperature.

The thermal conductivity of water is approximately 0.58 W/(m*K). Another important indicator is its high, which is almost equal to the corresponding indicator for mercury.

Unique physical properties of water

As already mentioned, it is water that ensures the normal existence of the planet, affecting the climate and the vital activity of organisms. But this substance is actually unique. It is these amazing properties of water that provide life.

Take, for example, the density of ice and water. In most cases, when freezing, the molecules of substances are closer to each other, their structure becomes more compact and denser. But this scheme does not work with water. For the first time this amazing property was described by Galileo.

If you slowly lower the temperature and follow it, then at first the scheme will be quite standard - the substance will become denser and more compact. Changes will occur after the temperature reaches +4 degrees. At this rate, the water suddenly becomes lighter. That is why ice floats on the surface of the water, but does not sink. By the way, this feature ensures the survival of aquatic flora and fauna - water rarely freezes completely, keeping its inhabitants alive.

By the way, when freezing, the substance expands by about 9%. This feature of water causes natural corrosion of rocks. On the other hand, this is why water pipes burst during an unexpected cold snap.

But that's not all. Another unique feature is its anomalously high heat capacity. For example, the amount of heat that is needed to heat one gram of water by one degree is enough to heat about 10 g of copper or 9 g of iron.

The entire world ocean is a global thermostat that smooths out temperature fluctuations, both daily and annual. By the way, the same properties are endowed and which is contained in the atmosphere. It's no secret that the desert is characterized by sharp temperature changes - it is too hot during the day, and very cold at night. This is due precisely to dry air and the lack of the required amount of water vapor.

Strictly speaking, in this article we will briefly consider not only chemical and physical properties of liquid water, but also the properties inherent in it in general as such.

You can find more information about the properties of water in the solid state in the article - PROPERTIES OF WATER IN THE SOLID STATE (read →).

Water is a super-significant substance for our planet. Without it, life on Earth is impossible; not a single geological process takes place without it. The great scientist and thinker Vladimir Ivanovich Vernadsky wrote in his works that there is no such component, the value of which could "compare with it in terms of its influence on the course of the main, most formidable geological processes." Water is present not only in the body of all living beings on our planet, but also in all substances on Earth - in minerals, in rocks ... The study of the unique properties of water constantly reveals more and more secrets to us, sets us new mysteries and throws new challenges.

Anomalous properties of water

Many physical and chemical properties of water surprise and fall out of general rules and regularities and are anomalous, for example:

• In accordance with the laws established by the principle of similarity, within the framework of such sciences as chemistry and physics, we might expect that:
  • water will boil at minus 70°C, and freeze at minus 90°C;
  • water will not drip from the tip of the tap, but will flow in a thin stream;
  • ice will sink rather than float on the surface;
  • more than a few grains of sugar would not dissolve in a glass of water.
• The water surface has a negative electrical potential;
• When heated from 0°C to 4°C (3.98°C to be exact), water contracts;
• The high heat capacity of liquid water is surprising;

As noted above, in this material we list the main physical and chemical properties of water and make brief comments on some of them.

Physical properties of water

PHYSICAL PROPERTIES are properties that appear outside of chemical reactions.

Water purity

The purity of water depends on the presence of impurities, bacteria, salts of heavy metals in it ..., to get acquainted with the interpretation of the term PURE WATER according to our website, you need to read the article PURE WATER (read →).

water color

The color of the water depends on chemical composition and mechanical impurities

For example, let's take the definition of "Colors of the Sea", given by the "Great Soviet Encyclopedia".

The color of the sea. The color perceived by the eye when the observer looks at the surface of the sea. The color of the sea depends on the color of sea water, the color of the sky, the number and nature of clouds, the height of the Sun above the horizon, and other reasons.

The concept of the color of the sea should be distinguished from the concept of the color of sea water. The color of sea water is understood as the color perceived by the eye when viewing sea water vertically over a white background. Only an insignificant part of the light rays incident on it is reflected from the sea surface, the rest of them penetrate deep into, where they are absorbed and scattered by water molecules, particles of suspended matter and the smallest gas bubbles. The scattered rays reflected and emerging from the sea create the C. m. Water molecules scatter blue and blue most of all. green rays. Suspended particles scatter all rays almost equally. Therefore, sea water with a small amount of suspended matter appears blue-green (the color of the open parts of the oceans), and with a significant amount of suspended matter - yellowish-green (for example, the Baltic Sea). The theoretical side of the doctrine of the C. m. was developed by V. V. Shuleikin and C. V. Raman.

Great Soviet Encyclopedia. - M.: Soviet Encyclopedia. 1969-1978

The smell of water

Smell of water – Pure water is usually odorless.

Water transparency

The transparency of water depends on the mineral substances dissolved in it and the content of mechanical impurities, organic substances and colloids:

TRANSPARENCY OF WATER - the ability of water to transmit light. Usually measured by the Secchi disk. It depends mainly on the concentration of organic and inorganic substances suspended and dissolved in water. It can sharply decrease as a result of anthropogenic pollution and eutrophication of water bodies.

Ecological encyclopedic dictionary. - Chisinau I.I. Grandpa. 1989

TRANSPARENCY OF WATER - the ability of water to transmit light rays. It depends on the thickness of the water layer passed by the rays, the presence of suspended impurities, dissolved substances, etc. In water, red and yellow rays are absorbed more strongly, violet rays penetrate deeper. According to the degree of transparency, in order of decreasing it, waters are distinguished:

• transparent;
• slightly opalescent;
• opalescent;
• slightly cloudy;
• cloudy;
• very cloudy.

Dictionary of hydrogeology and engineering geology. - M.: Gostoptekhizdat. 1961

The taste of water

The taste of water depends on the composition of the substances dissolved in it.

Dictionary of hydrogeology and engineering geology

The taste of water is a property of water that depends on the salts and gases dissolved in it. There are tables of palpable concentration of salts dissolved in water (in mg / l), for example, the following table (according to Staff).

Water temperature

Melting point of water:

MELTING POINT - The temperature at which a substance changes from solid to liquid. Melting temperature solid equals the freezing point of a liquid, for example, the melting point of ice, 0°C, is equal to the freezing point of water.

Boiling point of water : 99.974°C

Scientific and technical encyclopedic dictionary

BOILING POINT, the temperature at which a substance passes from one state (phase) to another, i.e. from liquid to vapor or gas. The boiling point increases as the external pressure increases and decreases as it decreases. It is usually measured at a standard pressure of 1 atmosphere (760 mm Hg). The boiling point of water at a standard pressure is 100 °C.

Scientific and technical encyclopedic dictionary.

Triple point of water

Triple point of water: 0.01 °C, 611.73 Pa;

Scientific and technical encyclopedic dictionary

TRIPLE POINT, temperature and pressure at which all three states of matter (solid, liquid, gaseous) can exist simultaneously. For water, the triple point is at a temperature of 273.16 K and a pressure of 610 Pa.

Scientific and technical encyclopedic dictionary.

Surface tension of water

Surface tension of water - determines the strength of the adhesion of water molecules to each other, for example, how this or that water is absorbed by the human body depends on this parameter.

Hardness of water

Marine vocabulary

WATER HARDNESS (Stiffness of Water) - a property of water, bled by the content of alkaline earth metal salts dissolved in it, ch. arr. calcium and magnesium (in the form of bicarbonate salts - bicarbonates), and salts of strong mineral acids - sulfuric and hydrochloric. Zh. V. is measured in special units, the so-called. degrees of hardness. The degree of hardness is the weight content of calcium oxide (CaO), equal to 0.01 g in 1 liter of water. Hard water is unsuitable for feeding boilers, as it contributes to the strong formation of scale on their walls, which can cause burnout of the boiler tubes. Boilers of large capacities and especially high pressures must be fed with completely purified water (condensate from steam engines and turbines, purified by filters from oil impurities, as well as distillate prepared in special evaporator apparatuses).

Samoilov K.I. Marine Dictionary. - M.-L.: State Naval Publishing House of the NKVMF USSR, 1941

Scientific and technical encyclopedic dictionary

HARDNESS OF WATER, the inability of water to form foam with soap due to salts dissolved in it, mainly calcium and magnesium.

Scale in boilers and pipes is formed due to the presence of dissolved calcium carbonate in water, which enters the water upon contact with limestone. In hot or boiling water, calcium carbonate precipitates as hard lime deposits on surfaces inside boilers. Calcium carbonate also prevents soap from lathering. The ion-exchange container (3) is filled with granules coated with sodium-containing materials. with which the water comes into contact. Sodium ions, being more active, replace calcium ions. Since sodium salts remain soluble even when boiled, scale does not form.

Scientific and technical encyclopedic dictionary.

Water structure

Water mineralization

Water mineralization :

Ecological Encyclopedic Dictionary

MINERALIZATION OF WATER - saturation of water inorganic. (mineral) substances present in it in the form of ions and colloids; the total amount of inorganic salts contained mainly in fresh water, the degree of mineralization is usually expressed in mg / l or g / l (sometimes in g / kg).

Ecological encyclopedic dictionary. - Chisinau: Main edition of the Moldavian Soviet encyclopedia. I.I. Grandpa. 1989

Viscosity of water

Viscosity of water characterizes the internal resistance of liquid particles to its movement:

Geological dictionary

The viscosity of water (liquid) is a property of a liquid that causes the appearance of a friction force during movement. It is a factor that transfers motion from layers of water moving at a high speed to layers with a lower speed. V. in. depends on the temperature and concentration of the solution. Physically, it is estimated by the coefficient. viscosity, which is included in a number of formulas for the movement of water.

Geological dictionary: in 2 volumes. - M.: Nedra. Edited by K. N. Paffengolts et al. 1978

There are two types of water viscosity:

• The dynamic viscosity of water is 0.00101 Pa s (at 20°C).

• The kinematic viscosity of water is 0.01012 cm2/s (at 20°C).

Critical point of water

The critical point of water is its state at a certain ratio of pressure and temperature, when its properties are the same in the gaseous and liquid state (gaseous and liquid phases).

Critical point of water: 374°C, 22.064 MPa.

Dielectric constant of water

Dielectric constant, in general, is a coefficient showing how much the force of interaction between two charges in a vacuum is greater than in a certain medium.

In the case of water, this figure is unusually high and for static electric fields is 81.

Heat capacity of water

Heat capacity of water - water has a surprisingly high heat capacity:

Ecological dictionary

Heat capacity is the property of substances to absorb heat. It is expressed as the amount of heat absorbed by a substance when it is heated by 1°C. The heat capacity of water is about 1 cal/g, or 4.2 J/g. The heat capacity of the soil (at 14.5-15.5°C) ranges (from sandy to peaty soils) from 0.5 to 0.6 cal (or 2.1-2.5 J) per unit volume and from 0.2 up to 0.5 cal (or 0.8-2.1 J) per unit mass (g).

Ecological dictionary. - Alma-Ata: "Science". B.A. Bykov. 1983

Scientific and technical encyclopedic dictionary

SPECIFIC HEAT CAPACITY (symbol c), the heat required to raise the temperature of 1 kg of a substance by 1K. It is measured in J / K.kg (where J is JOUL). Substances with a high specific heat capacity, such as water, require more energy to raise the temperature than substances with low specific heat.

Scientific and technical encyclopedic dictionary.

Thermal conductivity of water

The thermal conductivity of a substance refers to its ability to conduct heat from its hotter parts to its colder parts.

Heat transfer in water occurs either on molecular level, i.e., transmitted by water molecules, or due to the movement / movement of any volumes of water - turbulent thermal conductivity.

The thermal conductivity of water depends on temperature and pressure.

Water fluidity

The fluidity of substances is understood as their ability to change their shape under the influence of constant stress or constant pressure.

The fluidity of liquids is also determined by the mobility of their particles, which at rest are unable to perceive shear stresses.

Water inductance

Inductance determines the magnetic properties of closed electric current circuits. Water, with the exception of some cases, conducts electric current, and therefore has a certain inductance.

Density of water

The density of water is determined by the ratio of its mass to volume at a certain temperature. Read more in our material - WHAT IS THE DENSITY OF WATER(read →) .

Water compressibility

The compressibility of water is negligible and depends on the salinity of the water and pressure. For example, for distilled water, it is 0.0000490.

Electrical conductivity of water

The electrical conductivity of water depends largely on the amount of salts dissolved in them.

Water radioactivity

The radioactivity of water depends on the content of radon in it, the emanation of radium.

Physical and chemical properties of water

Dictionary of hydrogeology and engineering geology

PHYSICAL AND CHEMICAL PROPERTIES OF WATER — parameters that determine the physical and chemical characteristics of natural waters. These include indicators of hydrogen ion concentration (pH) and redox potential (Eh).

Dictionary of hydrogeology and engineering geology. - M.: Gostoptekhizdat. Compiled by: A. A. Makkaveev, editor O. K. Lange. 1961

Acid-base balance of water

Redox potential of water

The redox potential of water (ORP) is the ability of water to enter into biochemical reactions.

Chemical properties of water

CHEMICAL PROPERTIES OF A SUBSTANCE are properties that appear as a result of chemical reactions.

Below are the Chemical properties of water according to the textbook “Fundamentals of Chemistry. Internet textbook" by A. V. Manuylov, V. I. Rodionov.

Interaction of water with metals

When water interacts with most metals, a reaction occurs with the release of hydrogen:

• 2Na + 2H2O = H2 + 2NaOH (violently);
• 2K + 2H2O = H2 + 2KOH (violently);
• 3Fe + 4H2O = 4H2 + Fe3O4 (only when heated).

Not all, just enough active metals can participate in redox reactions of this type. Alkali and alkaline earth metals of groups I and II react most easily.

Interaction of water with non-metals

Among non-metals, for example, carbon and its hydrogen compound (methane) react with water. These substances are much less active than metals, but still able to react with water at high temperatures:

• C + H2O = H2 + CO (with strong heating);
• CH4 + 2H2O = 4H2 + CO2 (with strong heating).

Interaction of water with electric current

When exposed electric shock water decomposes into hydrogen and oxygen. It is also a redox reaction, where water is both an oxidizing agent and a reducing agent.

Interaction of water with non-metal oxides

Water reacts with many non-metal oxides and some metal oxides. These are not redox reactions, but compound reactions:

SO2 + H2O = H2SO3 (sulphurous acid)

SO3 + H2O = H2SO4 (sulfuric acid)

CO2 + H2O = H2CO3 (carbonic acid)

Interaction of water with metal oxides

Some metal oxides can also react with water. We have already seen examples of such reactions:

CaO + H2O = Ca(OH)2 (calcium hydroxide (slaked lime)

Not all metal oxides are capable of reacting with water. Some of them are practically insoluble in water and therefore do not react with water. For example: ZnO, TiO2, Cr2O3, from which, for example, water-resistant paints are prepared. Iron oxides are also insoluble in water and do not react with it.

Hydrates and crystalline hydrates

Water forms compounds, hydrates and crystalline hydrates, in which the water molecule is completely preserved.

For example:

• CuSO4 + 5H2O = CuSO4.5H2O;
• CuSO4 is a white substance (anhydrous copper sulfate);
• CuSO4.5H2O is a crystalline hydrate ( blue vitriol), blue crystals.

Other examples of hydrate formation:

• H2SO4 + H2O = H2SO4.H2O (sulfuric acid hydrate);
• NaOH + H2O = NaOH.H2O (caustic soda hydrate).

Compounds that bind water into hydrates and crystalline hydrates are used as desiccants. With their help, for example, remove water vapor from moist atmospheric air.

Biosynthesis

Water is involved in bio-synthesis as a result of which oxygen is formed:

6n CO 2 + 5n H 2 O \u003d (C 6 H 10 O 5) n + 6n O 2 (under the action of light)

We see that the properties of water are diverse and cover almost all aspects of life on Earth. As one of the scientists formulated … it is necessary to study water in a complex way, and not in the context of its individual manifestations.

In preparing the material, information was used from books - Yu. P. Rassadkin “Ordinary and Extraordinary Water”, Yu. Ya. Fialkov “Unusual Properties of Ordinary Solutions”, Textbook “Fundamentals of Chemistry. Internet textbook" by A. V. Manuylov, V. I. Rodionov and others.