Chemical reactions proceeding with sound are examples. Sound vibrations in the intensification of chemical-technological processes. Decomposition of hydrogen peroxide catalyzed by potassium iodide

Incredible Facts

The molecular material in our daily lives is so predictable that we often forget what amazing things can happen to the basic elements.

Even within our body, many amazing chemical reactions take place.

Here are some fascinating and impressive GIF-shaped chemical and physical reactions that will remind you of a chemistry course.

chemical reactions

1. "Pharaoh's snake" - the decay of mercury thiocyanate

The burning of mercury thiocyanate causes it to decompose into three other chemicals. These three chemicals in turn decompose into three more substances, which leads to the deployment of a huge "snake".

2. Burning match

The match head contains red phosphorus, sulfur and Bertolet's salt. The heat generated by the phosphorus decomposes Bertolet salt and releases oxygen in the process. Oxygen combines with sulfur to produce a short-lived flame that we use to light a candle, for example.

3. Fire + hydrogen

Hydrogen gas is lighter than air and can be ignited with a flame or spark, resulting in a spectacular explosion. That's why helium is now more commonly used than hydrogen to fill balloons.

4. Mercury + aluminum

The mercury penetrates the protective oxide layer (rust) of the aluminum, causing it to rust much faster.

Examples of chemical reactions

5. Snake venom + blood

One drop of viper venom in a petri dish of blood causes it to curl up into a thick lump of solid matter. This is what happens in our body when we are bitten by a venomous snake.

6. Iron + copper sulphate solution

The iron replaces the copper in solution, turning the copper sulfate into iron sulfate. Pure copper is collected on iron.

7. Ignition of the gas container

8. Chlorine tablet + medical alcohol in a closed bottle

The reaction leads to an increase in pressure and ends with the rupture of the container.

9. Polymerization of p-nitroaniline

On a gif, a few drops of concentrated sulfuric acid are added to half a teaspoon of p-nitroaniline or 4-nitroaniline.

10. Blood in hydrogen peroxide

An enzyme in the blood called catalase converts hydrogen peroxide into water and oxygen gas, creating a foam of oxygen bubbles.

Chemical experiments

11. Gallium in hot water

Gallium, which is mainly used in electronics, has a melting point of 29.4 degrees Celsius, which means it will melt in your hands.

12. Slow transition of beta tin to alpha modification

At cold temperatures, the beta allotrope of tin (silver, metallic) spontaneously transforms into the alpha allotrope (gray, powdery).

13. Sodium polyacrylate + water

Sodium polyacrylate, the same material used in baby diapers, acts like a sponge to absorb moisture. When mixed with water, the compound turns into a solid gel, and the water is no longer a liquid and cannot be poured out.

14. Radon 220 gas will be injected into the fog chamber

The V-shaped trail is due to two alpha particles (helium-4 nuclei) that are released when radon breaks down into polonium and then lead.

Home chemistry experiments

15. Hydrogel balls and colorful water

In this case, diffusion takes place. Hydrogel is a polymer granules that absorb water very well.

16. Acetone + Styrofoam

Styrofoam is made of Styrofoam, which, when dissolved in acetone, releases air into the foam, which makes it look like you are dissolving a large amount of material in a small amount of liquid.

17. Dry ice + dish soap

Dry ice placed in water creates a cloud, while dishwashing detergent in water holds carbon dioxide and water vapor in a bubble shape.

18. A drop of detergent added to milk with food coloring

Milk is mostly water, but it also contains vitamins, minerals, proteins, and tiny droplets of fat suspended in solution.

Dishwashing detergent loosens the chemical bonds that hold proteins and fats in solution. The fat molecules get confused as the soap molecules start rushing around to connect with the fat molecules until the solution is evenly mixed.

19. Elephant Toothpaste

Yeast and warm water are poured into a container with detergent, hydrogen peroxide and food coloring. Yeast serves as a catalyst for the release of oxygen from hydrogen peroxide, creating many bubbles. As a result, an exothermic reaction is formed, with the formation of foam and the release of heat.

Chemical experiments (video)

20. Bulb Burnout

The tungsten filament breaks, causing an electrical short circuit that causes the filament to glow.

21. Ferrofluid in a glass jar

A ferrofluid is a liquid that becomes highly magnetized in the presence of a magnetic field. It is used in hard drives and in mechanical engineering.

Another ferrofluid.

22. Iodine + aluminum

Oxidation of finely dispersed aluminum occurs in water, forming dark purple vapors.

23. Rubidium + water

Rubidium reacts very quickly with water to form rubidium hydroxide and hydrogen gas. The reaction is so fast that if carried out in a glass vessel, it could break.

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Introduction

1. The concept of sound. sound waves

1.1 Area of study of sound effects on chemical processes
1.2 Sound chemistry methods

2. Use of infrasound as a method of intensification chemical technology processes
3. The use of ultrasound as a way to intensify chemical processes
Conclusion
Introduction
The twenty-first century is the century of bio- and nanotechnologies, universal informatization, electronics, infrasound and ultrasound. Ultrasound and infrasound are a wave-like propagating oscillatory motion of the particles of the medium and are characterized by a number of distinctive features compared to the oscillations of the audible range. In the ultrasonic frequency range, it is relatively easy to obtain directional radiation; ultrasonic vibrations lend themselves well to focusing, as a result of which the intensity of ultrasonic vibrations in certain zones of influence increases. When propagating in gases, liquids and solids, sound vibrations generate unique phenomena, many of which have found practical application in various fields of science and technology, dozens of highly efficient, resource-saving sound technologies have appeared. In recent years, the use of sound vibrations has begun to play an increasingly important role in industry and scientific research. Theoretical and experimental studies in the field of ultrasonic cavitation and acoustic flows have been successfully carried out, which made it possible to develop new technological processes that occur under the action of ultrasound in the liquid phase.
At present, a new direction in chemistry is being formed - sound chemistry, which makes it possible to accelerate many chemical-technological processes and obtain new substances, along with theoretical and experimental studies in the field of sound-chemical reactions, a lot of practical work has been done. The development and application of sound technologies currently opens up new prospects in the creation of new substances and materials, in imparting new properties to known materials and media, and therefore requires an understanding of the phenomena and processes occurring under the action of ultrasound and infrasound, the possibilities of new technologies and the prospects for their application.
1. The concept of sound. sound waves

Sound is a physical phenomenon, which is the propagation of mechanical vibrations in the form of elastic waves in a solid, liquid or gaseous medium. In a narrow sense, sound refers to these vibrations, considered in connection with how they are perceived by the sense organs of animals and humans.

Like any wave, sound is characterized by amplitude and frequency spectrum. An ordinary person is able to hear sound vibrations in the frequency range from 16-20 Hz to 15-20 kHz. Sound below the human hearing range is called infrasound; higher: up to 1 GHz - by ultrasound, from 1 GHz - by hypersound. The loudness of a sound in a complex way depends on the effective sound pressure, frequency and shape of the vibrations, and the pitch of the sound depends not only on the frequency, but also on the magnitude of the sound pressure.

Sound waves in air are alternating areas of compression and rarefaction. Sound waves can serve as an example of an oscillatory process. Any fluctuation is associated with a violation of the equilibrium state of the system and is expressed in the deviation of its characteristics from equilibrium values with a subsequent return to the original value. For sound vibrations, such a characteristic is the pressure at a point in the medium, and its deviation is the sound pressure.

If you make a sharp displacement of the particles of an elastic medium in one place, for example, using a piston, then the pressure will increase in this place. Thanks to the elastic bonds of the particles, the pressure is transferred to neighboring particles, which, in turn, act on the next ones, and the area of increased pressure, as it were, moves in an elastic medium. The area of high pressure is followed by the area of low pressure, and thus, a series of alternating areas of compression and rarefaction is formed, propagating in the medium in the form of a wave. Each particle of the elastic medium in this case will oscillate.

Figure 1 - The movement of particles during the propagation of a wave a) the movement of particles of the medium during the propagation of a longitudinal wave; b) the movement of particles of the medium during the propagation of a transverse wave.

Figure 2 - Characteristics of the oscillatory process

In liquid and gaseous media, where there are no significant fluctuations in density, acoustic waves are longitudinal in nature, that is, the direction of particle oscillation coincides with the direction of wave movement. In solids, in addition to longitudinal deformations, elastic shear deformations also arise, which cause the excitation of transverse (shear) waves; in this case, the particles oscillate perpendicular to the direction of wave propagation. The velocity of propagation of longitudinal waves is much greater than the velocity of propagation of shear waves.

1.1 Area of study of sound effects on chemical processes

The branch of chemistry that studies the interaction of powerful acoustic waves and the resulting chemical and physicochemical effects is called sonochemistry (sonochemistry). Sonochemistry investigates the kinetics and mechanism of sonochemical reactions occurring in the volume of a sound field. The field of sound chemistry also includes some physical and chemical processes in a sound field: sonoluminescence, dispersion of a substance under the action of sound, emulsification and other colloidal chemical processes. Sonoluminescence is the phenomenon of the appearance of a flash of light during the collapse of cavitation bubbles generated in a liquid by a powerful ultrasonic wave. A typical experience for observing sonoluminescence is as follows: a resonator is placed in a container of water and a standing spherical ultrasonic wave is created in it. With sufficient ultrasound power, a bright point source of bluish light appears in the very center of the tank - the sound turns into light. Sonochemistry pays the main attention to the study of chemical reactions that occur under the action of acoustic vibrations - sonochemical reactions.

As a rule, sound-chemical processes are studied in the ultrasonic range (from 20 kHz to several MHz). Sound vibrations in the kilohertz range and the infrasonic range are studied much less frequently.

Sound chemistry investigates the processes of cavitation. Cavitation (from Latin cavita - emptiness) is the process of vaporization and subsequent condensation of vapor bubbles in a liquid stream, accompanied by noise and hydraulic shocks, the formation of cavities in the liquid (cavitation bubbles, or caverns) filled with vapor of the liquid itself in which it occurs. Cavitation occurs as a result of a local decrease in pressure in the liquid, which can occur either with an increase in its speed (hydrodynamic cavitation), or with the passage of an acoustic wave of high intensity during the rarefaction half-cycle (acoustic cavitation), there are other reasons for the effect. Moving with the flow to an area with a higher pressure or during a half-cycle of compression, the cavitation bubble collapses, while emitting a shock wave.

1.2 Sound chemistry methods

The following methods are used to study sound-chemical reactions: the inverse piezoelectric effect and the magnetostriction effect for generating high-frequency sound vibrations in a liquid, analytical chemistry for studying the products of sound-chemical reactions, the inverse piezoelectric effect - the occurrence of mechanical deformations under the action of an electric field (used in acoustic emitters, in systems mechanical movements - activators).

Magnetostrimction is a phenomenon consisting in the fact that when the state of magnetization of a body changes, its volume and linear dimensions change (they are used to generate ultrasound and hypersound).

Infrasound is sound waves that have a frequency below that perceived by the human ear. Since the human ear is usually able to hear sounds in the frequency range of 16-20 "000 Hz, 16 Hz is usually taken as the upper limit of the infrasound frequency range. The lower limit of the infrasound range is conditionally defined as 0.001 Hz.

Infrasound has a number of features associated with the low frequency of oscillations of an elastic medium: it has much larger oscillation amplitudes; spreads much further in the air, since its absorption in the atmosphere is negligible; exhibits the phenomenon of diffraction, as a result of which it easily penetrates into rooms and goes around obstacles that delay audible sounds; causes large objects to vibrate due to resonance.

wave ultrasound chemical cavitation

2. Using infrasound as a way to intensify chemical-technological processes

The physical impact on chemical reactions in this case is carried out in infrasonic devices,- devices in which low-frequency acoustic vibrations are used to intensify technological processes in liquid media (actually infrasonic with a frequency of up to 20 Hz, sound with a frequency of up to 100 Hz). Oscillations are created directly in the processed medium with the help of flexible emitters of various configurations and shapes or rigid metal pistons connected to the walls of technological containers through elastic elements (eg, rubber). This makes it possible to unload the walls of the infrasonic apparatus from vibrations of the source, significantly reduces their vibration and the noise level in industrial premises. In infrasonic devices, oscillations with large amplitudes (from units to tens of mm) are excited.

However, the low absorption of infrasound by the working medium and the possibility of its matching with the emitter of oscillations (selection of appropriate source parameters) and the size of the apparatus (for processing given volumes of liquid) make it possible to extend the nonlinear wave effects arising under the influence of infrasound to large technological volumes. Due to this, infrasonic devices are fundamentally different from ultrasonic ones, in which liquids are processed in a small volume.

In infrasonic devices, the following physical effects are realized (one or more simultaneously): cavitation, high-amplitude alternating and radiation (sound radiation) pressures, alternating fluid flows, acoustic currents (sonic wind), degassing of the fluid and the formation of a multitude of gas bubbles and their equilibrium layers in it , phase shift of oscillations between suspended particles and liquid. These effects significantly accelerate redox, electrochemical and other reactions, intensify by 2-4 times the industrial processes of mixing, filtering, dissolving and dispersing solid materials in liquids, separating, classifying and dehydrating suspensions, as well as cleaning parts and mechanisms, etc. .

The use of infrasound allows several times to reduce the specific energy and metal consumption and overall dimensions of the apparatus, as well as process liquids directly in the stream when transporting them through pipelines, which eliminates the installation of mixers and other devices.

Figure 3 - Infrasonic apparatus for mixing suspensions: 1 - membrane vibration emitter; 2 - compressed air modulator; 3 - boot device; 4 - compressor

One of the most common applications of infrasound is the mixing of suspensions by means of, for example, tube infrasound apparatus. Such a machine consists of one or more serially connected hydropneumatic emitters and a loading device.

3. The use of ultrasound in the intensification of chemical processes

Ultrasound microns - sound waves having a frequency higher than the perceived by the human ear, usually, ultrasound is understood to mean frequencies above 20,000 Hertz. High frequency vibrations used in industry are usually created using piezoceramic transducers. In cases where the power of ultrasonic vibrations is of primary importance, mechanical sources of ultrasound are used.

The impact of ultrasound on chemical and physico-chemical processes occurring in a liquid includes: the initiation of some chemical reactions, changing the rate and sometimes the direction of reactions, the appearance of a glow in the liquid (sonoluminescence), the creation of shock waves in the liquid, the emulsification of immiscible liquids and coalescence particles inside the moving medium or on the surface of the body) emulsions, dispersion (fine grinding of solids or liquids) of solids and coagulation (combining small dispersed particles into larger aggregates) of solid particles in liquids, degassing of liquids, etc. For the implementation of technological processes, ultrasonic devices are used.

The influence of ultrasound on various processes is associated with cavitation (the formation in a liquid during the passage of an acoustic wave of cavities (cavitation bubbles) filled with gas, steam or a mixture thereof).

Chemical reactions that occur in a liquid under the action of ultrasound (sound-chemical reactions) can be divided into: a) redox reactions occurring in aqueous solutions between dissolved substances and decomposition products of water molecules inside the cavitation bubble (H, OH,), for example :

b) Reactions between dissolved gases and substances with high vapor pressure inside the cavitation bubble:

c) Chain reactions initiated not by radical products of water decomposition, but by some other substance dissociating in a cavitation bubble, for example, isomerization of maleic acid to fumaric acid under the action of Br, which is formed as a result of sonochemical dissociation.

d) Reactions involving macromolecules. For these reactions, not only cavitation and associated shock waves and cumulative jets are important, but also mechanical forces that split molecules. The resulting macroradicals in the presence of the monomer are capable of initiating polymerization.

e) Initiation of an explosion in liquid and solid explosives.

f) Reactions in liquid non-aqueous systems, for example, pyrolysis and oxidation of hydrocarbons, oxidation of aldehydes and alcohols, alkylation of aromatic compounds, etc.

The main energy characteristic of sonochemical reactions is the energy yield, which is expressed by the number of product molecules formed at the cost of 100 eV of absorbed energy. The energy yield of the products of redox reactions usually does not exceed a few units, and for chain reactions it reaches several thousand.

Under the action of ultrasound in many reactions, it is possible to increase the rate by several times (for example, in the reactions of hydrogenation, isomerization, oxidation, etc.), sometimes the yield also increases at the same time.

It is important to take into account the impact of ultrasound in the development and implementation of various technological processes (for example, when exposed to water, in which air is dissolved, nitrogen oxides and are formed), in order to understand the processes that accompany the absorption of sound in media.

Conclusion

At present, sound vibrations are widely used in industry, being a promising technological factor that makes it possible, if necessary, to sharply intensify production processes.

The use of powerful ultrasound in technological processes for the production and processing of materials and substances allows:

Reduce the cost of a process or product,

Receive new products or improve the quality of existing ones,

Intensify traditional technological processes or stimulate the implementation of new ones,

Contribute to the improvement of the environmental situation by reducing the aggressiveness of process fluids.

However, it should be noted that ultrasound has an extremely adverse effect on living organisms. In order to reduce such impacts, ultrasonic installations are recommended to be placed in special rooms, using remote control systems for technological processes. The automation of these installations has a great effect.

A more economical way to protect against the effects of ultrasound is to use soundproof casings that close ultrasonic installations, or screens located in the path of ultrasound. These screens are made of sheet steel or duralumin, plastic or special rubber.

List of sources used

1. Margulis M.A. Fundamentals of sound chemistry (chemical reactions in acoustic fields); textbook allowance for chem. and chemical technologist. Specialties of universities / M.A. Margulis. M.: Higher school, 1984. 272 p.

2. Suslik K.S. Ultrasound. Its chemical, physical and biological effects. Ed.: VCH, N. Y., 336 p.

3. Kardashev G.A. Physical methods of intensification of chemical technology processes. Moscow: Chemistry, 1990, 208 p.

5. Luminescence

6. Ultrasound

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2. Oxidation reaction of luminol and potassium hexacyanoferrate(III)

Here is an example of chemiluminescence: during the transformation of luminol, a glow is clearly visible to the human eye. Red blood salt acts here as a catalyst - by the way, hemoglobin can play the same role, as a result of which the described reaction is widely used in criminology to detect traces of blood.

Source: Professor Nicolas Science Show

3. Balloon filled with mercury (reaction when hitting the floor)

Mercury is the only metal that remains liquid under normal conditions, allowing it to be poured into a balloon. However, mercury is so heavy that even a ball dropped from a small height will tear it to shreds.

Source: Long time no kids

4. Decomposition of hydrogen peroxide catalyzed by potassium iodide

In the absence of impurities, an aqueous solution of hydrogen peroxide is quite stable, but as soon as potassium iodide is added to it, the decomposition of these molecules will immediately begin. It is accompanied by the release of molecular oxygen, which perfectly contributes to the formation of various foams.

Source: fishki.net

5. Iron + copper sulfate

One of the first reactions studied in the Russian chemistry course: as a result of substitution, the more active metal (iron) dissolves and goes into solution, while the less active metal (copper) precipitates in the form of colored flakes. As you might guess, the animation is greatly accelerated in time.

Source: Trinixy

6. Hydrogen peroxide and potassium iodide

Another example of the decomposition reaction of hydrogen peroxide (aka peroxide) in the presence of a catalyst. Pay attention to the bottle of detergent standing on the table: it is she who helps to appear the soap sausage falling on the table.

Source: Trinixy

7. Lithium combustion

Lithium is one of the alkali metals, rightfully considered the most active among all other metals. It does not burn as intensely as its counterparts sodium and potassium, but it is easy to see that this process is still very fast.

Source: Trinixy

8. Dehydration of sugar in sulfuric acid

A very simple and very effective reaction: sulfuric acid takes water away from sucrose molecules, turning them into atomic carbon (simply into coal). The gaseous water released at the same time foams the coal, thanks to which we see a menacing black column.

Source: fishki.net

9. Quartz glass

Unlike standard window glass, quartz is more resistant to high temperatures: it will not "flow" on a conventional gas burner. That is why quartz tubes are soldered on oxygen burners, which provide a higher flame temperature.

Source: Global Research

10. Fluorescein

In an aqueous solution, under the action of ultraviolet radiation, the green dye fluorescein emits light in the visible range - this phenomenon is called fluorescence.

Source: Thoisoi

11. Zipper in the top hat

The reaction between carbon sulfide and nitric oxide (I) is not only accompanied by the brightest white flash, reminiscent of ball lightning, but is also characterized by a funny sound, thanks to which it got its popular name - "barking dog." That sometimes they try to pass off this substance as a precious metal .

The final result of explosive transformation reactions is usually expressed by an equation relating the chemical formula of the initial explosive or its composition (in the case of an explosive mixture) with the composition of the final explosion products.

Knowledge of the equation of chemical transformation during an explosion is essential in two respects. On the one hand, this equation can be used to calculate the heat and volume of the gaseous products of an explosion, and, consequently, the temperature, pressure, and other parameters of the explosion. On the other hand, the composition of the explosion products is of particular importance when it comes to explosives intended for blasting in underground workings (hence the calculation of mine ventilation so that the amount of carbon monoxide and nitrogen oxides does not exceed a certain volume).

However, during an explosion, chemical equilibrium is not always established. In those numerous cases when the calculation does not allow one to reliably establish the final equilibrium of the explosive transformation, one turns to experiment. But the experimental determination of the composition of the products at the time of the explosion also encounters serious difficulties, since the products of the explosion at high temperatures may contain atoms and free radicals (active particles), which cannot be detected after cooling.

Organic explosives, as a rule, consist of carbon, hydrogen, oxygen and nitrogen. Therefore, the explosion products may contain the following gaseous and solid substances: CO 2, H 2 O, N 2, CO, O 2, H 2, CH 4 and other hydrocarbons: NH 3, C 2 N 2, HCN, NO, N 2 O, C. If the composition of explosives includes sulfur or chlorine, then the products of the explosion may contain SO 2 , H 2 S, HCl and Cl 2, respectively. In the case of the content of metals in the composition of explosives, for example, aluminum or some salts (for example, ammonium nitrate NH 4 NO 3, barium nitrate Ba (NO 3) 2; chlorates - barium chlorate Ba (ClO 3) 2, potassium chlorate KClO 3 ; perchlorates - ammonium NHClO 4, etc.) in the composition of the explosion products there are oxides, for example Al 2 O 3, carbonates, for example, barium carbonate BaCO 3, potassium carbonate K 2 CO 3, bicarbonates (KHCO 3), cyanides (KCN), sulfates (BaSO 4, K 2 SO 4), sulfides (NS, K 2 S), sulfites (K 2 S 2 O 3), chlorides (AlC l 3 , BaCl 2 , KCl) and other compounds.

The presence and amount of certain explosion products primarily depend on the oxygen balance of the explosive composition.

The oxygen balance characterizes the ratio between the content of combustible elements and oxygen in the explosive.

The oxygen balance is usually calculated as the difference between the weight amount of oxygen contained in the explosive and the amount of oxygen required for the complete oxidation of the combustible elements included in its composition. The calculation is carried out for 100 g of explosive, in accordance with which the oxygen balance is expressed as a percentage. The provision of the composition with oxygen is characterized by the oxygen balance (KB) or the oxygen coefficient a to, which in relative terms express the excess or lack of oxygen for the complete oxidation of combustible elements to higher oxides, for example, CO 2 and H 2 O.

If an explosive contains just as much oxygen as is necessary for the complete oxidation of its constituent combustible elements, then its oxygen balance is equal to zero. If the excess - KB is positive, with a lack of oxygen - KB is negative. The balance of explosives in terms of oxygen corresponds to CB - 0; a to = 1.

If an explosive contains carbon, hydrogen, nitrogen, and oxygen and is described by the equation C a H b N c O d , then the values of the oxygen balance and oxygen coefficient can be determined by the formulas

(2)

where a, b, c, and d are the number of C, H, N, and O atoms, respectively, in the chemical formula of the explosive; 12, 1, 14, 16 are the atomic masses of carbon, hydrogen, nitrogen and oxygen rounded to the nearest integer; the denominator of the fraction in equation (1) determines the molecular weight of the explosive: M = 12a + b + 14c + 16d.

From the point of view of the safety of production and operation (storage, transportation, use) of explosives, most of their formulations have a negative oxygen balance.

According to the oxygen balance, all explosives are divided into the following three groups:

I. Explosives with a positive oxygen balance: carbon is oxidized to CO 2 , hydrogen to H 2 O, nitrogen and excess oxygen are released in elemental form.

II. Explosives with a negative oxygen balance, when oxygen is not enough for the complete oxidation of components to higher oxides and carbon is partially oxidized to CO (but all explosives turn into gases).

III. An explosive with a negative oxygen balance, but oxygen is not enough to convert all combustible components into gases (there is elemental carbon in the explosion products).

4.4.1. Calculation of the composition of products of explosive decomposition of explosives

with a positive oxygen balance (I group of explosives)

When compiling the equations for explosion reactions, explosives with a positive oxygen balance are guided by the following provisions: carbon is oxidized to carbon dioxide CO 2, hydrogen to water H 2 O, nitrogen and excess oxygen are released in elemental form (N 2, O 2).

For instance.

1. Write a reaction equation (determine the composition of the explosion products) of the explosive decomposition of an individual explosive.

Nitroglycerin: C 3 H 5 (ONO 2) 3, M = 227.

We determine the value of the oxygen balance for nitroglycerin:

KB > 0, we write the reaction equation:

C 3 H 5 (ONO 2) 3 \u003d 3CO 2 + 2.5H 2 O + 0.25O 2 + 1.5N 2.

In addition to the main reaction, dissociation reactions proceed:

2CO 2 2CO + O 2;

O 2 + N 2 2NO;

2H 2 O 2H 2 + O 2;

H 2 O + CO CO 2 + H 2.

But since KB \u003d 3.5 (much more than zero) - the reactions are shifted towards the formation of CO 2, H 2 O, N 2, therefore, the proportion of CO, H 2 and NO gases in the explosive decomposition products is insignificant and they can be neglected.

2. Compose an equation for the reaction of the explosive decomposition of mixed explosives: ammonal, consisting of 80% ammonium nitrate NH 4 NO 3 (M = 80), 15% TNT C 7 H 5 N 3 O 6 (M = 227) and 5% aluminum Al ( a.m. M = 27).

The calculation of the oxygen balance and the coefficient α to mixed explosives is carried out as follows: the amount of each of the chemical elements contained in 1 kg of the mixture is calculated and expressed in moles. Then they make up a conditional chemical formula for 1 kg of a mixed explosive, similar in appearance to the chemical formula for an individual explosive, and then the calculation is carried out similarly to the above example.

If the mixed explosive contains aluminum, then the equations for determining the values of CB and α to have the following form:

where e is the number of aluminum atoms in the conditional formula.

Solution.

1. We calculate the elemental composition of 1 kg of ammonal and write down its conditional chemical formula

2. Write down the reaction equation for the decomposition of ammonal:

C 4.6 H 43.3 N 20 O 34 Al 1.85 \u003d 4.6CO 2 + 21.65H 2 O + 0.925Al 2 O 3 + 10N 2 + 0.2O 2.

4.4.2. Calculation of the composition of products of explosive decomposition of explosives

with negative oxygen balance (II group BB)

As noted earlier, when compiling the equations for the reactions of explosive decomposition of explosives of the second group, the following features must be taken into account: hydrogen is oxidized to H 2 O, carbon is oxidized to CO, the remaining oxygen oxidizes part of CO to CO 2 and nitrogen is released in the form of N 2.

Example: Compose an equation for the reaction of the explosive decomposition of pentaerythritol tetranitrate (PETN) C (CH 2 ONO 2) 4 Mthena \u003d 316. The oxygen balance is equal to -10.1%.

It can be seen from the chemical formula of the heating element that oxygen is not enough until hydrogen and carbon are completely oxidized (for 8 hydrogens, 4 oxygen atoms are needed to turn into H 2 O \u003d 4H 2 O) (for 5 carbon atoms, 10 oxygen atoms are needed to turn in CO 2 \u003d 5CO 2) total 4 + 10 \u003d 14 at. oxygen, and there are only 12 atoms.

1. We compose the reaction equation for the decomposition of the heating element:

C (CH 2 ONO 2) 4 \u003d 5CO + 4H 2 O + 1.5O 2 + 2N 2 \u003d 4H 2 O + 2CO + 3CO 2 + 2N 2.

To determine the value of the CO and CO 2 coefficients:

5CO + 1.5O 2 \u003d xCO + yCO 2,

x + y \u003d n - the sum of carbon atoms,

x + 2y \u003d m - the sum of oxygen atoms,

X + y \u003d 5 x \u003d 5 - y

x + 2y = 8 or x = 8 - 2y

or 5 - y \u003d 8 - 2y; y \u003d 8 - 5 \u003d 3; x \u003d 5 - 3 \u003d 2.

That. coefficient at CO x = 2; at CO 2 y \u003d 3, i.e.

5CO + 1.5 O 2 \u003d 2CO + 3CO 2.

Secondary reactions (dissociations):

Water vapor: H 2 O + CO CO 2 + H 2;

2H 2 O 2H 2 + O 2;

Dissociation: 2CO 2 2CO + O 2;

2. To estimate the error, we calculate the composition of the products of the explosive decomposition reaction, taking into account the most significant of the secondary reactions - the reaction of water vapor (H 2 O + CO CO 2 + H 2).

The reaction equation for the explosive decomposition of PETN can be represented as:

C (CH 2 ONO 2) 4 \u003d uH 2 O + xCO + yCO 2 + zH 2 + 2N 2.

The temperature of the explosive spill of the heating element is approximately 4000 0 K.

Accordingly, the equilibrium constant of water vapor:

We write down and solve the system of equations:

x + y = 5 (see above) is the number of carbon atoms;

2z + 2у = 8 is the number of hydrogen atoms;

x + 2y + u = 12 is the number of oxygen atoms.

The transformation of the system of equations is reduced to obtaining a quadratic equation:

7.15y 2 - 12.45y - 35 = 0.

(An equation of the type ay 2 + wy + c = 0).

Its solution looks like:

y = 3.248, then x = 1.752; z = 0.242; u = 3.758.

Thus, the reaction equation takes the form:

C (CH 2 ONO 2) 4 \u003d 1.752CO + 3.248CO 2 + 3.758H 2 O + 0.242H 2 + 2N 2.

It can be seen from the resulting equation that the error in determining the composition and amount of explosive decomposition products by an approximate method is insignificant.

4.4.3. Drawing up equations for the reactions of explosive decomposition of explosives

with negative CB (group III)

When writing the equations for the reaction of explosive decomposition for the third group of explosives, it is necessary to adhere to the following sequence:

1. determine its KB by the chemical formula of explosives;

2. oxidize hydrogen to H 2 O;

3. oxidize carbon with oxygen residues to CO;

4. write the rest of the reaction products, in particular C, N, etc.;

5. Check odds.

Example : Write an equation for the explosive decomposition of trinitrotoluene (trotyl, tol) C 6 H 2 (NO 2) 3 CH 3 .

Molar mass M = 227; KB = -74.0%.

Solution: From the chemical formula, we see that oxygen is not enough for the oxidation of carbon and hydrogen: for the complete oxidation of hydrogen, 2.5 oxygen atoms are needed, for incomplete oxidation of carbon, 7 atoms (only 9.5 compared to the existing 6 atoms). In this case, the reaction equation for the decomposition of TNT has the form:

C 6 H 2 (NO 2) 3 CH 3 \u003d 2.5H 2 O + 3.5CO + 3.5 C + 1.5N 2.

secondary reactions:

H 2 O + CO CO 2 + H 2;