Dangerous experiments in chemistry. Elephant Toothpaste

A chemist is a very interesting and multifaceted profession, uniting many different specialists under its wing: chemists, chemical technologists, analytical chemists, petrochemists, chemistry teachers, pharmacists and many others. We decided together with them to celebrate the upcoming Chemist Day 2017, so we chose some interesting and impressive experiments in the field under consideration, which even those who are as far from the profession of a chemist as far as possible can repeat. The best chemistry experiments at home - read, watch and remember!

When is Chemist's Day celebrated?

Before we begin to consider our chemical experiments, let us clarify that the Chemist's Day is traditionally celebrated on the territory of the states of the post-Soviet space at the very end of spring, namely, on the last Sunday of May. This means that the date is not fixed: for example, in 2017 Chemist's Day is celebrated on May 28th. And if you work in the chemical industry, or study a specialty from this area, or are otherwise directly related to chemistry on duty, then you have every right to join the celebration on this day.

Chemical experiments at home

And now let's get down to the main thing, and we begin to perform interesting chemical experiments: it is best to do this together with young children, who will definitely perceive what is happening as a magic trick. Moreover, we tried to select such chemical experiments, the reagents for which can be easily obtained at a pharmacy or a store.

Experience No. 1 - Chemical traffic light

Let's start with a very simple and beautiful experiment, which received such a name by no means in vain, because the liquid participating in the experiment will change its color just to the colors of the traffic light - red, yellow and green.

You will need:

indigo carmine;
glucose;
caustic soda;
water;
2 clear glass containers.

Don't let the names of some of the ingredients scare you - you can easily buy glucose in tablets at a pharmacy, indigo carmine is sold in stores as a food coloring, and you can find caustic soda in a hardware store. It is better to take containers tall, with a wide base and a narrower neck, for example, flasks, so that it is more convenient to shake them.

But what is interesting about chemical experiments - there is an explanation for everything:

By mixing glucose with caustic soda, i.e. sodium hydroxide, we obtained an alkaline solution of glucose. Then, mixing it with a solution of indigo carmine, we oxidize the liquid with oxygen, with which it was saturated during the transfusion from the flask - this is the reason for the appearance of green color. Further, glucose begins to work as a reducing agent, gradually changing color to yellow. But by shaking the flask, we again saturate the liquid with oxygen, allowing the chemical reaction to go through this circle again.

How interesting it looks live, you will get an idea from this short video:

Experience No. 2 - A universal indicator of acidity from cabbage

Children love interesting chemical experiments with colorful liquids, it's no secret. But we, as adults, responsibly declare that such chemical experiments look very spectacular and curious. Therefore, we advise you to conduct another "color" experiment at home - a demonstration of the amazing properties of red cabbage. It, like many other vegetables and fruits, contains anthocyanins - natural dyes-indicators that change their color depending on the pH level - i.e. the degree of acidity of the environment. This property of cabbage is useful to us in order to obtain further multi-colored solutions.

What we need:

1/4 red cabbage;
lemon juice;
baking soda solution;
vinegar;
sugar solution;
drink type "Sprite";
disinfectant;
bleach;
water;
8 flasks or glasses.

Many substances on this list are quite dangerous, so be careful when doing simple chemistry experiments at home, wear gloves, goggles if possible. And do not let children get too close - they can knock over the reagents or the final contents of the colored cones, even want to try them, which should not be allowed.

Let's get started:

And how do these chemical experiments explain the color changes?

The fact is that light falls on all objects that we see - and it contains all the colors of the rainbow. Moreover, each color in the spectrum beam has its own wavelength, and molecules of different shapes, in turn, reflect and absorb these waves. The wave that is reflected from the molecule is the one that we see, and this determines what color we perceive - because other waves are simply absorbed. And depending on what substance we add to the indicator, it begins to reflect only rays of a certain color. Nothing complicated!

A slightly different version of this chemical experiment, with fewer reagents, see the video:

Experience number 3 - Dancing jelly worms

We continue to do chemical experiments at home - and we will conduct the third experiment on all our favorite jelly sweets in the form of worms. Even adults will find it funny, and children will be completely delighted.

Take the following ingredients:

a handful of jelly worms;
vinegar essence;
ordinary water;
baking soda;
glasses - 2 pcs.

When choosing the right candies, opt for smooth gooey worms, without sugar sprinkles. So that they are not heavy and move more easily, cut each candy lengthwise into two halves. So, we begin interesting chemical experiments:

Make a solution of warm water and 3 tablespoons of baking soda in one glass.
Put the worms in there and hold them there for about fifteen minutes.
Fill another deep glass with essence. Now you can slowly throw the jelly into the vinegar, watching how they begin to move up and down, which in some ways looks like a dance:

Why is this happening?

It's simple: baking soda, in which the worms are soaked for a quarter of an hour, is sodium bicarbonate, and the essence is an 80% solution of acetic acid. When they react, water, carbon dioxide in the form of small bubbles, and the sodium salt of acetic acid are formed. It is carbon dioxide in the form of bubbles that surrounds the worm, rises up, and then falls when they burst. But the process is still going on, causing the candy to rise on the resulting bubbles and descend until it is complete.

And if you are seriously interested in chemistry, and want Chemist's Day to become your professional holiday in the future, then you will probably be curious to watch the following video, which details the typical everyday life of chemistry students and their exciting educational and scientific activities:

Take it, tell your friends!

1. Lava lamp

Need: Salt, water, a glass of vegetable oil, a few food colors, a large transparent glass or glass jar.

An experience: Fill a glass 2/3 with water, pour vegetable oil into the water. The oil will float on the surface. Add food coloring to water and oil. Then slowly add 1 teaspoon of salt.

Explanation: Oil is lighter than water, so it floats on the surface, but salt is heavier than oil, so when you add salt to a glass, the oil and salt begin to sink to the bottom. As the salt breaks down, it releases oil particles and they rise to the surface. Food coloring will help make the experience more visual and spectacular.

2. Personal rainbow

Need: A container filled with water (bath, basin), flashlight, mirror, sheet of white paper.

An experience: Pour water into the container and put a mirror on the bottom. We direct the light of a flashlight to the mirror. The reflected light must be caught on paper, on which a rainbow should appear.

Explanation: The beam of light consists of several colors; when it passes through the water, it decomposes into its component parts - in the form of a rainbow.

3. Volcano

Need: Tray, sand, plastic bottle, food coloring, soda, vinegar.

An experience: A small volcano should be molded around a small plastic bottle made of clay or sand - for entourage. To cause an eruption, you should pour two tablespoons of soda into the bottle, pour in a quarter cup of warm water, add a little food coloring, and finally pour in a quarter cup of vinegar.

Explanation: When baking soda and vinegar come into contact, a violent reaction begins with the release of water, salt and carbon dioxide. Gas bubbles and push the contents out.

4. Grow crystals

Need: Salt, water, wire.

An experience: To get crystals, you need to prepare a supersaturated salt solution - one in which when a new portion is added, the salt does not dissolve. In this case, you need to keep the solution warm. To make the process go better, it is desirable that the water be distilled. When the solution is ready, it must be poured into a new container to get rid of the debris that is always in the salt. Further, a wire with a small loop at the end can be lowered into the solution. Put the jar in a warm place so that the liquid cools more slowly. After a few days, beautiful salt crystals will grow on the wire. If you get the hang of it, you can grow fairly large crystals or patterned crafts on twisted wire.

Explanation: As the water cools, the solubility of the salt decreases, and it begins to precipitate and settle on the walls of the vessel and on your wire.

5. Dancing coin

Need: A bottle, a coin that can be used to cover the neck of a bottle, water.

An experience: An empty unclosed bottle should be put in the freezer for a few minutes. Moisten a coin with water and cover the bottle taken out of the freezer with it. After a few seconds, the coin will begin to bounce and, hitting the neck of the bottle, make sounds similar to clicks.

Explanation: The coin is lifted by air, which has compressed in the freezer and occupied a smaller volume, and now has heated up and began to expand.

6. Colored milk

Need: Whole milk, food coloring, liquid detergent, cotton buds, plate.

An experience: Pour milk into a plate, add a few drops of dyes. Then you need to take a cotton swab, dip it in detergent and touch the wand to the very center of the plate with milk. The milk will move and the colors will mix.

Explanation: Detergent reacts with fat molecules in milk and sets them in motion. That is why skimmed milk is not suitable for the experiment.

7. Fireproof bill

Need: Ten-rouble note, tongs, matches or lighter, salt, 50% alcohol solution (1/2 part alcohol to 1/2 part water).

An experience: Add a pinch of salt to the alcohol solution, immerse the bill in the solution so that it is completely saturated. Remove the bill from the solution with tongs and allow excess liquid to drain. Set fire to a bill and watch it burn without burning.

Explanation: As a result of the combustion of ethyl alcohol, water, carbon dioxide and heat (energy) are formed. When you set fire to a bill, alcohol burns. The temperature at which it burns is not enough to evaporate the water that the paper bill is soaked in. As a result, all the alcohol burns out, the flame goes out, and the slightly damp ten remains intact.

9 Camera Obscura

You will need:

A camera that supports slow shutter speeds (up to 30 s);

Large sheet of thick cardboard;

Masking tape (for pasting cardboard);

A room with a view of anything;

Sunny day.

1. We seal the window with cardboard so that the light does not come from the street.

2. In the center we make an even hole (for a room 3 meters deep, the hole should be about 7-8 mm).

3. When the eyes get used to the darkness, an inverted street will be found on the walls of the room! The most visible effect will be on a bright sunny day.

4. Now the result can be shot on a camera at a slow shutter speed. A shutter speed of 10-30 seconds is fine.

This manual increases interest in the subject, develops cognitive, mental, research activities. Students analyze, compare, study and generalize the material, receive new information and practical skills. Students can conduct some experiments on their own at home, but most in the classroom of a chemical circle under the guidance of a teacher.

Download:

Preview:

town Novomikhailovsky

municipality

Tuapse district

"Chemical reactions around us"

Teacher:

Kozlenko

Alevtina Viktorovna

2015

« Volcano" on the table.Ammonium dichromate mixed with metallic magnesium is poured into the crucible (the mound in the center is moistened with alcohol). Light the "volcano" with a burning torch. The reaction is exothermic, proceeds rapidly, together with nitrogen, hot particles of chromium oxide (III) fly out and

burning magnesium. If you turn off the light, you get the impression of an erupting volcano, from the crater of which red-hot masses pour out:

(NH 4) 2 Cr 2 O 7 \u003d Cr 2 O 3 + 4H 2 O + N 2; 2Mg + O 2 \u003d 2MgO.

"Star Rain".Pour onto a sheet of clean paper, mixing thoroughly, three tablespoons of potassium permanganate, coal powder and reduced iron powder. The resulting mixture is poured into an iron crucible, which is fixed in the tripod ring and heated with the flame of an alcohol lamp. The reaction starts and the mixture is ejected

in the form of many sparks, giving the impression of "fiery rain".

Fireworks in the middle of the liquid. 5 ml of concentrated sulfuric acid is poured into the cylinder and 5 ml of ethyl alcohol is carefully poured along the wall of the cylinder, then a few crystals of potassium permanganate are thrown. Sparks appear on the border between two liquids, accompanied by crackling. Alcohol ignites when oxygen appears, which is formed when potassium permanganate reacts with sulfuric acid.

"Green Fire" . Boric acid with ethyl alcohol form an ester:

H 3 BO 3 + 3C 2 H 5 OH \u003d B (OS 2 H 5) + 3H 2 O

Pour 1 g of boric acid into a porcelain cup, add 10 ml of alcohol and 1 ml of sulfuric acid. The mixture is stirred with a glass rod and ignited. Ether vapor burns with a green flame.

Water ignites paper. In a porcelain cup, sodium peroxide is mixed with small pieces of filter paper. A few drops of water are dripped onto the prepared mixture. The paper is flammable.

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

2H 2 O 2 \u003d 2H 2 O + O 2 |

Multicolored flame.Various flame colors can be shown when chlorides are burned in alcohol. To do this, take clean porcelain cups with 2-3 ml of alcohol. 0.2-0.5 g of finely ground chlorides are added to the alcohol. The mixture is ignited. In each cup, the color of the flame is characteristic of the cation that is present in the salt: lithium - raspberry, sodium - yellow, potassium - violet, rubidium and cesium - pink-violet, calcium - brick red, barium - yellowish green, strontium - raspberry, etc.

Magic wands.Three chemical beakers are filled with solutions of litmus, methyl orange and phenolphthalein to about 3/4 of the volume.

In other glasses, solutions of hydrochloric acid and sodium hydroxide are prepared. Sodium hydroxide solution is collected with a glass tube. Stir the liquid in all the glasses with this tube, imperceptibly pouring out a small amount of the solution each time. The color of the liquid in the glasses will change. Then acid is collected in this way into the second tubeand mix liquids in glasses with it. The color of the indicators will again change dramatically.

Magic wand.For the experiment, a pre-prepared slurry of potassium permanganate and concentrated sulfuric acid is placed in porcelain cups. The glass rod is immersed in the freshly prepared oxidizing mixture. Quickly bring the stick to the damp wick of a spirit lamp or cotton wool soaked in alcohol, the wick ignites. (It is forbidden to bring a stick re-moistened with alcohol into the gruel.)

2KMnO 4 + H 2 SO 4 \u003d Mn 2 O 7 + K 2 SO 4 + H 2 O

6Mp 2 O 7 + 5C 2 H 5 OH + 12H 2 SO 4 \u003d l2MnSO 4 + 10CO 2 + 27H 2 O

The reaction takes place with the release of a large amount of heat, the alcohol ignites.

Self-igniting liquid.0.5 g of potassium permanganate crystals slightly ground in a mortar are placed in a porcelain cup, and then 3-4 drops of glycerin are applied from a pipette. After a while, the glycerin ignites:

14KMnO 4 + 3C 3 H 6 (OH) 3 \u003d 14MnO 2 + 9CO 2 + 5H 2 O + 14KOH

Combustion of various substancesin molten crystals.

Three tubes are 1/3 filled with white crystals of potassium nitrate. All three test tubes are fixed vertically in a rack and simultaneously heated with three spirit lamps. When the crystals melt,a piece of heated charcoal is lowered into the first test tube, a piece of heated sulfur into the second, and a little lit red phosphorus into the third. In the first test tube, the coal burns, "jumping" at the same time. In the second test tube, a piece of sulfur burns with a bright flame. In the third test tube, red phosphorus burns out, releasing such an amount of heat that the test tube melts.

Water is a catalyst.Mix gently on a glass plate

4 g of powdered iodine and 2 g of zinc dust. The reaction does not occur. A few drops of water are added to the mixture. An exothermic reaction begins with the release of a violet vapor of iodine, which reacts with zinc. The experiment is carried out under tension.

Self-ignition of paraffin.Fill 1/3 of the tubes with pieces of paraffin and heat to its boiling point. Boiling paraffin is poured from a test tube, from a height of about 20 cm, in a thin stream. Paraffin flares up and burns with a bright flame. (In a test tube, paraffin cannot ignite, since there is no air circulation. When paraffin is poured out in a thin stream, air access to it is facilitated. And since the temperature of the molten paraffin is higher than its ignition temperature, it flares up.)

Municipal Autonomous General Educational Institution

Secondary school No. 35

town Novomikhailovsky

municipality

Tuapse district

Entertaining experiences on the subject

"Chemistry in our house"

Teacher:

Kozlenko

Alevtina Viktorovna

2015

Smoke without fire. A few drops of concentrated hydrochloric acid are poured into one cleanly washed cylinder, and an ammonia solution is poured into the other. Both cylinders are closed with lids and placed at some distance from each other. Before the experiment show that the cylinders let. During the demonstration, the hydrochloric acid cylinder (on the walls) is turned upside down and placed on the cap of the ammonia cylinder. The lid is removed: white smoke is formed.

Golden Knife. To 200 ml of a saturated solution of copper sulphate, add 1 ml of sulfuric acid. Take a knife cleaned with sandpaper. Dip the knife for a few seconds in a solution of copper sulfate, take it out, rinse it and immediately wipe it dry with a towel. The knife becomes golden. It was covered with an even, shiny layer of copper.

Freezing glass.Ammonium nitrate is poured into a glass of water and placed on wet plywood, which freezes to the glass.

Color solutions. Crystal hydrates of copper, nickel, and cobalt salts are dehydrated before the experiment. After adding water to them, colored solutions are formed. Anhydrous white copper salt powder form blue color solution, green nickel green salt powder, blue salt powder 4 cobalt red.

Blood without a wound. For the experiment, use 100 ml of a 3% solution of ferric chloride FeCI 3 in 100 ml of a 3% solution of potassium thiocyanate KCNS. To demonstrate the experience, a children's polyethylene sword is used. Call someone from the audience to the stage. Wash the palm with a cotton swab with a solution of FeCI 3 , and the sword is moistened with a colorless solution of KCNS. Next, the sword is drawn across the palm: “blood” flows abundantly on the paper:

FeCl 3 + 3KCNS \u003d Fe (CNS) 3 + 3KCl

"Blood" from the palm is washed off with cotton wool moistened with a solution of sodium fluoride. They show the audience that there is no wound and the palm is completely clean.

Instant color "photo".Yellow and red blood salts, interacting with salts of heavy metals, give reaction products of different colors: yellow blood salt with iron (III) sulfate gives a blue color, with copper (II) salts - dark brown, with bismuth salts - yellow, with salts iron (II) - green. The above salt solutions on white paper make a drawing and dry it. Since the solutions are colorless, the paper remains uncolored. For the development of such drawings, a wet swab moistened with a solution of yellow blood salt is carried out on paper.

The transformation of liquid into jelly.Pour 100 g of sodium silicate solution into a beaker and add 5 ml of 24% hydrochloric acid solution. Stir the mixture of these solutions with a glass rod and hold the rod vertically in the solution. After 1-2 minutes, the rod no longer falls in the solution, because the liquid has thickened so that it does not pour out of the glass.

Chemical vacuum in a flask. Fill the flask with carbon dioxide. Pour a little concentrated solution of potassium hydroxide into it and close the opening of the bottle with a peeled hard-boiled egg, the surface of which is smeared with a thin layer of petroleum jelly. The egg gradually begins to be drawn into the bottle and, with a sharp sound of a shot, falls on her bottom.

(A vacuum was formed in the flask as a result of the reaction:

CO 2 + 2KOH \u003d K 2 CO 3 + H 2 O.

Outside air pressure pushes the egg.)

Fireproof handkerchief.The handkerchief is impregnated with a solution of sodium silicate, dried and folded. To demonstrate incombustibility, it is moistened with alcohol and set on fire. The handkerchief should be kept straightened with crucible tongs. The alcohol burns off, and the fabric impregnated with sodium silicate remains unharmed.

Sugar is on fire.Take a piece of refined sugar with tongs and try to set it on fire - the sugar does not light up. If this piece is sprinkled with ashes from a cigarette, and then set on fire with a match, the sugar lights up with a bright blue flame and quickly burns out.

(The ashes contain lithium compounds that act as a catalyst.)

Charcoal from sugar. Weigh out 30 g of powdered sugar and transfer it to a beaker. Pour ~ 12 ml of concentrated sulfuric acid into powdered sugar. Mix sugar and acid with a glass rod into a mushy mass. After a while, the mixture turns black and heats up, and soon a porous coal mass begins to crawl out of the glass.

Municipal Autonomous General Educational Institution

Secondary school No. 35

town Novomikhailovsky

municipality

Tuapse district

Entertaining experiences on the subject

"Chemistry in Nature"

Teacher:

Kozlenko

Alevtina Viktorovna

2015

Extraction of "gold".Lead acetate is dissolved in one flask with hot water, and potassium iodide is dissolved in the other. Both solutions are poured into a large flask, the mixture is allowed to cool and show beautiful golden scales floating in the solution.

Pb (CH 3 COO) 2 + 2KI \u003d PbI 2 + 2CH3COOK

Mineral "chameleon".3 ml of a saturated potassium permanganate solution and 1 ml of a 10% potassium hydroxide solution are poured into a test tube.

10-15 drops of sodium sulfite solution are added to the resulting mixture while shaking until a dark green color appears. When stirred, the color of the solution turns blue, then purple and finally raspberry.

The appearance of a dark green color is due to the formation of potassium manganate

K 2 MPO 4:

2KMpo 4 + 2KOH + Na 2 SO 3 \u003d 2K 2 MnO 4 + Na 2 SO 4 + H 2 O.

The change in the dark green color of the solution is due to the decomposition of potassium manganate under the influence of atmospheric oxygen:

4K 2 MnO 4 + O 2 + 2H 2 O \u003d 4KMpO 4 + 4KON.

The transformation of red phosphorus into white.A glass rod is lowered into a dry test tube and red phosphorus is placed in the amount of half a pea. The bottom of the test tube is very hot. First, there is white smoke. With further heating, yellowish droplets of white phosphorus appear on the cold inner walls of the test tube. It is also deposited on a glass rod. After stopping the heating of the test tube, the glass rod is removed. White phosphorus ignites on it. With the end of a glass rod, white phosphorus is also removed from the inner walls of the test tube. In the air there is a second flash.

The experiment is carried out only by the teacher.

Pharaoh snakes. For the experiment, a salt is prepared - mercury (II) thiocyanate by mixing a concentrated solution of mercury (II) nitrate with a 10% solution of potassium thiocyanate. The precipitate is filtered, washed with water and sticks are made 3-5 mm thick and 4 cm long. The sticks are dried on glass at room temperature. During the demonstration, sticks are placed on a demonstration table and set on fire. As a result of the decomposition of mercury (II) thiocyanate, products are released that take the form of a writhing snake. Its volume is many times greater than the original volume of salt:

Hg (NO 3) 2 + 2KCNS \u003d Hg (CNS) 2 + 2KNO 3

2Hg (CNS| 2 = 2HgS + CS 2 + C 3 N 4 .

Dark gray snake.Sand is poured into a crystallizer or onto a glass plate and impregnated with alcohol. A hole is made in the center of the cone and a mixture of 2 g of baking soda and 13 g of powdered sugar is placed there. Burn alcohol. Caxap turns into caramel, and soda decomposes with the release of carbon monoxide (IV). A thick dark gray "snake" crawls out of the sand. The longer the alcohol burns, the longer the "snake".

"Chemical algae». A solution of silicate glue (sodium silicate) diluted with an equal volume of water is poured into a glass. Crystals of calcium chloride, manganese (II), cobalt (II), nickel (II) and other metals are thrown to the bottom of the glass. After some time, crystals of the corresponding sparingly soluble silicates begin to grow in the glass, resembling algae.

Burning snow. Together with snow, 1-2 pieces of calcium carbide are placed in a jar. After that, a burning splinter is brought to the jar. The snow flares up and burns with a smoky flame. The reaction takes place between calcium carbide and water:

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

The escaping gas - acetylene burns:

2C 2 H 2 + 5O 2 \u003d 4CO 2 + 2H 2 O.

"Buran" in a glass.Pour 5 g of benzoic acid into a 500 ml beaker and put a sprig of pine. Close the glass with a porcelain cup with cold water and heat it over an alcohol lamp. The acid first melts, then turns into steam, and the glass is filled with white "snow" that covers the twig.

Secondary school No. 35

Novomikhailovsky settlement

municipality

Tuapse district

Entertaining experiences on the subject

"Chemistry in agriculture"

Teacher:

Kozlenko

Alevtina Viktorovna

2015

Different ways to get "milk".Solutions are prepared for the experiment: sodium chloride and silver nitrate; barium chloride and sodium sulfate; calcium chloride and sodium carbonate. Pour these solutions into separate beakers. In each of them, “milk” is formed - insoluble white salts:

NaCI + AgNO 3 \u003d AgCI ↓ + NaNO 3;

Na 2 SO 4 + ВаСI 2 \u003d BaSO 4 ↓ + 2NaCI;

Na 2 CO 3 + CaCI 2 \u003d CaCO 3 ↓ + 2NaCI.

Turning milk into water.An excess of hydrochloric acid is added to a white precipitate obtained by pouring solutions of calcium chloride and sodium carbonate. The liquid boils and becomes colorless and

transparent:

CaCl 2 + Na 2 CO 3 \u003d CaCO 3 ↓ + 2NaCl;

CaCO3↓ + 2HCI = CaCI 2 + H 2 O + CO 2.

original egg. An egg is dipped into a glass jar with a dilute solution of hydrochloric acid. After 2-3 minutes, the egg is covered with gas bubbles and floats to the surface of the liquid. The gas bubbles break off and the egg sinks to the bottom again. So, diving and rising, the egg moves until the shell dissolves.

Municipal educational institution

Secondary school No. 35

Novomikhailovsky settlement

municipality

Tuapse district

extracurricular activity

"Interesting questions about chemistry"

Teacher:

Kozlenko

Alevtina Viktorovna

2015

Quiz.

1. Name the ten most common elements in the earth's crust.

2. What chemical element was discovered earlier on the Sun than on Earth?

3. What rare metal is found in some gemstones?

4. What is helium air?

5. What metals and alloys melt in hot water?

6. What refractory metals do you know?

7. What is heavy water?

8. Name the elements that make up the human body.

9. Name the heaviest gas, liquid and solid.

10. How many elements are used in the manufacture of a car?

11. What chemical elements enter the plant from air, water, soil?

12. What salts of sulfuric and hydrochloric acids are used to protect plants from pests and diseases?

13. What kind of molten metal can freeze water /?

14. Is drinking clean water good for a person?

15. Who was the first to determine the quantitative chemical composition of water by methods of synthesis and analysis?

16 . What gas is in the solid state at a temperature - 2>252 °C combines with an explosion with liquid hydrogen?

17. What element is the basis of the entire mineral world of the Nanki planet?

18. Which compound of chlorine and mercury is a strong poison?

19. The names of what elements are associated with radioactive processes?

Answers:

1. The following elements are most common in the earth's crust: oxygen, silicon, aluminum, iron, calcium, sodium, magnesium, potassium, hydrogen, titanium. These elements occupy approximately 96.4% of the mass of the earth's crust; for all other elements, only 3.5% of the mass of the earth's crust remains.

2. Helium was first discovered on the Sun, and only a quarter of a century later it was found on Earth.

3. The metal beryllium is found in nature as an integral part of precious stones (beryl, aquamarine, alexandrite, etc.).

4. This is the name of artificial air, which includes approximately 20% oxygen and 80% helium.

5. The following metals melt in hot water: cesium (+28.5 °С), gallium (+ 29.75 °С), rubidium (+ 39 °С), potassium (+63 °С). Wood's alloy (50% Bi, 25% Pb, 12.5% Sn, 12.5% Cd) melts at +60.5°C.

6. The most refractory metals such as: tungsten (3370 ° C), rhenium (3160 ° C), tantalum (3000 ° C), osmium (2700 ° C), molybdenum (2620 ° C), niobium (2415 ° C).

7. Heavy water is the compound of the hydrogen isotope of deuterium with oxygen D 2 A. There is a small amount of heavy water in ordinary water (1 part by weight in 5000 parts by weight).

8. The composition of the human body includes more than 20 elements: oxygen (65.04%), carbon (18.25%), hydrogen (10.05%), nitrogen (2.65%), calcium (1.4%) , phosphorus (0.84%), potassium (0.27%), chlorine (0.21%), sulfur (0.21%) and

others

9. The heaviest gas taken under normal conditions is tungsten hexafluoride WF 6 , the heaviest liquid is mercury, the heaviest solid is osmium metal Os.

10. Approximately 50 chemical elements are used in the manufacture of a car, which are part of 250 different substances and materials.

11. Carbon, nitrogen, oxygen enter the plant from the air. Hydrogen and oxygen from water. All other elements enter the plant from the soil.

12. Copper and iron sulfates, barium and zinc chlorides are used to protect plants from pests and diseases.

13. You can freeze water with mercury, it melts at a temperature of 39 ° C.

14. Chemists consider distilled water to be relatively pure water. But it is harmful to the body, becauseit does not contain useful salts and gases. It flushes out the salts contained in the cell sap from the cells of the stomach.

15. The quantitative chemical composition of water, first by the method of synthesis, and then by analysis, was determined by Lavoisier.

16. Fluorine is a very strong oxidizing agent. In the solid state, it combines with liquid hydrogen at a temperature of -252 °C.

17. Silicon makes up 27.6% of the earth's crust and is the main element in the kingdom of minerals and rocks, which are exclusively composed of silicon compounds.

18. A strong poison is the combination of chlorine with mercury - sublimate. In medicine, sublimate is used as a disinfectant (1:1000).

19. The names of such elements are associated with radioactive processes: astatine, radium, radon, actinium, protactinium.

Do you know that...

The production of 1 ton of building bricks requires 1-2 m 3 water, and for the production of 1 ton of nitrogen fertilizers and 1 ton of capron - respectively 600, 2500 m 3 .

The layer of the atmosphere at an altitude of 10 to 50 km is called the ozonosphere. The total amount of ozone gas is small; at normal pressure and temperature 0 ° C, it would be distributed over the earth's surface in a thin layer of 2-3 mm. The ozone of the upper layers of the atmosphere absorbs most of the ultraviolet radiation that the Sun sends out and protects all living things from its harmful effects.

Polycarbonate is a polymer that has interesting features. It can be hard like metal, elastic like silk, transparent like crystal, or dyed in different colors. The polymer can be molded. It does not burn, retains its properties at temperatures from +135 to -150 °C.

Ozone is toxic. In low concentrations (during a thunderstorm), the smell of ozone is pleasant and refreshing. At a concentration in the air of more than 1%, its smell is extremely unpleasant and it is impossible to breathe it.

A salt crystal with slow crystallization can reach a size of more than half a meter.

Pure iron is found on Earth only in the form of meteorites.

Burning magnesium cannot be extinguished with carbon dioxide, as it interacts with it and continues to burn due to the released oxygen.

The most refractory metal is tungsten (t pl 3410 ° C), and the most fusible metal is cesium (t pl 28.5 °С).

The largest gold nugget found in the Urals in 1837 weighed about 37 kg. A gold nugget of 108 kg was found in California, and 250 kg in Australia.

Beryllium is called the metal of indefatigability, because the springs made from its alloy can withstand up to 20 billion load cycles (they are almost eternal).

CURIOUS FIGURES AND FACTS

Freon substitutes. Freons and other synthetic substances containing chlorine and fluorine are known to destroy the ozone layer of the atmosphere. Soviet scientists found a replacement for freon - hydrocarbon propylanes (compounds of propane and butane), harmless to the atmospheric layer. By 1995, the chemical industry will produce 1 billion aerosols.

TU-104 and plastics. The TU-104 aircraft has 120,000 parts made of organic glass, other plastics and their various combinations with other materials.

Nitrogen and lightning. About 100 lightning strikes every second are one of the sources of nitrogen compounds. In this case, the following processes take place:

N 2 + O 2 \u003d 2NO

2NO+O 2 \u003d 2NO 2

2NO 2 + H 2 O + 1 / 2O 2 \u003d 2HNO 3

Thus, nitrate ions enter the soil, which are absorbed by plants.

Methane and warming. The methane content in the lower layers of the atmosphere (troposphere) averaged 0.0152 ppm 10 years ago. and was relatively constant. Recently, there has been a systematic increase in its concentration. An increase in the methane content in the troposphere contributes to an increase in the greenhouse effect, since methane molecules absorb infrared radiation.

Ashes in sea water. In the water of the seas and oceans there are dissolved salts of gold. Calculations show that the water of all seas and oceans contains about 8 billion tons of gold. Scientists are looking for the most profitable ways to extract gold from sea water. 1 ton of sea water contains 0.01-0.05 mg of gold.

"White Soot" . In addition to the usual, well-known black soot, there is also “white soot”. Gak is a powder of amorphous silicon dioxide, which is used as a filler for rubber in the manufacture of rubber from it.

Threat from trace elements. The active circulation of microelements accumulating in natural environments creates, according to experts, a serious threat to the health of modern man and future generations. Their sources are millions of tons of annually burned fuel, blast furnace production, non-ferrous metallurgy, mineral fertilizers applied to the soil, etc.

Transparent rubber.In the manufacture of rubber from rubber, zinc oxide is used (it speeds up the vulcanization process of rubber). If zinc peroxide is added to rubber instead of zinc oxide, then the rubber is transparent. Through a layer of such rubber 2 cm thick, you can freely read a book.

Oil is more valuable than gold.Rose oil is required to make many types of perfume. It is a mixture of aromatic substances extracted from rose petals. To obtain 1 kg of this oil, 4-5 tons of petals must be collected and subjected to chemical treatment. Rose oil is filtered three times more expensive than gold.

Iron is within us.The body of an adult contains 3.5 g of iron. This is very little compared, for example, with calcium, which is more than 1 kg in the body. But if we compare not the total content of these elements, but their concentration only in the blood, then there is five times more iron than calcium. The main mass of iron, which is part of the body (2.45 g), is concentrated in blood erythrocytes. Iron is found in the muscle protein myoglobin and in many enzymes. 1% of iron constantly circulates in plasma - the liquid part of the blood. The main "depot" of iron is the liver: here, an adult male can store up to 1 g of iron. Between all tissues and organs containing iron, there is a constant exchange. About 10% of iron is brought into the bone marrow by the blood. It is part of the pigment that colors the hair.

Phosphorus - the element of life and thought. In animals, phosphorus is concentrated mainly in the skeleton, muscles and nervous tissue. The human body contains on average about 1.5 kg of phosphorus. Of this mass, 1.4 kg is in the bones, about 130 g is in the muscles, and 12 g is in the nerves and brain. Almost all physiological processes occurring in our body are associated with the transformation of organophosphorus substances.

asphalt lake. On the island of Trinidad in the Lesser Antilles group, there is a lake filled not with water, but with frozen asphalt. Its area is 45 hectares, and the depth reaches 90 m. It is believed that the lake was formed in the crater of a volcano, into which oil penetrated through underground cracks. Millions of tons of asphalt have already been extracted from it.

Microalloying.Microalloying is one of the central problems of modern materials science. By introducing small amounts (approximately 0.01%) of certain elements, it is possible to noticeably change the properties of the alloys. This is due to segregation, i.e., the formation of an excess concentration of alloying elements on structural defects.

Types of coal. "Colorless Coal"- this is gas, "yellow coal" - solar energy, "green coal" - vegetable fuel, "blue coal" - the energy of the ebbs and flows of the seas, "blue coal" - the driving force of the wind, "red coal" - the energy of volcanoes.

Native aluminium.Recent discoveries of native metallic aluminum have raised the question of how it was formed. According to scientists, in natural melts under the influence of electrotelluric currents (electric currents flowing in the earth's crust), aluminum is reduced electrochemically.

Plastic nail.Plastic masses - polycarbonates were also suitable for the manufacture of nails. Nails from them are freely driven into the board and do notrust, in many cases perfectly replacing iron nails.

Sulfuric acid in nature. Sulfuric acid is obtained fromchemical plants. It turned out that it is formed in nature, primarily in volcanoes. For example, in the waters of the Rio Negro, which originates from the volcano Puracho in South America, in the crater of which sulfur is formed, contains up to0.1% sulfuric acid. The river daily carries into the sea up to 20 liters of "volcanic" sulfuric acid. In the USSR, sulfuric acid was discovered by academician Fersman in sulfur deposits in the Karakum desert.

Fun chemistry games

Who is faster and more?The teacher invites the participants of the game to write the names of elements ending in the same letter, for example, in “n” (argon, krypton, xenon, lanthanum, molybdenum, neon, radon, etc.). The game can be made more difficult by offering to find these elements in the table

D. I. Mendeleev and indicate which of them are metals and which non-metals.

Make up the names of the elements.The teacher calls the student to the blackboard and asks him to write down a series of syllables. The rest of the students write them in their notebooks. Task: in 3 minutes, make possible names of elements from the recorded syllables. For example, from the syllables "se, tiy, diy, ra, lion, li" you can compose the words: "lithium, sulfur, radium, selenium."

Drawing up reaction equations.“Who can quickly write equations for reactions, for example, between a metal and oxygen? - asks the teacher, referring to the participants in the game. - Write down the equation for the oxidation of aluminum. Whoever writes the equation first, let him raise his hand.”

Who knows more?The teacher closes the table with a strip of paper

D. I. Mendeleev some group of elements (or period) and in turn invites the teams to name and write the signs of the elements of a closed group (or period). The winner is the student who names the most chemical elements and correctly writes their signs.

The meaning of the names of elements in translation from a foreign language.What does the word "bromine" mean in Greek? You can play the same game and find out by the participants the meaning of the names of the elements translated from Latin (for example, ruthenium, tellurium, gallium, hafnium, lutetium, holmium, etc.).

Name the formula. The teacher names some compound, for example, magnesium hydroxide. The players, in whose hands are tablets with formulas, run out, holding a tablet with the corresponding formula in their hands.

Charades, puzzles,

chainwords, crosswords.

1 . The first four letters of the name of the famous Greek philosopher "denote the word" people "in Greek without the last letter, the last four are an island in the Mediterranean Sea; in general - the name of the Greek philosopher, founder of the atomistic theory.(Demos, Crete - Democritus.)

2. The first syllable of the name of a chemical element is also the first of the name of one of the elements of the platinum group; in general, it is the metal for which Marie Skłodowska-Curie won the Nobel Prize.(Radon, rhodium - radium.)

3. The first syllable of the name of the chemical element is also the first of the name of the "lunar element"; the second is the first in the name of the metal discovered by M. Sklodowska-Curie; in general it is (in alchemical language) "the gall of the god Vulcan".(Selenium, radium - sulfur.)

4. The first syllable of the name is also the first syllable of the name of an asphyxiant gas obtained by the synthesis of carbon monoxide (II) and chlorine; the second syllable is the first in the name of the solution of formaldehyde in water; in general, it is a chemical element, about which A.E. Fersman wrote that it is an element of life and thought.(Phosgene, formalin- phosphorus.)

My personal experience of teaching chemistry has shown that such a science as chemistry is very difficult to study without any initial knowledge and practice. Schoolchildren very often run this subject. I personally observed how a student of the 8th grade at the word "chemistry" began to frown, as if he had eaten a lemon.

Later it turned out that because of dislike and misunderstanding of the subject, he skipped school in secret from his parents. Of course, the school curriculum is designed in such a way that the teacher must give a lot of theory at the first chemistry lessons. Practice, as it were, fades into the background precisely at the moment when the student cannot yet independently realize whether he needs this subject in the future. This is primarily due to the laboratory equipment of schools. In big cities, things are better now with reagents and instruments. As for the province, as well as 10 years ago, and at present, many schools do not have the opportunity to conduct laboratory classes. But the process of studying and fascination with chemistry, as well as with other natural sciences, usually begins with experiments. And it is no coincidence. Many famous chemists, such as Lomonosov, Mendeleev, Paracelsus, Robert Boyle, Pierre Curie and Maria Sklodowska-Curie (schoolchildren also study all these researchers in physics classes) have already started experimenting since childhood. The great discoveries of these great people were made in home chemical laboratories, since chemistry classes at institutes were available only to wealthy people.

And, of course, the most important thing is to interest the child and convey to him that chemistry surrounds us everywhere, so the process of studying it can be very exciting. This is where home chemistry experiments come in handy. Observing such experiments, one can further look for an explanation of why things happen this way and not otherwise. And when a young researcher comes across such concepts at school lessons, the teacher’s explanations will be more understandable to him, since he will already have his own experience in conducting home chemical experiments and the knowledge gained.

It is very important to start science studies with the usual observations and real life examples that you think will be the best for your child. Here is some of them. Water is a chemical substance consisting of two elements, as well as gases dissolved in it. Man also contains water. We know that where there is no water, there is no life. A person can live without food for about a month, and without water - only a few days.

River sand is nothing but silicon oxide, and also the main raw material for glass production.

A person himself does not suspect it and carries out chemical reactions every second. The air we breathe is a mixture of gases - chemicals. In the process of exhalation, another complex substance is released - carbon dioxide. We can say that we ourselves are a chemical laboratory. You can explain to the child that washing hands with soap is also a chemical process of water and soap.

An older child who, for example, has already begun to study chemistry at school, can be explained that almost all elements of the periodic system of D. I. Mendeleev can be found in the human body. In a living organism, not only all chemical elements are present, but each of them performs some biological function.

Chemistry is also medicines, without which at present many people cannot live even a day.

Plants also contain the chemical chlorophyll, which gives the leaf its green color.

Cooking is a complex chemical process. Here you can give an example of how the dough rises when yeast is added.

One of the options for getting a child interested in chemistry is to take an individual outstanding researcher and read the story of his life or watch an educational film about him (films about D.I. Mendeleev, Paracelsus, M.V. Lomonosov, Butlerov are now available).

Many believe that real chemistry is harmful substances, it is dangerous to experiment with them, especially at home. There are many very exciting experiences that you can do with your child without harming your health. And these home chemical experiments will be no less exciting and instructive than those that come with explosions, pungent odors and puffs of smoke.

Some parents are also afraid to conduct chemical experiments at home because of their complexity or the lack of the necessary equipment and reagents. It turns out that you can get by with improvised means and those substances that every housewife has in the kitchen. You can buy them at your nearest household store or pharmacy. Test tubes for home chemical experiments can be replaced with pill bottles. For storage of reagents, you can use glass jars, for example, from baby food or mayonnaise.

It is worth remembering that the dishes with reagents must have a label with the inscription and be tightly closed. Sometimes the tubes need to be heated. In order not to hold it in your hands when heated and not get burned, you can build such a device using a clothespin or a piece of wire.

It is also necessary to allocate several steel and wooden spoons for mixing.

You can make a stand for holding test tubes yourself by drilling through holes in the bar.

To filter the resulting substances, you will need a paper filter. It is very easy to make it according to the diagram given here.

For children who do not yet go to school or are studying in elementary grades, setting up home chemical experiments with their parents will be a kind of game. Most likely, such a young researcher will not yet be able to explain some individual laws and reactions. However, it is possible that just such an empirical way of discovering the surrounding world, nature, man, plants through experiments will lay the foundation for the study of natural sciences in the future. You can even arrange original competitions in the family - who will have the most successful experience and then demonstrate them at family holidays.

Regardless of the age of the child and his ability to read and write, I advise you to have a laboratory journal in which you can record experiments or sketch. A real chemist must write down a work plan, a list of reagents, sketches of instruments and describes the progress of work.

When you and your child just begin to study this science of substances and conduct home chemical experiments, the first thing to remember is safety.

To do this, follow the following safety rules:

2. It is better to allocate a separate table for conducting chemical experiments at home. If you do not have a separate table at home, then it is better to conduct experiments on a steel or iron tray or pallet.

3. It is necessary to get thin and thick gloves (they are sold in a pharmacy or hardware store).

4. For chemical experiments, it is best to buy a lab coat, but you can also use a thick apron instead of a dressing gown.

5. Laboratory glassware should not be used for food.

6. In home chemical experiments, there should be no cruelty to animals and violation of the ecological system. Acidic chemical waste should be neutralized with soda, and alkaline with acetic acid.

7. If you want to check the smell of a gas, liquid or reagent, never bring the vessel directly to your face, but, holding it at a certain distance, direct, waving your hand, the air above the vessel towards you and at the same time smell the air.

8. Always use small amounts of reagents in home experiments. Avoid leaving reagents in a container without an appropriate inscription (label) on the bottle, from which it should be clear what is in the bottle.

The study of chemistry should begin with simple chemical experiments at home, allowing the child to master the basic concepts. A series of experiments 1-3 allow you to get acquainted with the basic aggregate states of substances and the properties of water. To begin with, you can show a preschooler how sugar and salt dissolve in water, accompanying this with an explanation that water is a universal solvent and is a liquid. Sugar or salt are solids that dissolve in liquids.

Experience number 1 "Because - without water and neither here nor there"

Water is a liquid chemical substance composed of two elements as well as gases dissolved in it. Man also contains water. We know that where there is no water, there is no life. A person can live without food for about a month, and without water - only a few days.

Reagents and equipment: 2 test tubes, soda, citric acid, water

Experiment: Take two test tubes. Pour in equal amounts of soda and citric acid. Then pour water into one of the test tubes, and not into the other. In a test tube in which water was poured, carbon dioxide began to be released. In a test tube without water - nothing has changed

Discussion: This experiment explains the fact that many reactions and processes in living organisms are impossible without water, and water also accelerates many chemical reactions. Schoolchildren can be explained that an exchange reaction has taken place, as a result of which carbon dioxide has been released.

Experience number 2 "What is dissolved in tap water"

Reagents and equipment: clear glass, tap water

Experiment: Pour tap water into a transparent glass and put it in a warm place for an hour. After an hour, you will see settled bubbles on the walls of the glass.

Discussion: Bubbles are nothing but gases dissolved in water. Gases dissolve better in cold water. As soon as the water becomes warm, the gases cease to dissolve and settle on the walls. A similar home chemical experiment also makes it possible to acquaint the child with the gaseous state of matter.

Experience No. 3 “What is dissolved in mineral water or water is a universal solvent”

Reagents and equipment: test tube, mineral water, candle, magnifying glass

Experiment: Pour mineral water into a test tube and slowly evaporate it over a candle flame (the experiment can be done on the stove in a saucepan, but the crystals will be less visible). As the water evaporates, small crystals will remain on the walls of the test tube, all of them of different shapes.

Discussion: Crystals are salts dissolved in mineral water. They have a different shape and size, since each crystal has its own chemical formula. With a child who has already begun to study chemistry at school, you can read the label on mineral water, which indicates its composition and write the formulas of the compounds contained in mineral water.

Experiment No. 4 "Filtration of water mixed with sand"

Reagents and equipment: 2 test tubes, funnel, paper filter, water, river sand

Experiment: Pour water into a test tube and dip a little river sand into it, mix. Then, according to the scheme described above, make a filter out of paper. Insert a dry, clean test tube into a rack. Slowly pour the sand/water mixture through a filter paper funnel. River sand will remain on the filter, and you will get clean water in a tripod tube.

Discussion: Chemical experience allows us to show that there are substances that do not dissolve in water, for example, river sand. The experience also introduces one of the methods of cleaning mixtures of substances from impurities. Here you can introduce the concepts of pure substances and mixtures, which are given in the 8th grade chemistry textbook. In this case, the mixture is sand with water, the pure substance is the filtrate, and river sand is the sediment.

The filtration process (described in Grade 8) is used here to separate a mixture of water and sand. To diversify the study of this process, you can delve a little into the history of drinking water purification.

Filtration processes were used as early as the 8th and 7th centuries BC. in the state of Urartu (now it is the territory of Armenia) for the purification of drinking water. Its inhabitants carried out the construction of a water supply system with the use of filters. Thick cloth and charcoal were used as filters. Similar systems of intertwined drainpipes, clay canals, equipped with filters were also on the territory of the ancient Nile among the ancient Egyptians, Greeks and Romans. Water was passed through such a filter repeatedly through such a filter several times, eventually many times, ultimately achieving the best water quality.

One of the most interesting experiments is growing crystals. The experience is very clear and gives an idea of many chemical and physical concepts.

Experience number 5 "Grow sugar crystals"

Reagents and equipment: two glasses of water; sugar - five glasses; wooden skewers; thin paper; pot; transparent cups; food coloring (the proportions of sugar and water can be reduced).

Experiment: The experiment should begin with the preparation of sugar syrup. We take a pan, pour 2 cups of water and 2.5 cups of sugar into it. We put on medium heat and, stirring, dissolve all the sugar. Pour the remaining 2.5 cups of sugar into the resulting syrup and cook until completely dissolved.

Now let's prepare the embryos of crystals - sticks. Scatter a small amount of sugar on a piece of paper, then dip the stick in the resulting syrup, and roll it in sugar.

We take the pieces of paper and pierce a hole in the middle with a skewer so that the piece of paper fits snugly against the skewer.

Then we pour the hot syrup into transparent glasses (it is important that the glasses are transparent - this way the process of crystal ripening will be more exciting and visual). The syrup must be hot or the crystals will not grow.

You can make colored sugar crystals. To do this, add a little food coloring to the resulting hot syrup and stir it.

The crystals will grow in different ways, some quickly and some may take longer. At the end of the experiment, the child can eat the resulting lollipops if he is not allergic to sweets.

If you do not have wooden skewers, then you can experiment with ordinary threads.

Discussion: A crystal is a solid state of matter. It has a certain shape and a certain number of faces due to the arrangement of its atoms. Crystalline substances are substances whose atoms are arranged regularly, so that they form a regular three-dimensional lattice, called a crystal. Crystals of a number of chemical elements and their compounds have remarkable mechanical, electrical, magnetic and optical properties. For example, diamond is a natural crystal and the hardest and rarest mineral. Due to its exceptional hardness, diamond plays a huge role in technology. Diamond saws cut stones. There are three ways to form crystals: crystallization from a melt, from a solution, and from a gas phase. An example of crystallization from a melt is the formation of ice from water (after all, water is molten ice). An example of crystallization from solution in nature is the precipitation of hundreds of millions of tons of salt from sea water. In this case, when growing crystals at home, we are dealing with the most common methods of artificial growing - crystallization from a solution. Sugar crystals grow from a saturated solution by slowly evaporating the solvent - water, or by slowly lowering the temperature.

The following experience allows you to get at home one of the most useful crystalline products for humans - crystalline iodine. Before conducting the experiment, I advise you to watch with your child a short film “The life of wonderful ideas. Smart iodine. The film gives an idea of the benefits of iodine and the unusual story of its discovery, which will be remembered by the young researcher for a long time. And it is interesting because the discoverer of iodine was an ordinary cat.

The French scientist Bernard Courtois during the years of the Napoleonic Wars noticed that in the products obtained from the ashes of seaweed, which were thrown onto the coast of France, there is some substance that corrodes iron and copper vessels. But neither Courtois himself nor his assistants knew how to isolate this substance from the ashes of algae. Chance helped speed up the discovery.

At his small saltpeter plant in Dijon, Courtois was going to conduct several experiments. There were vessels on the table, one of which contained an alcoholic tincture of seaweed, and the other a mixture of sulfuric acid and iron. On the shoulders of the scientist sat his beloved cat.

There was a knock on the door, and the frightened cat jumped down and ran away, brushing the flasks on the table with its tail. The vessels broke, the contents mixed, and suddenly a violent chemical reaction began. When a small cloud of vapors and gases settled, the surprised scientist saw some kind of crystalline coating on the objects and debris. Courtois began to explore it. Crystals to anyone before this unknown substance were called "iodine".

So a new element was discovered, and Bernard Courtois's domestic cat went down in history.

Experience No. 6 "Obtaining iodine crystals"

Reagents and equipment: tincture of pharmaceutical iodine, water, a glass or a cylinder, a napkin.

Experiment: We mix water with tincture of iodine in the proportion: 10 ml of iodine and 10 ml of water. And put everything in the refrigerator for 3 hours. During cooling, the iodine will precipitate at the bottom of the glass. We drain the liquid, take out the iodine precipitate and put it on a napkin. Squeeze with napkins until the iodine begins to crumble.

Discussion: This chemical experiment is called extraction or extraction of one component from another. In this case, the water extracts the iodine from the spirit lamp solution. Thus, the young researcher will repeat the experience of the cat Courtois without smoke and beating dishes.

Your child will already learn about the benefits of iodine for disinfecting wounds from the movie. Thus, you show that there is an inextricable link between chemistry and medicine. However, it turns out that iodine can be used as an indicator or analyzer of the content of another useful substance - starch. The following experience will introduce the young experimenter to a separate very useful chemistry - analytical.

Experience No. 7 "Iodine-indicator of starch content"

Reagents and equipment: fresh potatoes, pieces of banana, apple, bread, a glass of diluted starch, a glass of diluted iodine, a pipette.

Experiment: We cut the potatoes into two parts and drip diluted iodine on it - the potatoes turn blue. Then we drip a few drops of iodine into a glass of diluted starch. The liquid also turns blue.

We drip with a pipette iodine dissolved in water on an apple, banana, bread, in turn.

Watching:

The apple didn't turn blue at all. Banana - slightly blue. Bread - turned blue very much. This part of the experience shows the presence of starch in various foods.

Discussion: Starch, reacting with iodine, gives a blue color. This property gives us the ability to detect the presence of starch in various foods. Thus, iodine is, as it were, an indicator or analyzer of starch content.

As you know, starch can be converted into sugar, if you take an unripe apple and drop iodine, it will turn blue, since the apple is not yet ripe. As soon as the apple ripens, all the starch contained will turn into sugar and the apple does not turn blue at all when treated with iodine.

The following experience will be useful for children who have already started studying chemistry at school. It introduces concepts such as chemical reaction, compound reaction, and qualitative reaction.

Experiment No. 8 "Flame coloring or compound reaction"

Reagents and equipment: tweezers, table salt, spirit lamp

Experiment: Take with tweezers a few crystals of coarse salt table salt. Let's hold them over the flame of the burner. The flame will turn yellow.

Discussion: This experiment makes it possible to carry out a chemical combustion reaction, which is an example of a compound reaction. Due to the presence of sodium in the composition of table salt, during combustion, it reacts with oxygen. As a result, a new substance is formed - sodium oxide. The appearance of a yellow flame indicates that the reaction has passed. Such reactions are qualitative reactions to compounds containing sodium, that is, it can be used to determine whether sodium is present in a substance or not.

Not a single person, even the least bit familiar with the problems of modern education, will argue about the advantages of the Soviet system. However, it also had certain drawbacks, in particular, in the study of natural science subjects, the emphasis was often placed on providing a theoretical component, and practice was relegated to the background. However, any teacher will confirm that the best way to generate interest in these subjects in a child is to show some spectacular physical or chemical experience. This is especially important at the initial stage of studying such subjects and even long before that. In the second case, a special kit for chemical experiments, which can be used at home, can be a good help for parents. True, when purchasing such a gift, fathers and mothers should understand that they will also have to take part in classes, since such a “toy” in the hands of a child left unattended represents a certain danger.

What is a chemical experiment

First of all, you should understand what is at stake. In general, it is generally accepted that a chemical experiment is the manipulation of various organic and inorganic substances in order to establish their properties and reactions under various conditions. If we are talking about experiments that are carried out in order to arouse in the child the desire to explore the world around them, then they should be spectacular and at the same time simple. In addition, it is not recommended to choose options that require special security measures.

Where to begin

First of all, you can tell the child that everything that surrounds us, including his own body, consists of various substances that interact. As a result, various phenomena can be observed: both those to which people have long been accustomed and do not pay attention to them, and very unusual ones. In this case, rust, which is a consequence of the oxidation of metals, or smoke from a fire, which is a gas released during the combustion of various objects, can be cited as an example. Then you can start showing simple chemical experiments.

"Float Egg"

A very interesting experiment can be shown using an egg and an aqueous solution of hydrochloric acid. To carry it out, you need to take a glass decanter or a wide glass and pour a 5% solution of hydrochloric acid onto the bottom. Then you need to lower the egg into it and wait a while.

Soon, bubbles of carbon dioxide will appear on the surface of the egg shell due to the reaction of hydrochloric acid and calcium carbonate contained in the shell and lift the egg up. Having reached the surface, the gas bubbles will burst, and the "load" will again go to the bottom of the dish. The process of lifting and diving the egg will continue until all the eggshell has been dissolved in the hydrochloric acid.

"Secret Signs"

Interesting chemical experiments can be done with sulfuric acid. For example, with a cotton swab dipped in a 20% sulfuric acid solution, figures or letters are drawn on paper and wait for the liquid to dry. Then the sheet is ironed with a hot iron and black letters begin to appear. This experience will be even more spectacular if you hold the leaf over the flame of a candle, but this must be done very carefully, trying not to set fire to the paper.

"Fire Lettering"

The previous experience can be done differently. To do this, draw a contour of a figure or letter on a piece of paper with a pencil and prepare a composition consisting of 20 g of KNO 3 dissolved in 15 ml of hot water. Then, with a brush, saturate the paper along the pencil lines so that there are no gaps. As soon as the audience is ready, and the sheet is dry, you need to bring a burning splinter to the inscription at only one point. Immediately a spark will appear, which will “run” along the outline of the drawing until it reaches the end of the line.

Surely young viewers will be interested in why such an effect is achieved. Explain that when heated, potassium nitrate turns into another substance, potassium nitrite, and releases oxygen, which supports combustion.

"Fireproof Handkerchief"

Children will certainly be interested in the experience with "fireproof" fabric. To demonstrate it, 10 g of silicate glue is dissolved in 100 ml of water and a piece of cloth or handkerchief is moistened with the resulting liquid. Then it is squeezed out and, using tweezers, immersed in a container with acetone or gasoline. Immediately set fire to the fabric with a splinter and watch how the flame "devours" the handkerchief, but it remains intact.

"Blue Bouquet"

Simple chemical experiments can be very spectacular. We invite you to surprise the viewer by using paper flowers, the petals of which should be smeared with natural starch glue. Then the bouquet should be placed in a jar, a few drops of iodine alcohol tincture should be put on the bottom and the lid should be tightly closed. In a few minutes, a "miracle" will happen: the flowers will turn blue, because the iodine vapor will cause the starch to change its color.

"Christmas decorations"

An original chemical experiment, as a result of which you will have beautiful decorations for a mini-Christmas tree, will turn out if you use a saturated solution (1:12) of potassium alum KAl (SO 4) 2 with the addition of copper sulfate CuSO 4 (1: 5).

First you need to make a frame of a figurine from a wire, wrap it with white woolen threads and lower them into a pre-prepared mixture. After a week or two, crystals will grow on the workpiece, which should be varnished so that they do not crumble.

"Volcanoes"

A very effective chemical experiment will turn out if you take a plate, plasticine, baking soda, table vinegar, red dye and dishwashing liquid. Next, you need to do the following:

divide a piece of plasticine into two parts;
roll one into a flat pancake, and fashion a hollow cone from the second, at the top of which you need to leave a hole;
put the cone on a plasticine base and connect it so that the "volcano" does not let water through;
put the structure on a tray;
pour "lava", consisting of 1 tbsp. l. baking soda and a few drops of liquid food coloring;
when the audience is ready, pour vinegar into the "vent" and watch the violent reaction, during which carbon dioxide is released, and red foam flows out of the volcano.

As you can see, home chemical experiments can be very diverse, and all of them will interest not only children, but also adults.