The attention of kids is attracted by everything bright and unusual - for example, a rainbow in the sky. How distinct are its colors! But this is a rare pleasure - it is impossible to order such a "show". For a rainbow to appear, it must rain and shine at the same time. But you can make your own little rainbow - from four colors - at home, in a glass of water. And, of course, regardless of the weather. What do we need for a home experiment for a child? It is necessary to prepare 5 glass glasses; 10 st. l. sugar, poured into one container (a sugar bowl is quite suitable); 4 jars of pre-diluted food paint in 4 colors (red, yellow, green, blue); water; syringe without a needle; teaspoon and tablespoon. So let's start.

Experiment for children

1. Arrange the glasses in a row. In each of them we add a different amount of sugar: in the 1st - 1 tbsp. l. sugar, in the 2nd - 2 tbsp. l., in the 3rd - 3 tbsp. l., in the 4th - 4 tbsp. l.

2. In four glasses in a row, pour 3 tbsp. tablespoons of water, preferably warm, and mix. The fifth glass remains empty. By the way, sugar will melt in the first two glasses, but not in the rest.

3. Then, using a teaspoon, add a few drops of food coloring to each glass and mix. In the 1st - red, in the 2nd - yellow, in the 3rd - green, in the 4th - blue.

4. Now the fun part. In a clean glass, using a syringe without a needle, we begin to add the contents of the glasses, starting from the 4th, where there is the most sugar, and in order - in the countdown. We try to pour along the edge of the glass wall.

5. 4 multi-colored layers are formed in the glass - the lowest blue, then green, yellow and red. They don't mix. And it turned out such a striped "jelly", bright and beautiful.

Explanation of experience for children

What is the secret of this experience for children? The concentration of sugar in each colored liquid was different. The more sugar, the higher the density of the water, the “heavier” it is, and the lower this layer will be in the glass. The red liquid with the lowest sugar content, and therefore the lowest density, will be at the very top, and with the highest - blue - at the bottom.

ALCHEMIST'S "PHILOSOPHER'S STONE" RECIPE

Chemical rainbow.

A mixture of ether and ammonia changes the color of the flowers: the red poppy turns purple, and the white rose turns yellow.

In one medieval alchemical manuscript, the following recipe is given for making a "philosopher's stone", supposedly able to turn base metals into gold:

"To make the elixir of the sages, which is called the philosopher's stone, take, my son, philosophical mercury and heat it up until it turns into a green lion. After that, heat it up more and it will turn into a red lion. alcohol, evaporate the product, and the mercury will turn into a gummy substance that can be cut with a knife. Put it in a clay-smeared retort and slowly distill."

How to decipher these mysterious phrases?

When translated into modern language the passage will take the following form: "To obtain acetic lead, it is necessary to heat metallic lead until it is oxidized into red lead, which should be treated with a solution of acetic acid and distilled."

FORGOTTEN WORD

In one very old fable there is such an expression: "Having pretty much smashed your nose ..." In our time, perhaps, not everyone will understand him. The word "sandalite" comes from the word "sandal", as the sandal tree, which grows in tropical regions, is briefly called.

In the old days, before the discovery of artificial organic dyes, sandalwood was very popular among dyers. Now it is difficult to get it, but still sometimes it is possible.

Boil sandalwood shavings in a weak solution of lye (caustic soda or potassium), divide the broth into two portions and add calcium chloride solution to one of them, and barium chloride to the other. Get the so-called purple varnishes, which were used relatively recently in the wallpaper industry.

Infuse the other part of the chips with alcohol; alcohol will turn into a very beautiful red color. That is why sandalwood was used in winemaking in the old days, because with its help "grape wines" were prepared from water, alcohol and caramel without ... a single grape berry. No wonder at the end of the 80s of the past (XIX - Note. ed.) for centuries, more “grape wines” were exported from Moscow than were imported into it, although, as you know, grapes do not grow in Moscow ...

Hence the expression "sandalize the nose" is understandable. It is known that from the immoderate use of alcoholic beverages the nose turns red, while sandalwood also paints red.

ENTERTAINING CHEMICAL EXPERIENCES

You can show that chemistry is not a boring science by doing a series of spectacular experiments, the result of which will make many change their minds about chemistry and convince them that it is interesting to study it.

Be careful doing the experiments described here. Do not taste any substances at all and wash your hands thoroughly after work. Handle as few substances as possible, especially harmful ones.

Do not prematurely try to do independent research: "What, they say, will I succeed if I pour myself into this liquid and pour that one over?" or "Come on, crush these crystals with that powder: what will come of it?" and so on. A very bad thing can come out: poisonous gas can be released, an explosion can occur. The most innocent common substances in combination with others of the same, individually safe, can form a new, extremely dangerous substance.

Curiosity is a laudable quality, but in this case let knowledge and caution prevail over it.

CLEAN AN EGG WITHOUT BREAKING THE SHELL

The French have a saying: "You can't cook scrambled eggs without breaking eggs." The chemist, hearing her, can only shrug his shoulders. There is nothing easier and simpler than peeling an egg without breaking its shell.

I would like to think that you have already guessed how to do this, if you know that the hard shell of the egg is the same carbonic lime, like chalk or marble. One has only to lower the egg into a weak solution of hydrochloric acid.

IMAGINARY ERROR OF PHYSICISTS

Physics teaches that when you mix blue and yellow colors, you get a composite green color. All painters are convinced of the same. And yet I can easily prove to you that such an assertion is false. Blue and yellow are complementary colors that cancel each other out. Solutions of blue and yellow paint, when drained, give a colorless mixture.

See for yourself. In this glass, as you can see, there is a blue liquid, in this one - yellow. I pour them into a third glass. Before you - transparent water: blue and yellow colors destroyed each other ...

I am almost sure that I will not mislead you and you yourself will unravel the mystery of such a "violation" of the laws of optics; but whoever has not yet seen the experiments I have shown before, he, perhaps, will be put by this experience into a dead end.

You say that in the first glass I had an alkaline solution of litmus (blue), in the other - the same solution of methyl orange (yellow), and in the third, where I poured the contents of the first two, - chlorine water.

You are right: it was!

RAINBOW FROM WATER AND WATER FROM RAINBOW

A magnificent sight is a rainbow that appears in the sky when the rain has not yet passed, and the sun has already peeped out from behind the clouds.

No less beautiful is the gamut of colors of the solar spectrum, which is obtained on a white wall if the sunbeam illuminating it passes through a glass prism along the way and decomposes into its component colors.

But you can get all the colors of the rainbow and a purely chemical way.

This bottle is filled with wonderful water.

There are seven glasses on the table, according to the number of colors in the spectrum. I pour water into each of them, and in front of you is the whole gamut of colors: red, orange, yellow, green, blue, blue and purple.

Great English physicist Newton, whose name, I hope you know, not only decomposed the white color into seven colors, but also proved the opposite, that, merging with each other, they give the impression of white to our eyes.

The water I have just shown has the same property. We will now test Newton's instructions chemically by pouring all of our colored liquids back into the bottle.

But where do I take her? Oh! Absentmindedly, he removed it from the table and placed it on a shelf. We take it out of there and pour the contents of the glasses into it.

Red, orange, yellow, etc. liquids are poured one by one into the bottle, and here in front of you it is again full of clear water.

A beautiful and effective focus, but it is not so easy to do it in full with all seven colors of the spectrum. Firstly, for this it is necessary to select seven organic colors that dissolve easily and quickly in a weak solution of alkali and give colors close to the spectral ones. Phenolphthalein is quite suitable for red, methyl orange for yellow, a mixture of them for orange, chlorophyll for green, litmus for blue, it is in a stronger solution for blue and aniline violet for violet.

All of them must be tested before the experiment and selected in sufficient, but not excessive, quantities so that their solutions remain transparent. To make the presence of paints or their strong solutions at the bottom of the glasses invisible to the audience, the bottom of the latter at the very bottom can be pasted around with a narrow ribbon cut out of black paper. From a distance, black pieces of paper merge with the black surface of the table and the glasses seem completely empty. To make the paint mix with water faster, you can, while pouring water, hold the bottle in your right hand, take a glass with your left hand, covering the piece of paper pasted on the bottom with your palm, and slightly shake the liquid.

The most difficult thing in this trick is to ensure that the solutions merged together quickly and completely lose their color.

To do this, a second bottle is hidden on the table shelf, exactly the same as the one from which a weak solution of alkali (for example, caustic soda) is poured into glasses.

What you took to be absent-mindedness on my part was a common device used by conjurers to substitute one object for another.

Having placed the bottle on a shelf hidden from you by the front of the table, I took out another one of the same kind, with the same amount of liquid as was left in the first bottle. Only the liquid in it was different. It was chlorine water, bleaching organic paints.

INCREDIBLE FLOWER COLOR

An interesting summer chemical work is the change in the natural color of flowers, both plucked and remaining on the stem or branches. No matter how simple these experiments are, they make a great impression on the uninitiated in the secrets of chemistry and contribute to the awakening of interest in chemistry.

The best way to change the color of pink, blue and purple flowers is a mixture of ammonia and sulfuric ether (by the way, so called by the method of obtaining the action of sulfuric acid on alcohol, and not by composition, since there is no sulfur in it). Ether is flammable; smoking during experiments with it is prohibited.

Lowering a freshly picked flower with a stalk into the indicated mixture, after a few minutes they notice a change in its color. It works especially well with pink geranium, purple periwinkle, night violet, red and pink wild roses and garden roses, pink carnations, bluebells and garden doves. At the same time, variegated flowers are painted while preserving the pattern, changing only its colors. So, purple sweet peas acquire a dark blue color of the upper and bright green of the lower petal. Wild carnation is stained with dark brown and green stripes, etc. The red poppy turns deep purple, the white rose turns yellow. Only yellow flowers do not change their color, all the rest acquire a new one.

Many flowers do not even need to be plucked; it is enough to moisten them with the indicated liquid or hold them over a glass with it. Such is the fuchsia, which at the same time acquires a yellow, blue and green color, gradually returning to its natural color.

GOLD SOLUTION AND DISSOLVED

In the charming fairy tale "What the wind told about Voldemar Do and his daughters," Andersen describes the medieval gold maker as follows:

"Voldemar Do was proud and brave, but also knowledgeable. He knew a lot. Everyone saw it, everyone whispered about it. The fire burned in his room even in summer, and the door was always locked; he worked there day and night, but did not he liked to talk about his work: the forces of nature must be tested in silence.Soon, soon he would find the best, most precious thing in the world - red gold.

From smoke and ashes, from worries and sleepless nights, Voldemar's hair and beard turned gray, the skin on his face wrinkled and turned yellow, but his eyes still burned with a greedy gleam in anticipation of gold, desired gold.

But on the first day of Easter, the bells rang! The sun played in the sky. Voldemar Do worked feverishly all night, brewed, cooled, stirred, distilled. He sighed heavily, prayed fervently, and sat at work, afraid to take a breath. His lamp went out, but the coals of the hearth illuminated his pale face and sunken eyes. Suddenly they expanded. Look into the glass vessel! Shines ... Burns like heat! Something bright and heavy! He lifts the vessel with a trembling hand and, choking with excitement, exclaims: "Gold! Gold!"

He straightened up and lifted high the treasure that lay in a large glass vessel. "Found, found! Gold!" - he shouted and handed the vessel to his daughters, but ... his hand trembled, the vessel fell to the floor and shattered. The last rainbow bubble of hope has burst."

Let us try, following the example of alchemists, to look for a way to obtain "gold from water".

While you were reading a passage from Andersen, I boiled water in two flasks. I pour boiling water out of them into a third, larger capacity, and cover it with a handkerchief. A moment of patience!

Ready! I take off my handkerchief and hand you the cooled flask.

What beauty, what brilliance! It is all filled with the smallest flakes of gold, which sparkle in the rays of the sun.

Then I put the flask on a grid lying on a tripod, light an alcohol lamp under the grid - and after a few minutes the "gold" was gone: it completely dissolved in boiling water.

There is no need, of course, to say that it was not gold.

In flasks I separately boiled solutions of lead acetate (poisonous!) in distilled water and potassium iodide. Merging them together, he obtained two new salts by the exchange decomposition of these salts - potassium acetate, which remained in solution, and lead iodide. The latter is soluble only in hot water, and when the solution is cooled, it precipitates out of it in the form of small scaly crystals with a golden sheen. (For decades, I kept a test tube with such grains, taken as a keepsake after the experience in the classroom at the institute's chemical laboratory. - Note. Yu.M.)

This is perhaps the most beautiful of all chemical experiments.

Regarding the outward resemblance of crystalline lead iodide to grains of gold and its solubility in water, I would like to say a few words about the mistake of medieval alchemists and about the possibility of actually obtaining gold from other substances.

Alchemists believed in the existence of primary matter and did not distinguish between complex and simple substances. Their mistake was that they turned all their attention to physical properties bodies, not on them chemical composition. They hoped that by combining different substances, which have individual properties of gold, you can eventually get the gold itself. In particular, they were captivated by the idea of ​​turning heavy and shiny mercury into gold, giving it hardness and yellow color. That is why they usually mixed it for this with hard and yellow sulfur. In their opinion, sulfur was supposed to give mercury the missing properties of the latter.

In this case, they fell into a deep mistake, since, when combined, substances lose their physical properties and acquire new ones. So, sulfur, combining with mercury, did not give gold at all, and not even a new metal, but red paint - cinnabar.

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Elements of entertainment in extracurricular activities.

The great advantage of chemistry over other subjects is that

that her teaching can include beautiful experiments.

The report is devoted to the elements of entertainment in extracurricular activities.

We give a description of experimental experiments in chemistry,

which can be carried out in the classroom, extracurricular and extracurricular activities and at chemical evenings.

These experiments, according to curriculum, it is desirable to carry out at the end of the III quarter of the 8th grade. After students have completed topics such as

Topic 4 "Water. Solutions. Bases",

Topic 5 "Generalization of information about the main classes of inorganic compounds";

Theme7" chemical bond".

It is not bad to conduct experiments also at the end of the study of the chemistry course, i.e. at the end of grade 11, when students are engaged in generalization and repetition of the material. In this way, they will be able to explain facts unknown at the level of the 8th grade.

Experience I . Chemical rainbow.

Description.

In seven large test tubes placed in a demonstration rack with a white background, pour the solutions in pairs:

1- iron (III) chloride and potassium thiocyanate (red color);

2- potassium chromate solution is acidified with H 2 SO 4 (orange color);

3- lead nitrate and potassium iodide (yellow);

4-nickel(II) sulfate and sodium hydroxide (green);

5- copper (II) sulfate and sodium hydroxide (blue color);

6- copper (II) sulfate and ammonia solution (blue color);

7- cobalt (II) chloride and potassium thiocyanate (purple).

1. FeCl 3 + 3KCNS Fe(CNS) 3 + 3KCl

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

3. Pb(NO 3) 2 + 2KJ PbJ 2 + 2KNO 3

4. NiSO 4 + 2NaOH Ni (OH) 2 + Na 2 SO 4

5. CuSO 4 + 2NaOH Cu (OH) 2 + 2Na 2 SO 4

6. CuSO 4 + 4NH 3 SO 4

7. CoCl 2 + 2KCNS Co(CNS) 2 + 2KCl

Note.

The experience is very simple, but effective, thanks to the brightness of the substances obtained during the reaction. Students can remember how to write equations for chemical reactions. For experience, you can involve students.

Experience II . Fireworks in liquid.

Description.

Pour 50 ml of ethyl alcohol into a graduated cylinder. Through a pipette, which is lowered to the bottom of the cylinder, we introduce 40 ml of concentrated sulfuric acid. Thus, two layers of liquid are formed in the cylinder with a clearly visible boundary: the upper layer is alcohol, the lower one is sulfuric acid We throw some small crystals of potassium permanganate into the cylinder. Having reached the interface, the crystals begin to flash - here we have fireworks. The appearance of flashes is due to the fact that upon contact with sulfuric acid, manganese anhydride Mn 2 O 7 is formed on the surface of salt crystals - the strongest oxidizing agent that ignites a small amount of alcohol:

2KMnO 4 + H 2 SO 4 Mn 2 O 7 + K 2 SO 4 + H 2 O.

Mn 2 O 7 is a greenish-brown liquid, unstable and, in contact with combustible substances, ignites them.

Note.

Also a very nice experience. Here, students can repeat redox reactions.

Experience III. Red prisms.

Description.

Mix 10 g of potassium dichromate with 40 ml of concentrated hydrochloric acid and add 15-20 ml of water. We heat the mixture a little, and the salt crystals will go into solution. After dissolving potassium dichromate, the solution is cooled with water. Very beautiful red crystals fall out in the form of prisms, which are the potassium salt of chlorochromic acid KCrO 3 Cl, according to the reaction equation:

K 2 Cr 2 O 7 + 2HCl 2KCrO 3 Cl + H 2 O.

Note.

After studying topic7 “Chemical bond” (in particular the subtopic “ Crystal lattices”), this experience will be very useful.

Experience IV. Burning snow.

Description.

We pour snow into an iron tin can and slightly compact it. Then we make a recess in it (about ¼ of the height of the can), put a small piece of calcium carbide there and cover it with snow on top. We bring a lit match to the snow - a flame will appear, “the snow is burning”.

Calcium carbide slowly reacts with snow to form acetylene, which burns when ignited.

CaC 2 + 2H 2 O Ca (OH) 2 + C 2 H 2.

2C 2 H 2 + 5O 2 4CO 2 + 2H 2 O + Q.

Note.

Experience allows you to show facts that will be studied in subsequent sections of chemistry (org.chemistry).

Experience V. Storm in a glass.

Description.

Pour 5 g of benzoic acid into a 500 ml beaker and place a sprig of pine. Close the glass with a porcelain cup cold water and heat it over an alcohol lamp. The acid first melts, then turns into steam (evaporates), and the glass is filled with “snow”, which covers the branch with white flakes.

Note.

The experiment can be associated with the students' knowledge of the chemical bond.

Literature:

1. Journal “Chemistry and Life XXI Century” No. 9, 1999. (section "School club");

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burned with constant speed three inches an hour. By measuring the length of the remaining part, it was possible to determine quite accurately how much time had passed since the start of such clocks.

A double helix... There was something surprisingly familiar in this image. But what? Well, of course, the form double helix a DNA molecule has - True, a spiral of ropes burns out in a few hours, while the DNA spiral continues to copy itself throughout the life of the cell ...

Eret began to look for a living organism, experimenting with which he could confirm his guess. The choice fell on the ciliate shoe - a simple unicellular organism. “Usually ciliates are more active during the day than at night,” Ehret reasoned. “If it is possible, by acting on the DNA molecule, to disrupt the rhythm of its life, it can be considered proven that this molecule also serves as a biological clock mechanism.”

He chose a light beam as an instrument of influence. After a series of experiments, he managed to find out that by acting on the shoe alternately with ultraviolet radiation and white light, one can either greatly change the rhythm of life of the ciliate, or restore it again.

“Ultraviolet damages the DNA helix, but the cell can repair the damage if, after an ultraviolet pulse (exposed to it with white light,” Ehret concluded.

A little later, Ehret's conclusions were confirmed by other scientists who acted on the DNA molecule with various chemicals.

riyu, the essence of which boils down to this.

The DNA molecule, which in this case the American scientist called "chronon", is coiled in a tight spiral in the cell nucleus. When duplication of the molecule begins, the strands of such a helix diverge, and informational RNA is built on them, reaching the full length of a single strand of DNA-"chroion". At the same time, a number of interrelated chemical reactions take place, the ratio of the rates of which can be considered as the work of the regulating mechanism of the clock.

Eret considered his model as "a skeleton in which all the details are omitted ...". But in these details, apparently, the basis of the foundations of the biological clock is hidden. Which chemical reactions occur during duplication of DNA? ..

"RAINBOW" IN TEST TUBE

Two decades ago, the Soviet scientist B.P. Belousov discovered the new kind pulsating redox reactions. The liquid in the test tube changed its color right before our eyes: once it was red, now it is already blue, then it turned red again... The change in color proceeded strictly periodically.

Belousov spoke about the phenomenon he observed at one of the symposiums. The message was listened to with great interest, but no one, including the author himself, attached much importance to the fact that the initial components of pulsating reactions are organic matter, very similar in composition to the substances of a living cell, to the substances of DNA. Only in 1960 did another Soviet

Instruction

As Newton established, a white light beam is obtained as a result of the interaction of rays of different colors: red, orange, yellow, green, blue, indigo, violet. Each color is characterized by a specific wavelength and vibration frequency. At the boundary of transparent media, the speed and length of light waves change, the oscillation frequency remains the same. Each color has its own refractive index. The red beam deviates the least from the previous direction, orange a little more, then yellow, etc. The violet ray has the highest refractive index. If a glass prism is installed in the path of a light beam, then it will not only deviate, but also break up into several rays of different colors.

There is another phenomenon that is often confused with the moon - a halo, a multi-colored or ring around the lunar disk, which is formed due to the refraction of light passing through cloud crystals.