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Table of contents

Introduction 3

Theoretical part 5

History of opening indicators 5

Classification of school indicators and methods of their use 6

pH value 6

Experimental part 8

Sociological survey 8

Preparation of an indicator from natural material 9

Laboratory study “Measurement of pH levels in cleansers”…………………………………………………………………………………10

Conclusion 14

List of sources used 15

Introduction

In the modern world it is almost impossible to do without cosmetics. Soaps, shampoos, scrubs, lotions, tonics, creams... It's hard for us to imagine our life without this. Cosmetics have accompanied our lives since birth. There are a lot of products from different manufacturers on store shelves: “UNILEVER”, “Beiersdorf”, “Oriflame”, etc. Manufacturers - both domestic and foreign - vying with each other to offer new products, praising their wonderful properties. Cosmetics can be used from an early age (for example, “Jonson's Baby”, “Bubchen” are intended for children). The main purpose of modern cosmetics is to give people the opportunity to remain beautiful all their lives. Every morning we wash ourselves with special cosmetics, while our grandmothers washed with spring water. Otherwise, it is impossible: we live in completely different environmental conditions. Water will not dissolve the sweat and fat secretions of the skin, mixed with dust and city exhaust. Moreover, our tap water contains bleach. And ordinary soap, which is alkali, will dry out the skin It is necessary to use special washing products that contain softer substances compared to soap, and in addition to cleansing, care for the skin, taking into account its type.

If you buy unsuitable clothes or shoes, you can easily return them back to the store. Unfortunately, this is not possible with cosmetics. To avoid being upset to tears because of an unsuccessful product, you need to choose cosmetics more carefully. One of the important guidelines when choosing a cosmetic product is the pH value.

Having learned to determine pH, we will be able to make cosmetics at home using only environmentally friendly natural ingredients. To determine pH, special indicators or test strips are required. 0000000 Target: making an indicator at home; determining the quality of various cleansers using an indicator.

Research objectives:

Conduct an analysis of scientific literature on this issue;

Find out the history of the appearance of indicators;

Explore ways to form indicators;

Prepare indicators from natural materials at home;

Conduct analysis of cosmetic products, make video recordings of research

Hypothesis: Let's assume that the indicators can be prepared at home.

Object of study: indicators

Subject of study: composition of indicators

Methods: analysis of scientific literature, observation, laboratory experiment, experience, questioning, analysis of the results obtained.

Theoretical part

History of indicator discovery

Indicators- means “pointers”. These are substances that change color depending on whether they are in an acidic, alkaline or neutral environment. The most common indicators are litmus, phenolphthalein, and methyl orange.

The very first acid-base indicator, litmus, appeared. Litmus is an aqueous infusion of litmus lichen that grows on rocks in Scotland.

Indicators were first discovered in the 17th century by the English physicist and chemist Robert Boyle. Boyle conducted various experiments. One day, when he was conducting another study, a gardener came in. He brought violets. Boyle loved flowers, but he needed to conduct an experiment. Boyle left the flowers on the table. When the scientist finished his experiment, he accidentally looked at the flowers, they were smoking. To save the flowers, he put them in a glass of water. And - what miracles - the violets, their dark purple petals, turned red. Boyle became interested and conducted experiments with solutions, each time adding violets and observing what happened to the flowers. In some glasses, the flowers immediately began to turn red. The scientist realized that the color of violets depends on what solution is in the glass and what substances are contained in the solution. The best results were obtained from experiments with litmus lichen. Boyle dipped ordinary paper strips into an infusion of litmus lichen. I waited until they were soaked in the infusion, and then dried them. Robert Boyle called these tricky pieces of paper indicators, which translated from Latin means “pointer”, since they point to the solution environment. It was the indicators that helped the scientist discover a new acid - phosphoric acid, which he obtained by burning phosphorus and dissolving the resulting white product in water.

If there are no real chemical indicators, you can successfully use home, wild and garden flowers and even the juice of many berries - cherries, chokeberries, currants - to determine the acidity of the environment. Pink, crimson or red geranium flowers, peony or colored pea petals will turn blue when placed in an alkaline solution. Cherry and currant juice will also turn blue in an alkaline environment. On the contrary, in acid the same “reagents” will take on a pink-red color.

Plant acid-base indicators here are coloring substances - anthocyanins. It is anthocyanins that give various shades of pink, red, blue and purple to many flowers and fruits.

The beet dye betaine or betanidin becomes discolored in an alkaline environment, and turns red in an acidic environment. That's why borscht with sauerkraut has such an appetizing color.

Classification of school indicators and methods of their use.

Indicators have different classifications . Some of the most common are acid-base indicators, which change color depending on the acidity of the solution. Nowadays, several hundred artificially synthesized acid-base indicators are known, some of them can be found in a school chemistry laboratory.

Phenolphthalein (sold in a pharmacy under the name "purgen") - white or white with a slightly yellowish tint, finely crystalline powder. Soluble in 95% alcohol, practically insoluble in water. Colorless phenolphthalein is colorless in acidic and neutral environments, but turns crimson in an alkaline environment. Therefore, phenolphthalein is used to determine the alkaline environment.

Methyl orange - orange crystalline powder. Moderately soluble in water, easily soluble in hot water, practically insoluble in organic solvents. The color of the solution changes from red to yellow.

Lakmoid (litmus) - black powder. Soluble in water, 95% alcohol, acetone, glacial acetic acid. The color of the solution changes from red to blue.

Indicators are usually used by adding a few drops of an aqueous or alcoholic solution, or a little powder, to the solution being tested.

Another method of application is to use strips of paper soaked in an indicator solution or indicator mixture and dried at room temperature. Such strips are produced in a wide variety of options - with or without a color scale applied to them - a color standard.

pH value

The universal paper indicator has a scale for determining the medium (pH).

Hydrogen index, pH - a value characterizing the concentration of hydrogen ions in solutions. This concept was introduced in 1909 by the Danish chemist Sørensen. The indicator is called pH, after the first letters of Latin words potentia hydrogeni- the power of hydrogen, or pondus hydrogenii- weight of hydrogen. Aqueous solutions can have a pH value in the range of 0-14. In pure water and neutral solutions pH=7, in acidic solutions pH7. pH values ​​are measured using acid-base indicators.

Table 1. - Indicator color in various environments.

• PROJECT HYPOTHESIS

Familiarize yourself with the information literature, conduct an analysis, draw conclusions

• Familiarize yourself with the information literature, conduct an analysis, draw conclusions
• Conduct practical studies of the influence of reaction conditions on the oxidative – reduction properties of substances
• Find out the meaning of one of these substances in everyday life from the point of view of ODD

• Goal: IDENTIFYING A SUBSTANCE THAT CAN CHANGE COLOR DEPENDING ON THE SITUATION, studying its properties and applications

PROGRESS OF THE RESEARCH

• WE HAVE FOUND INFORMATION SOURCES AND LEARNED WHAT SUBSTANCES CAN CHANGE COLOR
• ANALYZED:
• REASONS FOR COLOR CHANGE
• DURING THE EXPERIMENT, THE INFLUENCE OF THE ENVIRONMENT ON THE COLOR OF KMnO4 WAS DETERMINED
• WE FOUND OUT THE IMPORTANCE OF POTASSIUM PERMANGANATE IN EVERYDAY LIFE AND ITS EFFECT ON PLANTS.

RESEARCH RESULTS

• Chemical chameleons are a number of substances that can change their color during chemical reactions.

• These include both organic and inorganic substances.

• The reasons for the color of substances depend on a number of factors

• The molecule is painted

• free electrons

• odd number of electrons in a molecule

• chemical bond strength

• nascent chemical bond

• molecule color
• depends on the structure

What reactions change the color of substances?

• The substances themselves do not change color.
• A change in color is a sign of a chemical reaction,
• more often ODD

• Potassium permanganate (lat. Kalii permanganas)
• - potassium salt of permanganic acid

• The discoverer was the Swedish chemist and pharmacist Karl-Wilhelm Scheele.
• fused “black magnesia” - the mineral pyrolusite (natural manganese dioxide), with potash - potassium carbonate and nitrate - potassium nitrate. This produced potassium permanganate, potassium nitrite and carbon dioxide:
• 2MnO2 + 3KNO3 + K2CO3 = 2KMnO4 + 3KNO2 + CO2

• MARGANSOVKA
• (KMnO4).

PROPERTIES OF POTASSIUM PERMANGANATE

• Dark purple crystals.
• Does not form crystalline hydrates.
• Solubility in water is moderate.
• Hydrolyzes
• Slowly decomposes in solution.
• Solutions are colored

PRACTICAL STUDY

• OXIDIZER
• in solution and during sintering.

• MANganese is

• DECOMPOSES

• EXPLOSIVE

• GIVES AN ALKALINE REACTION TO THE ENVIRONMENT

• changes
• coloring
• KМnO4

• Coloring
• depends
• from Wednesday
• solution

• neutral

• alkaline

• sour

• brown color

• green color

• colorless

• solution medium

• permanganate color

• The influence of the reaction of the environment on
• redox process

• Potassium permanganate forms various reduction products in different environmental reactions

APPLICATION

• KMnO4 is used as an oxidizing agent

MANganese in everyday life

• antioxidant

• APPLICATION

• BY USING MANganese IN EVERYDAY, WE CARRY OUT OVR!

• OVR - PROCESS

• antiseptic

• has an emetic effect

• "cauterization" and "drying" of the skin and mucous membranes

• astringent action

CAUTION WHEN WORKING WITH MANganese

• chemical burn
• poisoning
• Solid potassium permanganate and its strong
• solutions can be dangerous.
• Therefore, it should be stored in places inaccessible to children and handled with care.

• For a week, the soil and the diseased plant were watered with a weak solution. The white coating on the ground disappeared, the pests died. Potassium permanganate has disinfecting and antiseptic properties

• When watered once every two weeks with a weak solution, the appearance of the plants improved. Potassium permanganate contains elements that promote plant growth - manganese and potassium.

• By constantly watering the plants with a weak solution, they found that plants in alkaline soils reacted positively, while those in acidic soils reacted negatively. Potassium permanganate solution has an alkaline environment

• Treatment with a concentrated solution causes burns and even death of the plant.

results

• PROJECT HYPOTHESIS

• substances "Chameleons" exist

• CONCLUSION:
• THE SUBSTANCES THEMSELVES CHANGE COLOR
• CAN NOT.
• HYPOTHESIS NOT CONFIRMED

•  1C Tutor. Chemistry. CD – disk.
•  Big encyclopedia. Cyril and Methodius, 2005 CD.
• Kuzmenko N.E., Eremin V.V., Popkov V.A. The beginning of chemistry. Modern course for applicants to universities.
• In 2 volumes - M. 1997. BDE Biology, M. Bustard, 2004
•  Ecology. Educational encyclopedia, M. “Bustard”
•  Stepin B.D., Alikberova L.Yu. A book on chemistry for home reading. – M., Chemistry, 1994.
•  Shulpin G.B. This is fascinating chemistry. – M.; Chemistry, 1984.

• INFORMATION SOURCES

• orange dark black-green
• purple black-gray

• It is known that double and single bonds can change places with each other relatively easily. But each interatomic bond is a pair of electrons shared by the atoms they bond. So it turns out that in the conjugation section, bonding electrons can move quite freely within such a section. Such freedom entails important optical consequences.

• Another interesting fact: compounds with an odd number of electrons in the molecule are more often colored than compounds with an even number of electrons. Let's say the radical C(C6H5)3 is colored intense brown-violet, while C(C6H5)4 is colorless. Nitrogen dioxide NO2 with an odd number of electrons in the molecule is brownish-brown, and when it dimerizes, the colorless compound N2O4 is obtained (doubling the number of electrons becomes even). The reason here is that in systems with an odd number of electrons, one of them is unpaired and is able to move relatively freely throughout the entire molecule. And, as mentioned earlier, this can cause staining.

• a compound composed of almost colorless constituent parts,
• turns out to be colored. Thus, the Fe3+ ion is colorless, the Fe(CN)64 - ion, which is part of the yellow blood salt, is slightly yellow. But Fe43, obtained by merging solutions containing these ions, has an intense blue color.
• The reason for the appearance of color should be sought in the fact that a compound with stronger chemical bonds is formed here (not with ionic, but with covalent); the degree of mutual sharing of electrons becomes so significant that there is a strong shift in the absorption maximum to the visible region of the spectrum and an increase in the absorption intensity.

• Iodine solvates in water are brown-red in color, and in carbon tetrachloride they are purple

• silica gel impregnated with cobalt chloride is colored blue in dry air and pink in humid air. The thing is that with excess moisture, molecules of blue cobalt chloride CoCl2 form a complex compound with water molecules - crystal hydrate CoCl2 6H2O, which has a dark pink color.

• It is reduced to manganese compounds of varying degrees of oxidation.
• in an acidic environment: 2KMnO4+ 5K2SO3 + 3H2SO4 =
• 6K2SO4+ 2MnSO4+ 3H2O
• in neutral environment: 2 KMnO4+ 3K2SO3 + H2O =3K2SO4 + 2 MnO2+2KOH
• in an alkaline environment: 2 KMnO4+ K2SO3 + KOH=
• K2SO4 + 2 K2MnO4+ H2O,
• KMnO4 + K2SO3 + KOH =K2SO4 + K2MnO4 + H2O (in cold)

• DECOMPOSES with oxygen release
• 2KMnO4 →(t) K2MnO4 + MnO2+ O2

• EXPLOSIVE
• 2KMnO4 + 2H2SO4 → 2KHSO4 + Mn2O7 + H2O,

• Reacts with typical reducing agents
• (ethanol, hydrogen, etc.).

• It is necessary to add a KMnO4 solution to the water prepared for bathing, but under no circumstances should you add potassium permanganate crystals - otherwise a chemical burn is possible.

• In case of poisoning with a concentrated solution of this substance, a burn occurs in the mouth, esophagus and stomach (rinse the stomach with warm water with the addition of activated carbon)
• You can also use a solution containing half a glass of a weak solution of hydrogen peroxide and one glass of table vinegar in two liters of water. In this case, permanganate ions transform into less dangerous manganese(II) cations:
• 2KMnO4 + 5H2O2 + 6CH3COOH =
• 2Mn(CH3COO)2 + 5O2 + 2CH3COOK + 8H2O

• USEFUL TIPS

Panteleev Pavel Alexandrovich

The work provides explanations for the appearance of color in various compounds, and also examines the properties of chameleon substances.

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Chemistry of color. Chameleon substances

Section: natural science

Completed by: Panteleev Pavel Nikolaevich,

Student 11 "A" class

Secondary school No. 1148

them. F. M. Dostoevsky

Teacher: Karmatskaya Lyubov Aleksandrovna

1. Introduction. Page 2

2. Nature of color:

2.1. organic substances; Page 3

2.2. inorganic substances. Page 4

3. The impact of the environment on color. Page 5

4. Chameleon substances. Page 7

5. Experimental part:

5.1. Transition of chromate to dichromate and vice versa; Page 8

5.2. Oxidizing properties of chromium (VI) salts; Page 9

5.3. Oxidation of ethanol with a chromium mixture. Page 10

6. Photochromism. Page 10

7. Conclusions. Page 13

8.List of sources used. Page 14

1. Introduction.

At first glance, it may seem difficult to explain the nature of color. Why do substances have different colors? How does color come into being?

Interestingly, in the depths of the ocean there live creatures in whose bodies blue blood flows. One of these representatives is holothurians. Moreover, the blood of fish caught in the sea is red, like the blood of many other large creatures.

What determines the color of various substances?

First of all, color depends not only on how the substance is colored, but also on how it is illuminated. After all, in the dark everything seems black. Color is also determined by the chemical structures that predominate in the substance: for example, the color of plant leaves is not only green, but also blue, purple, etc. This is explained by the fact that in such plants, in addition to chlorophyll, which gives the green color, other compounds predominate.

Blue blood in sea cucumbers is explained by the fact that their pigment, which provides the color of blood, contains vanadium instead of iron. It is its compounds that give the blue color to the liquid contained in holothurians. In the depths where they live, the oxygen content in the water is very low and they have to adapt to these conditions, so compounds have arisen in the organisms that are completely different from those of the inhabitants of the air environment.

But we have not yet answered the questions posed above. In this work we will try to give complete, detailed answers to them. To do this, a number of studies should be carried out.

The purpose of this work will be to explain the appearance of color in various compounds, as well as to explore the properties of chameleon substances.

Tasks are set in accordance with the goal

In general, color is the result of the interaction of light with the molecules of a substance. This result is explained by several processes:
* interaction of magnetic vibrations of a light beam with molecules of matter;

* selective absorption of certain light waves by molecules with different structures;

* exposure to rays reflected or passed through a substance on the retina of the eye or on an optical device.

The basis for explaining color is the state of the electrons in the molecule: their mobility, their ability to move from one energy level to another, to move from one atom to another.

Color is associated with the mobility of electrons in a molecule of a substance and with the possibility of electrons moving to still free levels when absorbing the energy of a light quantum (elementary particle of light radiation).

Color arises as a result of the interaction of light quanta with electrons in the molecules of a substance. However, due to the fact that the state of electrons in atoms of metals and non-metals, organic and inorganic compounds is different, the mechanism for the appearance of color in substances is also different.

2.1 Color of organic compounds.

In organic substancesHaving color (and not all of them have this property), the molecules are similar in structure: they are, as a rule, large, consisting of dozens of atoms. For the appearance of color in this case, it is not the electrons of individual atoms that matter, but the state of the system of electrons of the entire molecule.

Ordinary sunlight is a stream of electromagnetic waves. A light wave is characterized by its length - the distance between adjacent peaks or two adjacent troughs. It is measured in nanometers (nm). The shorter the wave, the greater its energy, and vice versa.

The color of a substance depends on which waves (rays) of visible light it absorbs. If sunlight is not absorbed by a substance at all, but is reflected and scattered, the substance will appear white (colorless). If a substance absorbs all rays, then it appears black.

The process of absorption or reflection of certain rays of light is associated with the structural features of the molecule of a substance. The absorption of light flux is always associated with the transfer of energy to the electrons of the molecule of the substance. If a molecule contains s electrons (forming a spherical cloud), then to excite them and transfer them to another energy level requires a lot of energy. Therefore, compounds that have s electrons always appear colorless. At the same time, p-electrons (forming a figure eight cloud) are easily excited, since the connection they make is less strong. Such electrons are found in molecules that have conjugated double bonds. The longer the conjugation chain, the more p-electrons and the less energy is required to excite them. If the energy of visible light waves (wavelengths from 400 to 760 nm) is sufficient to excite electrons, the color that we see appears. The rays spent on exciting the molecule will be absorbed by it, and the unabsorbed ones will be perceived by us as the color of the substance.

2.2 Color of inorganic substances.

In inorganic substancescolor is due to electronic transitions and charge transfer from an atom of one element to an atom of another. The outer electron shell of the element plays a decisive role here.

As in organic substances, the appearance of color here is associated with the absorption and reflection of light.

In general, the color of a substance is the sum of the reflected waves (or those passing through the substance without delay). In this case, the color of a substance means that certain quanta are absorbed by it from the entire range of wavelengths of visible light. In molecules of colored substances, the energy levels of electrons are located close to each other. For example, substances: hydrogen, fluorine, nitrogen - seem colorless to us. This is due to the fact that visible light quanta are not absorbed by them, since they cannot transfer electrons to a higher level. That is, ultraviolet rays pass through these substances, which are not perceived by the human eye, therefore the substances themselves have no color for us. In colored substances, for example, chlorine, bromine, iodine, the electronic levels are located closer to each other, so the light quanta in them are able to transfer electrons from one state to another.

Experience. Effect of metal ion on the color of compounds.

Instruments and reagents: four test tubes, water, salts of iron (II), cobalt (II), nickel (II), copper (II).

Performing the experiment. Pour 20-30 ml of water into test tubes, add 0.2 g of iron, cobalt, nickel and copper salts and mix until dissolved. The color of the iron solution turned yellow, cobalt - pink, nickel - green, and copper - blue.

Conclusion: As is known from chemistry, the structure of these compounds is the same, but they have a different number of d-electrons: iron - 6, cobalt - 7, nickel - 8, copper - 9. This number affects the color of the compounds. That's why the difference in color is visible.

3. The impact of the environment on color.

The ions in solution are surrounded by a shell of solvent. A layer of such molecules immediately adjacent to an ion is calledsolvation shell.

In solutions, ions can affect not only each other, but also the solvent molecules surrounding them, and those, in turn, affect the ions. When dissolved and as a result of solvation, color appears in a previously colorless ion. Replacing water with ammonia deepens the color. Ammonia molecules are more easily deformed and the color intensity increases.

Now Let us compare the color intensity of copper compounds.

Experiment No. 3.1. Comparison of color intensity of copper compounds.

Instruments and reagents: four test tubes, 1% CuSO solution 4, water, HCl, ammonia solution NH 3, 10% solution of potassium hexacyanoferrate(II).

Performing the experiment. Place 4 ml of CuSO in one test tube 4 and 30 ml H 2 O, in the other two - 3 ml CuSO 4 and 40 ml H 2 O. Add 15 ml of concentrated HCl to the first test tube - a yellow-green color appears, to the second - 5 ml of a 25% ammonia solution - a blue color appears, to the third - 2 ml of a 10% solution of potassium hexacyanoferrate(II) - we see a red color. brown sediment. Add CuSO solution to the last test tube 4 and leave it for control.

2+ + 4Cl - ⇌ 2- + 6H 2 O

2+ + 4NH 3 ⇌ 2+ + 6H 2 O

2 2 + 4- ⇌ Cu 2 + 12 H 2 O

Conclusion: When reducing the amount of reagent (substance involved in a chemical reaction), necessary for the formation of the compound, the color intensity increases. When new copper compounds are formed, charge transfer and color change occur.

4. Chameleon substances.

The concept of "chameleon" is known primarily as a biological, zoological term meaninga reptile that has the ability to change the color of its skin upon irritation, a change in the color of the environment, etc.

However, “chameleons” can also be found in chemistry. So what's the connection?

Let's turn to the chemical concept:
Chameleon substances are substances that change their color in chemical reactions and indicate changes in the environment under study. Let’s highlight the general thing – change in color (color). This is what connects these concepts. Chameleon substances have been known since ancient times. Old manuals on chemical analysis recommend using a “chameleon solution” to determine the sodium sulfite content of sodium sulfite in samples of unknown composition. 2 SO 3 , hydrogen peroxide H 2 O 2 or oxalic acid H 2 C 2 O 4 . “Chameleon solution” is a solution of potassium permanganate KMnO 4 , which during chemical reactions, depending on the environment, changes its color in different ways. For example, in an acidic environment, a bright purple solution of potassium permanganate becomes discolored due to the fact that from the permanganate ion MnO 4 - a cation is formed, i.e.positively charged ion Mn 2+ ; in a strongly alkaline environment from bright purple MnO 4 - produces green manganate ion MnO 4 2- . And in a neutral, slightly acidic or slightly alkaline environment, the final product of the reaction will be an insoluble black-brown precipitate of manganese dioxide MnO 2 .

We add that due to its oxidizing properties,those. the ability to donate electrons or take them from atoms of other elements,and visual changes in color in chemical reactions, potassium permanganate has found wide application in chemical analysis.

This means that in this case, the “chameleon solution” (potassium permanganate) is used as an indicator, i.e.a substance indicating the presence of a chemical reaction or change that has occurred in the test environment.
There are other substances called "chameleons". We will consider substances containing the chromium element Cr.

Potassium chromate - inorganic compound, metal saltpotassium And chromic acid with the formula K 2 CrO 4 , yellow crystals, soluble in water.

Potassium bichromate (potassium dichromate, potassium chromium) - K 2 Cr 2 O 7 . Inorganic compound, orange crystals, soluble in water. Highly toxic.

5. Experimental part.

Experiment No. 5.1. The transition of chromate to dichromate and back.

Instruments and reagents: potassium chromate solution K 2 СrO 4 , potassium bichromate solution K 2 Cr 2 O 7 , sulfuric acid, sodium hydroxide.

Performing the experiment. We add sulfuric acid to a solution of potassium chromate; as a result, the color of the solution changes from yellow to orange.

2K 2 CrO 4 + H 2 SO 4 = K 2 Cr 2 O 7 + K 2 SO 4 + H 2 O

I add alkali to the potassium dichromate solution, as a result the color of the solution changes from orange to yellow.

K 2 Cr 2 O 7 + 4NaOH = 2Na 2 CrO 4 + 2KOH + H 2 O

Conclusion: In an acidic environment, chromates are unstable, the yellow ion turns into a Cr ion 2 O 7 2- orange, and in an alkaline environment the reaction proceeds in the opposite direction:
2 Cr 2 O 4 2- + 2H + acidic medium - alkaline medium Cr 2 O 7 2- + H 2 O.

Oxidizing properties of chromium (VI) salts.

Instruments and reagents: potassium dichromate solution K 2 Cr 2 O 7 , sodium sulfite solution Na 2 SO 3 , sulfuric acid H 2SO4.

Performing the experiment. To solution K 2 Cr 2 O 7 acidified with sulfuric acid, add Na solution 2 SO 3. We observe a color change: the orange solution turned green-blue.

Conclusion: In an acidic environment, chromium is reduced by sodium sulfite from chromium (VI) to chromium (III): K 2 Cr 2 O 7 + 3Na 2 SO 3 + 4H 2 SO 4 = K 2 SO 4 + Cr 2 (SO 4 ) 3 + 3Na 2 SO 4 + 4H 2 O.

Experiment No. 5.4. Oxidation of ethanol with a chromium mixture.

Instruments and reagents: 5% solution of potassium dichromate K 2 Cr 2 O 7 , 20% sulfuric acid solution H 2 SO 4 , ethyl alcohol (ethanol).

Performing the experiment: To 2 ml of a 5% solution of potassium dichromate add 1 ml of a 20% solution of sulfuric acid and 0.5 ml of ethanol. We observe a strong darkening of the solution. Dilute the solution with water to better see its shade. We obtain a yellow-green solution.
TO 2 Cr 2 O 7 + 3C 2 H 5 OH+ H 2 SO 4 → 3CH 3 -COH + Cr 2 O 3 + K 2 SO 4 + 4H 2 O
Conclusion: In an acidic environment, ethyl alcohol is oxidized by potassium dichromate. This produces an aldehyde. This experiment shows the interaction of chemical chameleons with organic substances.

Experiment 5.4. clearly illustrates the principle by which indicators work to detect alcohol in the body. The principle is based on the specific enzymatic oxidation of ethanol, accompanied by the formation of hydrogen peroxide (H 2 O 2 ), causing the formation of a colored chromogen,those. an organic substance containing a chromophore group (a chemical group consisting of carbon, oxygen, and nitrogen atoms).

Thus, these indicators visually (on a color scale) show the alcohol content in a person’s saliva. They are used in medical institutions when establishing facts of alcohol consumption and alcohol intoxication. The scope of application of indicators is any situation where it is necessary to establish the fact of alcohol consumption: conducting pre-trip inspections of vehicle drivers, identifying drunk drivers on roads by traffic police, use for emergency diagnostics, as a means of self-control, etc.

6. Photochromism.

Let's get acquainted with an interesting phenomenon, where a change in the color of substances also occurs, photochromism.

Today, glasses with chameleon lenses are unlikely to surprise anyone. But the history of the discovery of unusual substances that change their color depending on the light is very interesting. In 1881, the English chemist Phipson received a letter from his friend Thomas Griffith in which he described his unusual observations. Griffith wrote that the front door of the post office, located opposite his windows, changes its color throughout the day - darkens when the sun is at its zenith, and brightens at dusk. Curious about the message, Phipson examined lithopone, the paint used to paint the post office door. His friend's observation was confirmed. Phipson was unable to explain the cause of the phenomenon. However, many researchers have become seriously interested in the reversible color reaction. And at the beginning of the twentieth century, they managed to synthesize several organic substances called “photochromes,” that is, “photosensitive paints.” Since Phipson's time, scientists have learned a lot about photochromes -substances that change color when exposed to light.

Photochromism, or tenebrescence, is the phenomenon of a reversible change in the color of a substance under the influence of visible light and ultraviolet radiation.

Exposure to light causes in a photochromic substance, atomic rearrangements, changes in the population of electronic levels. In parallel with the color change, the substance can change its refractive index, solubility, reactivity, electrical conductivity, and other chemical and physical characteristics. Photochromism is inherent in a limited number of organic and inorganic, natural and synthetic compounds.

There are chemical and physical photochromism:

• chemical photochromism: intramolecular and intermolecular reversible photochemical reactions (tautomerization (reversible isomerism), dissociation (cleavage), cis-trans isomerization, etc.);
• physical photochromism: the result of the transition of atoms or molecules into different states. The color change in this case is due to a change in the population of the electronic levels. Such photochromism is observed when a substance is exposed to only powerful light fluxes.

Photochromes in nature:

• Mineral tugtupit capable of changing color from white or pale pink to bright pink.

Photochromic materials

The following types of photochromic materials exist: liquid solutions and polymer films (high molecular weight compounds), containing photochromic organic compounds, glasses with silver halide microcrystals evenly distributed throughout their volume (compounds of silver with halogens), photolysis ( decay by light) which is caused by photochromism; crystals of alkali and alkaline earth metal halides, activated by various additives (for example, CaF 2/La,Ce; SrTiO 3 /Ni,Mo).

These materials are used as light filters of variable optical density (i.e., they regulate the flow of light) in means of protecting eyes and devices from light radiation, in laser technology, etc.

Photochromic lenses

Photochromic lens exposed to light, partially covered with paper. A second level of color is visible between the light and dark parts, as photochromic molecules are located on both surfaces of the lens polycarbonate and others plastics . Photochromic lenses usually darken in the presence of ultraviolet light and lighten in its absence in less than a minute, but the complete transition from one state to another occurs in 5 to 15 minutes.

Conclusions.

So, the color of different compounds depends on:

*from the interaction of light with molecules of matter;

*in organic substances, color arises as a result of the excitation of electrons of the element and their transition to other levels. The state of the electron system of the entire large molecule is important;

*in inorganic substances, color is due to electronic transitions and charge transfer from an atom of one element to an atom of another. The outer electron shell of the element plays a major role;

*the color of the compound is influenced by the external environment;

*The number of electrons in a compound plays an important role.

List of sources used

1. Artemenko A. I. “Organic chemistry and man” (theoretical foundations, in-depth course). Moscow, “Enlightenment”, 2000.

2. Fadeev G. N. “Chemistry and color” (a book for extracurricular reading). Moscow, “Enlightenment”, 1977.

Just two drops of glycerin - and potassium permanganate changes its color!

Complexity:

Danger:

Do this experiment at home

Why does the solution turn blue at first?

If you watch the chameleon closely, you will notice that within a few seconds of adding glycerin to the solution, it will turn blue. The blue color is formed by mixing violet (from MnO 4 - permanganate) and green (from MnO 4 2- manganate) solutions. However, it turns green quite quickly - there is less and less MnO 4 - and more MnO 4 2- in the solution.

Addition

Scientists were able to discover in what form manganese is capable of turning a solution blue. This occurs when it forms the hypomanganate ion MnO 4 3- . Here manganese is in the +5 oxidation state (Mn +5). However, MnO 4 3- is very unstable, and special conditions are required to obtain it, so it cannot be seen in our experience.

What happens to glycerin in our experiment?

Glycerol interacts with potassium permanganate, giving it its electrons. Glycerol was taken in our reaction in large excess (about 10 times more than potassium permanganate KMnO4). Under the conditions of our reaction, glycerol itself turns into glyceraldehyde, and then into glyceric acid.

Addition

As we have already found out, glycerol C 3 H 5 (OH) 3 is oxidized by potassium permanganate. Glycerol is a very complex organic molecule, and therefore reactions involving it are often complex. The oxidation of glycerol is a complex reaction during which many different substances are formed. Many of them exist for only a short time and are transformed into others, and some can be found in solution even after the reaction is completed. This situation is typical for all organic chemistry as a whole. Typically, those substances that are produced the most as a result of a chemical reaction are called the main products, and the rest are by-products.

In our case, the main product of glycerol oxidation with potassium permanganate is glyceric acid.

Why do we add calcium hydroxide Ca(OH) 2 to the KMnO 4 solution?

In an aqueous solution, calcium hydroxide Ca(OH) 2 breaks down into three charged particles (ions):

Ca(OH) 2 → Ca 2+ (solution) + 2OH - .

In transport, a store, a cafe or in a school classroom - everywhere we are surrounded by different people. And we behave differently in such places. Even if we do the same thing - for example, read a book. Surrounded by different people, we do it a little differently: somewhere slower, somewhere faster, sometimes we remember what we read well, and other times we can’t remember even a line the next day. Likewise, potassium permanganate, surrounded by OH ions, behaves in a special way. It takes electrons from glycerol “more gently”, without rushing anywhere. This is why we can observe a change in the color of the chameleon.

Addition

What happens if you don’t add a Ca(OH) 2 solution?

When an excess of OH - ions is present in a solution, such a solution is called alkaline (or is said to have an alkaline reaction). If, on the contrary, there is an excess of H + ions in the solution, such a solution is called acidic. Why "on the contrary"? Because together the OH - and H + ions form the water molecule H 2 O. But if the H + and OH - ions are present equally (that is, we actually have water), the solution is called neutral.

In an acidic solution, the active oxidizing agent KMnO 4 becomes extremely untrained, even rude. It very quickly takes electrons away from glycerol (as many as 5 at a time!), and manganese turns from Mn^+7 (in permanganate MnO 4 -) to Mn 2+:

MnO 4 - + 5e - → Mn 2+

The latter (Mn 2+) does not give the water any color. Therefore, in an acidic solution, potassium permanganate will discolor very quickly, and a chameleon will not turn out.

A similar situation will occur in the case of a neutral solution of potassium permanganate. Only we will not “lose” all the colors of the chameleon, as in an acidic solution, but only two - the green manganate MnO 4 2 will not be obtained, which means the blue color will also disappear.

Is it possible to make a chameleon using anything other than KMnO 4?

Can! A chromium (Cr) chameleon will have the following color:

orange (dichromate Cr 2 O 7 2-) → green (Cr 3+) → blue (Cr 2+).

Another chameleon - from vanadium (V):

yellow (VO 3+) → blue (VO 2+) → green (V 3+) → purple (V 2+).

It’s just much more difficult to make solutions of chromium or vanadium compounds change their color as beautifully as happens in the case of manganese (potassium permanganate). In addition, you will have to constantly add new substances to the mixture. Therefore, a real chameleon - one that will change its color “on its own” - can only be obtained from potassium permanganate.

Addition

Manganese Mn, like chromium Cr and vanadium V, are transition metals - a large group of chemical elements that have a whole range of interesting properties. One of the features of transition metals is the bright and varied color of compounds and their solutions.

For example, it is easy to obtain a chemical rainbow from solutions of transition metal compounds:

Every Hunter Wants to Know Where the Pheasant Sits:

Red (iron (III) thiocyanate Fe(SCN) 3), iron Fe;

Orange (dichromate Cr 2 O 7 2-), chromium Cr;

Yellow (VO 3+), vanadium V;

Green (nickel nitrate, Ni(NO 3) 2), nickel Ni;

Blue (copper sulfate, CuSO 4), copper Cu;

Blue (tetrachlorocobaltate, 2-), cobalt Co;

Violet (permanganate MnO 4 -), manganese Mn.

Development of the experiment

How to change the chameleon further?

Is it possible to reverse the reaction and get a purple solution again?

Some chemical reactions can occur in one direction or in the opposite direction. Such reactions are called reversible and, compared to the total number of chemical reactions, not so many of them are known. You can reverse the reaction by creating special conditions (for example, high heating of the reaction mixture) or by adding some new reagent. The oxidation of glycerol with potassium permanganate KMnO 4 is not a reaction of this type. Moreover, within the framework of our experiment, it is impossible to reverse this reaction. Therefore, we will not be able to force the chameleon to change its color in the reverse order.

Addition

Let's see if there is a way to convert our chameleon?

First a simple question: can oxidized glycerol (glyceric acid) turn manganese dioxide MnO 2 back into violet potassium permanganate KMnO 4? No, he can not. Even if we help him a lot (for example, heat the solution). And all because KMnO 4 is a strong oxidizing agent (we discussed this a little higher), while glyceric acid has weak oxidizing properties. It is incredibly difficult for a weak oxidizing agent to oppose anything to a strong one!

Is it possible to convert MnO 2 back to KMnO 4 using other reagents? Yes, you can. But for this you will have to work in a real chemical laboratory! One of the laboratory methods for producing KMnO 4 is the interaction of MnO 2 with chlorine Cl 2 in the presence of excess potassium hydroxide KOH:

2MnO 2 + 3Cl 2 + 8KOH → 2KMnO 4 + 6KCl + 4 H 2 O

You cannot carry out such a reaction at home - it is both difficult (you will need special equipment) and unsafe. And she herself will have little in common with the bright and beautiful chameleon from our experience.

Ministry of Education of the Russian Federation

"Chemical chameleon or the story of potassium permanganate"

The work was completed

Student of class 10 "A"

Mileikovskaya Zoya

And a student of grade 11 "B"

Kisin Sergey

Supervisor:

Saint Petersburg

Introduction. Goals and objectives 3

Main part 5

What is potassium permanganate 5

Solubility 5

Discovery of KMnO₄ 6

6 ways to get it

Other methods for obtaining permanganate 7

Chemical properties 9

Oxidizing properties depending on the environment 11

Heat decomposition 12

Application of potassium permanganate 12

Help with misuse 15

KMnO₄ in horticulture 16

Conclusion 16

Literature 17

Appendix 18

Experiments with potassium permanganate 18

II experience 19

III experience 20

Introduction. Goals and objectives

Potassium permanganate KMnO₄ is one of the most powerful oxidizing agents, very common. These are almost black shiny crystals. The solution in water has an intense crimson color, which appears to be due to MnO₄ ions. This substance, commonly called potassium permanganate, is a good disinfectant. Why is KMnO₄ an oxidizing agent, a disinfectant, but because its oxidation state of manganese is +7. And now it becomes clear why, when going on a hike, they remind you to take some potassium permanganate with you in order to make the water from a river or lake clean. It turns out that potassium permanganate oxidizes water in the light and the impurities in it. If you dissolve several crystals of potassium permanganate in water and wait a while, you will notice that the crimson color will gradually become paler and then completely disappear, a brown coating will remain on the walls of the vessel, this is manganese oxide that has precipitated - MnO₂ ↓.

4KMnO₄ + 2H₂O → 4MnO₂ + 4KOH + 3O₂

Mn + 3ē → Mn 3 4

2O – 4ē → O₂ 4 3

Bacteria and organic substances are oxidized by oxygen or die under the influence of an alkaline environment. The water can be filtered and used. This means that the permanganate solution can only be stored in a dark container.

The more you study chemistry, the more interesting things you learn about substances. And you can explain more about the phenomena that are happening.

We set ourselves a goal: to learn more about a substance that, despite any circumstances, is found in almost every home medicine cabinet. Also about a substance that is constantly used in natural history, physics and chemistry lessons to show the phenomenon of diffusion and coloring water a beautiful pink color, a substance from which oxygen is obtained in chemistry lessons, and also with the help of potassium permanganate, chlorine is obtained from hydrochloric acid.

The main task is to study this interesting substance in more depth, and since it does not exist in nature, to find out who first obtained it and how else it can be obtained, what properties it has, and what properties it is used for.

Main part

What is potassium permanganate

Solubility

Dissolved KMnO₄ are dark purple crystals with a metallic luster. It can be assumed that the solubility of permanganate is good, but it seems so. In fact, the solubility of this salt at room temperature (20°C) is only 6.4 g per 100 g of water. However, the solution is intensely colored and appears concentrated. Solubility increases with increasing temperature.

Temperature °C
Solubility, g/100g water

The substance crystallizes in the form of beautiful dark purple prisms, almost black. Solutions have a dark crimson, and at high concentrations - violet color.

Discovery of KMnO₄

The Swedish scientist Gottlieb Johan Hahn devoted his research to the study of minerals and inorganic chemistry. Together with compatriot Wilhelm Karl Scheele, during the study of the mineral pyrolusite MnO₂ in 1774, they discovered manganese (obtained it in metallic form), and also obtained and studied the properties of a number of manganese compounds, including potassium permanganate.

Methods of obtaining

By fusing manganese dioxide MnO₂ with potassium carbonate and nitrate (K₂CO₃ and KNO₃) it created a green alloy that dissolves in water to form a beautiful green solution. Dark green crystals of potassium manganate K₂MnO₄ were isolated from this solution.

MnO₂ + K₂CO₃ + KNO₃ → K₂MnO₄ + KNO₂ + CO₂.

If the solution was left in the air, its color gradually changed, turning from green to crimson, and a dark brown precipitate formed. This was explained by the fact that in an aqueous solution, manganates spontaneously transform into salts of manganese acid HMnO₄ with the formation of manganese dioxide MnO₂.

3K₂MnO₄ + 2H₂O → 2KMnO₄ + MnO₂↓ + 4KOH

In this case, one MnO₄ ion oxidizes two other similar ions into MnO₄ ions, and itself is reduced, forming MnO₂.

The experiments were repeated with other components, oxidizing pyrolusite.

This may be oxidation by oxygen in the presence of alkali KOH

2MnO₂ + 4KOH + O₂ → 2K₂MnO₄ + 2H₂O

Or potassium nitrate in the presence of alkali.

MnO₂ + KOH + KNO₃ = K₂MnO₄ + KNO₂ + H₂O

But in any case, manganate gave permanganate.

The process of converting manganate into permanganate is reversible. Therefore, with an excess of hydroxyl ions, that is, alkali, the manganate solution can remain unchanged. But as the alkali concentration decreases, the green color quickly turns into crimson.

Other methods for obtaining permanganate

When strong oxidizing agents (for example, chlorine) act on a manganate solution, the latter is completely converted into permanganate.

2K₂MnO₄ + Cl₂ = 2KMnO₄ + 2KCl

There may be chemical or electrochemical oxidation of manganese compounds.

MnO₂ + Cl₂ + 8KOH → 2KMnO₄ + 6KCl + 4H₂O

Potassium manganate K₂MnO₄ can be subjected to electrolysis. This is the main industrial method of production.

K₂MnO₄ + 2H₂O → 2KMnO₄ + H₂ + 2KOH

2H + 2ē → H₂ MnO₄ - ē → MnO₄

Reduction oxidation

In industry, permanganate is also produced by electrolysis of concentrated potassium hydroxide KOH with a manganese anode Mn. During the electrolysis process, the anode material gradually dissolves to form a purple solution containing permanganate anions. Hydrogen is released at the cathode.

Mn + 2KOH + 6H₂O → 2KMnO₄ + 7H₂

cathode anode

2H + 2ē → H₂(reduction) Mn – 7ē → Mn(oxidation)

Potassium permanganate, moderately soluble in water, is released in the form of a precipitate and it would be tempting to produce sodium permanganate NaMnO₄ instead of the usual potassium permanganate. Sodium hydroxide is more readily available than potassium hydroxide. However, under these conditions it is not possible to isolate NaMnO₄; unlike potassium permanganate, it is perfectly soluble in water (at 20°C its solubility in water is 144 g per 100 g of water).

Chemical properties

According to the chemical properties, KMnO₄ is a strong oxidizing agent, since the oxidation state is +7, and it received its name from the permanganate naming system. When the degree of an element is high, a prefix is ​​added lane and suffix at.

Easily converts Fe into Fe, which is used in the analysis of the determination of Fe salts (ferrous iron).

2KMnO₄ + 8H₂SO₄ + 10FeSO₄ → 2MnSO₄ + 5Fe₂(SO₄)₃ + 8H₂O + K₂SO₄

· Discolors and turns slightly yellow.

· Sulfurous acid turns into sulfuric acid.

2KMnO₄ + 5H₂SO₃ → 2H₂SO₄ + K₂SO₄ + 2MnSO₄ + 3H₂O

· Chlorine is released from hydrochloric acid.

2KMnO₄ + 16HCL → 5CL₂ + 2KCL + 2MnCL₂ + 8H₂O

Mn +5ē → Mn 5 2

2CL – 2ē → CL 2 5

(this is a laboratory method for producing chlorine)

ü We must remember that chlorine is a toxic substance and this experiment must be carried out in a fume hood.

Permanganate is chemically incompatible with coal, sugar (sucrose) C₁₂H₂₂O₄, and flammable liquids - an explosion may occur.

2KMnO₄ + C → K₂MnO₄ + CO₂ + MnO₂

without breaking the C–C bond.

2KMnO₄ + 5C₂H₅OH + 3H₂SO₄ → 2MnSO₄ + 5C₂H₄O₂ + K₂SO₄

(alcohol) (acid)

2KMnO₄ + 3C₂H₄ + 4H₂O → 3CH₂ – CH₂ + 2MnO₂ + 2KOH

(ethene) OH OH (ethylene oxidation)

When KMnO₄ reacts with concentrated sulfuric acid, an oxide is formed.

2KMnO₄ + H₂SO₄(conc.) → Mn₂O₇ + H₂O + K₂SO₄

ü Mn₂O₇ - oily dark green liquid. The reaction goes well with dry salt. Mn₂O₇ is the only liquid metal oxide; tmelt = 5.9°, unstable, easily explodes. At t = 55° or during shock. Alcohol ignites on contact with it.

This, by the way, is one of the ways to light a spirit lamp without matches. Place several KMnO₄ crystals in a porcelain cup, carefully add 1-2 drops of H₂SO₄ (conc.) and carefully mix the mixture with a glass rod. Then touch the wick of the alcohol lamp with a stick.

Mn₂O₇ + C₂H₅OH + 12H₂SO₄ → 12MnSO₄ + 10CO₂ + 27H₂O

KMnO₄ is an oxidizing agent for both inorganic and organic substances. The more electrons an oxidizing agent is able to accept during a reaction, the greater the number of moles of another substance it will oxidize. And the number of electrons depends on the reaction conditions, for example, on acidity.

An acidified strong solution of KMnO₄ literally burns many organic substances, turning them into CO₂ and H₂O.

For example, oxidation of oxalic acid

H₂C₂O₄ + 2KMnO₄ + 3H₂SO₄ = 10CO₂ + MnSO₄ + K₂SO₄ + 8H₂O

2C – 2ē → 2C 5 oxidation

Mn + 5ē → Mn 2 recovery

§ Chemists use this to wash laboratory glassware that is heavily contaminated with poorly washed off remains of organic substances; it is also sometimes used when washing windows (carefully).

Oxidizing properties depending on the environment

Depending on the acidic environment, KMnO₄ can be reduced to different products:

· Acidic environment

In an acidic environment – ​​to manganese (II) compounds.

2KMnO₄ + 4K₂SO₃ + 3H₂SO₄ → 2MnSO₄ + 5K₂SO₄ + 3H₂O

The solution becomes discolored, since manganese (II) compounds are colorless.

· Neutral environment

In a neutral environment – ​​to manganese (IV) compounds.

2KMnO₄ + 3K₂SO₃ + H₂O → 2MnO₂↓ + 3K₂SO₄ + 2KOH

MnO₂ gives the solution a brown tint as it precipitates.

· Highly alkaline environment

In a strongly alkaline environment – ​​up to manganese (VI) compounds.

2KMnO₄ + K₂SO₃ + 2KOH → 2K₂MnO₄ + K₂SO₄ + H₂O

An emerald green solution of potassium manganate is formed. This solution can also be obtained using the flame of an alcohol lamp, a not very strong solution of KMnO₄ with the addition of solid alkali KOH.

4 KMnO₄ + 4KOH → 4K₂MnO₄ + O₂ + 2H₂O

Heat decomposition

When heated, KMnO₄ decomposes. This is often used to produce oxygen in the laboratory. T = 200°C is sufficient.

KMnO₄ → K₂MnO₄ + MnO₂ + O₂

A smoldering splinter introduced into a test tube with released oxygen flares up with a bright flame. You need to work carefully, insert a cotton filter into the hole so that solid substances of decomposition products do not enter with the flow of oxygen in the air.

Application of potassium permanganate

KMnO₄ is used again on the high oxidizing ability of the permanganate ion, which provides an antiseptic effect.

Dilute solutions (about 0.1%) of potassium permanganate have found widespread use in medicine, as an antiseptic for gargling, washing wounds, and treating burns. A diluted solution is used as an emetic for oral administration in case of some poisonings.

Upon contact with organic substances, atomic oxygen is released. The oxide formed during the reduction of the drug forms complex compounds with proteins - albumitans (due to this, KMnO₄ in small concentrations has an astringent effect, and in concentrated solutions it has an irritating, cauterizing and tanning effect). It also has a deodorizing effect. Effective in treating burns and ulcers.

The ability of KMnO₄ to neutralize some poisons underlies the use of its solutions for gastric lavage in case of poisoning with unknown poisons and food toxicant infections.

(When ingested, it is absorbed, producing a hematotoxic effect).

In particular, KMnO₄ can be used for poisoning with hydrocyanic acid HCN and phosphorus.

ü HCN is a liquid with the smell of bitter almonds, very poisonous.

2HCN + 2 KMnO₄ → N₂ + 2KOH + 2MnCO₃.

§ KOH is neutralized;

§ HCL gastric juice.

KOH + HCL → KCL + H₂O

And manganese carbonate turns into CO₂ and H₂O and soluble salt MnCL₂.

Permanganate can be used in other areas.

In 1888, the Russian scientist Egor Egorovich Wagner discovered the oxidation reaction of organic compounds containing an ethylene bond by treating these compounds with a 1% solution of KMnO₄ in an alkaline medium (Wagner reaction).

Using this method, he proved the unsaturated nature of a number of terpenes (he established the structure of pinene, the main component of Russian pine turpentines).

KMnO₄ in an alkaline solution is a weak oxidizing agent. For example, if ethylene C₂H₄ is ​​passed through this solution, the color of potassium permanganate disappears as ethylene is oxidized into ethane 1,2 diol or ethylene glycol.

3CH₂ = CH₂ + 2KMnO₄ + 4H₂O → 3CH₂ – CH₂ + MnO₂↓ + 2KOH

A brown suspension of MnO₂ dioxide is also formed. Discoloration of a cold dilute solution of KMnO₄ is a qualitative reaction to the presence of the carbon-carbon multiple C=C bond, since very few organic compounds are oxidized in this way.

The alkaline KMnO₄ solution washes laboratory glassware well from fats and other organic substances.

Solutions - concentrations of 3 g/l are widely used for toning photographs.

Permanganate in acidic solutions is a strong oxidizing agent and is widely used in titrimetric analysis; the sharp transition from violet (MnO₄ ions) to pale pink (Mn ions) makes the use of indicators unacceptable. MnO₄ ions oxidize H₂S, sulfides, ionides, bromides, chlorides, nitrites, and hydrogen peroxide.

2KMnO₄ + 5H₂O₂ + 3H₂SO₄ → 2MnSO₄ + K₂SO₄ + 8H₂O + 5O₂

The French chemist and physicist Gay-Lussac Joseph Louis introduced the method of volumetric analysis into chemistry. In 1787, C. Berthollet described the method of redox titration, including permanganatormy. This method can be used to quantify: oxalic acid, formic hydrogen sulfide, hydrogen peroxide, iron in salts (II). Manganese in manganese (II) salts, an indicator in this method is not required if the titrated solutions are colorless, so during titration the KMnO₄ solution should become discolored, and when the reaction is completed, each excess drop of the KMnO₄ solution will color the titrated solution pink.

In pyrotechnics it is used as an oxidizing agent, but rarely, since coloring substances are released when used.

Help with misuse

Dentistry often performs what seems like a strange procedure to treat gums. The gums are lubricated with a solution of potassium permanganate, and then hydrogen peroxide is applied. The released oxygen O₂ will be the main therapeutic agent, which is why the procedure is called “Oxygen baths”.

Different concentrations are used for different purposes:

Washing wounds
Gargling
For lubricating ulcerative and burn surfaces
For douching and gastric lavage

And if the use was an ill-conceived, concentrated solution, burns and irritation may occur.

In case of overdose: sharp pain in the mouth, abdomen, vomiting, the mucous membrane is swollen and purple. With low acidity of gastric juice - shortness of breath. Lethal dose for children:

o About – 3 g.

Lethal dose for adults:

o 0.3-0.5 g per kg of weight.

Treatment: methylene blue

1) 50ml of 1% solution;

2) Ascorbic acid intravenously – 30 ml of 5% solution.

KMnO₄ in horticulture

Gardeners in their practice often use potassium permanganate for two properties: oxidizing and a source of potassium and manganese. Potassium ion is needed by plants as a nutrient element, and the MnO₄ anion acts as an oxidizing agent on sources of disease: fungi, mold, etc., and also as a trace element.

KMnO₄ → K + MnO₄

A good folk recipe for increasing strawberry productivity. In early spring, remove last year's leaves from the garden bed, prepare a pink solution of potassium permanganate and pour the warm solution over the entire strawberry plantation from a watering can (rain).

Gardeners believe that they destroy all infections and increase productivity due to the fact that potassium permanganate does not have very high solubility and potassium ions are not washed out of the soil.

Conclusion

Potassium permanganate is an invariable representative of any home medicine cabinet. It is called the mineral chameleon. The ability to change color in an aqueous solution is violet-crimson, in the presence of acids it is red, and with strong dilution it is pink. And when, for example, H₂O₂ hydrogen peroxide is added, the color disappears.

This strong oxidizing agent has a disinfecting effect. Widely used in medicine, and as an oxidizing agent in many industries, in chemical laboratories.

Literature

v – Preparative chemistry;

v – “Synthesis of organic drugs”;

v Remi G. – “Course of Neoranic Chemistry” volume I.

v – “Popular library of chemical elements”. Moscow, science - 1983;

v Internet encyclopedia Wikipedia - www. wikipedia. org

Application

Experiments with potassium permanganate

Potassium permanganate dissolves in water. The solution turns pink, at first pink and then intense.

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III experience

When KMnO₄ crystals are exposed to cold concentrated sulfuric acid (a highly water-removing agent), it decomposes and manganese oxide is formed.

ü Mn₂O₇ - greenish-black oily liquid.

If you dip a glass rod in this liquid and bring it to the wick of an alcohol lamp, it lights up.

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The experiment can be modified - moisten a cotton swab with alcohol and squeeze the alcohol into a mixture of KMnO₄ and H₂SO₄, that is, into Mn₂O₇. A flash (oxidation) occurs.

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Potassium permanganate with glycerin

If you pour KMnO₄ into filter paper and moisten the salt with glycerin. Wrap it in a bag, then after seven minutes smoke appears and the bag catches fire.

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