Chemical experiments for children at home. Interesting chemistry experiments you can do at home

How to interest a child in the knowledge of new substances and the properties of various objects and liquids? At home, you can arrange an impromptu chemical laboratory and conduct simple chemical experiments for children at home.

Transformations will be original and appropriate in honor of any festive event or in the most ordinary conditions to familiarize the child with the properties of different materials. Here are some simple magic tricks that are easy to do at home.

Chemical experiments using ink

Take a small container with water, preferably with transparent walls.

Dissolve a drop of ink or ink in it - the water will turn blue.

Add one pre-crushed activated charcoal tablet to the solution.

Then shake the container well and you will see that it will gradually become light, without a shade of paint. Charcoal powder has an absorbent property, and the water takes on its original color.

Trying to create clouds at home

Take a tall jar and pour some hot water (about 3 cm) into it. Prepare ice cubes in the freezer and place them on a flat baking sheet, which you place on top of the jar.

The hot air in the jar will cool, forming water vapor. The molecules of the condensate will begin to clump together in the form of a cloud. This transformation demonstrates the origin of clouds in nature when warm air is cooled. Why is it raining?

Drops of water on the ground are heated and rise up. There they cool and meet each other to form into clouds. Then the clouds also combine into heavy formations, and fall to the ground as precipitation. Watch a video of chemical experiments for children at home.

Feelings for hands at different water temperatures

You will need three deep bowls of water - cold, hot and room temperature.

The child should touch cold water with one hand and hot water with the other.

After a couple of minutes, both hands are placed in a vessel with water at room temperature. How does water feel to him? Is there a difference in perception temperature?

Water can soak up and stain the plant

For this beautiful transformation, you need a living plant or flower stem.

Place it in a glass of water dyed in any bright color (red, blue, yellow).

Gradually notice that the plant turns the same color.

This happens because the stem absorbs water and takes on its color. In the language of chemical phenomena, such a process is usually called osmosis or one-way diffusion.

You can make a fire extinguisher yourself at home

Necessary actions:

1. Let's take a candle.
2. It is necessary to light it, and place it in a jar so that it stands straight, and the flame does not reach its edges.
3. Carefully place a teaspoon of baking powder into the jar.
4. Then pour a little bit of vinegar into it.

Next, we look at the transformation - the white powder of baking powder will hiss, forming foam, and the candle will go out. This interaction of two substances provides the formation of carbon dioxide. It sinks to the bottom of the jar because it is heavy compared to other atmospheric gases.

The fire does not get access to oxygen and goes out. It is this principle that is laid down in the device of a fire extinguisher. All of them contain carbon dioxide, which extinguishes the flames of fire.

What else you need to read:

Oranges can float on water

If an orange is placed in a bowl of water, it will not sink. Clean it and dip it in water again - you will see it at the bottom. How did it happen?

The peel of an orange has air bubbles on which it floats on the water, almost like on an air mattress.

Checking the ability of eggs to float on water

We use water cans again. Put a couple of tablespoons of salt in one of them and stir until dissolved. Dip an egg in each of the jars. In salt water, it will be on the surface, and in normal water, it will sink to the bottom.

Helpful Hints

Children are always trying to find out something new every day and they always have a lot of questions.

They can explain some phenomena, or you can show how this or that thing, this or that phenomenon works.

In these experiments, children not only learn something new, but also learn create differentcrafts with which they can play further.

1. Experiments for children: lemon volcano

You will need:

2 lemons (for 1 volcano)

Baking soda

Food coloring or watercolors

Dishwashing liquid

Wooden stick or spoon (optional)

1. Cut off the bottom of the lemon so it can be placed on a flat surface.

2. On the reverse side, cut a piece of lemon as shown in the image.

* You can cut half a lemon and make an open volcano.

3. Take the second lemon, cut it in half and squeeze the juice out of it into a cup. This will be the backup lemon juice.

4. Place the first lemon (with the part cut out) on the tray and spoon "remember" the lemon inside to squeeze out some of the juice. It is important that the juice is inside the lemon.

5. Add food coloring or watercolor to the inside of the lemon, but do not stir.

6. Pour dishwashing liquid inside the lemon.

7. Add a full tablespoon of baking soda to the lemon. The reaction will start. With a stick or spoon, you can stir everything inside the lemon - the volcano will begin to foam.

8. To make the reaction last longer, you can gradually add more soda, dyes, soap and reserve lemon juice.

2. Home experiments for children: electric eels from chewing worms

You will need:

2 glasses

small capacity

4-6 chewable worms

3 tablespoons of baking soda

1/2 spoon of vinegar

1 cup water

Scissors, kitchen or clerical knife.

1. With scissors or a knife, cut lengthwise (just lengthwise - this will not be easy, but be patient) of each worm into 4 (or more) parts.

* The smaller the piece, the better.

* If scissors don't want to cut properly, try washing them with soap and water.

2. Mix water and baking soda in a glass.

3. Add pieces of worms to the solution of water and soda and stir.

4. Leave the worms in the solution for 10-15 minutes.

5. Using a fork, transfer the worm pieces to a small plate.

6. Pour half a spoon of vinegar into an empty glass and start putting worms in it one by one.

* The experiment can be repeated if the worms are washed with plain water. After a few attempts, your worms will begin to dissolve, and then you will have to cut a new batch.

3. Experiments and experiments: a rainbow on paper or how light is reflected on a flat surface

You will need:

bowl of water

Clear nail polish

Small pieces of black paper.

1. Add 1-2 drops of clear nail polish to a bowl of water. See how the varnish disperses through the water.

2. Quickly (after 10 seconds) dip a piece of black paper into the bowl. Take it out and let it dry on a paper towel.

3. After the paper has dried (it happens quickly) start turning the paper and look at the rainbow that is displayed on it.

* To better see the rainbow on paper, look at it under the sun's rays.

4. Experiments at home: a rain cloud in a jar

When small drops of water accumulate in a cloud, they become heavier and heavier. As a result, they will reach such a weight that they can no longer remain in the air and will begin to fall to the ground - this is how rain appears.

This phenomenon can be shown to children with simple materials.

You will need:

Shaving foam

Food coloring.

1. Fill the jar with water.

2. Apply shaving foam on top - it will be a cloud.

3. Let the child begin to drip food coloring onto the "cloud" until it starts to "rain" - drops of food coloring begin to fall to the bottom of the jar.

During the experiment, explain this phenomenon to the child.

You will need:

warm water

Sunflower oil

4 food coloring

1. Fill the jar 3/4 full with warm water.

2. Take a bowl and mix 3-4 tablespoons of oil and a few drops of food coloring in it. In this example, 1 drop of each of 4 dyes was used - red, yellow, blue and green.

3. Stir the dyes and oil with a fork.

4. Carefully pour the mixture into a jar of warm water.

5. Watch what happens - the food coloring will begin to slowly sink through the oil into the water, after which each drop will begin to disperse and mix with other drops.

* Food coloring dissolves in water, but not in oil, because. The density of oil is less than water (which is why it "floats" on water). A drop of dye is heavier than oil, so it will begin to sink until it reaches the water, where it begins to disperse and look like a small firework.

6. Interesting experiences: ina bowl in which colors merge

You will need:

- a printout of the wheel (or you can cut out your own wheel and draw all the colors of the rainbow on it)

Elastic band or thick thread

Glue stick

Scissors

A skewer or screwdriver (to make holes in the paper wheel).

1. Choose and print the two templates you want to use.

2. Take a piece of cardboard and use a glue stick to glue one template to the cardboard.

3. Cut out the glued circle from the cardboard.

4. Glue the second template to the back of the cardboard circle.

5. Use a skewer or screwdriver to make two holes in the circle.

6. Pass the thread through the holes and tie the ends into a knot.

Now you can spin your spinning top and watch how the colors merge on the circles.

7. Experiments for children at home: jellyfish in a jar

You will need:

Small transparent plastic bag

Transparent plastic bottle

Food coloring

Scissors.

1. Lay the plastic bag on a flat surface and smooth it out.

2. Cut off the bottom and handles of the bag.

3. Cut the bag lengthwise on the right and left so that you have two sheets of polyethylene. You will need one sheet.

4. Find the center of the plastic sheet and fold it like a ball to make a jellyfish head. Tie the thread around the "neck" of the jellyfish, but not too tight - you need to leave a small hole through which to pour water into the head of the jellyfish.

5. There is a head, now let's move on to the tentacles. Make cuts in the sheet - from the bottom to the head. You need about 8-10 tentacles.

6. Cut each tentacle into 3-4 smaller pieces.

7. Pour some water into the jellyfish's head, leaving room for air so the jellyfish can "float" in the bottle.

8. Fill the bottle with water and put your jellyfish in it.

9. Drop a couple of drops of blue or green food coloring.

* Close the lid tightly so that water does not spill out.

* Have the children turn the bottle over and watch the jellyfish swim in it.

8. Chemical experiments: magic crystals in a glass

You will need:

Glass cup or bowl

plastic bowl

1 cup Epsom salt (magnesium sulfate) - used in bath salts

1 cup hot water

Food coloring.

1. Pour Epsom salt into a bowl and add hot water. You can add a couple of drops of food coloring to the bowl.

2. Stir the contents of the bowl for 1-2 minutes. Most of the salt granules should dissolve.

3. Pour the solution into a glass or glass and place it in the freezer for 10-15 minutes. Don't worry, the solution isn't hot enough to crack the glass.

4. After freezing, move the solution to the main compartment of the refrigerator, preferably on the top shelf and leave overnight.

The growth of crystals will be noticeable only after a few hours, but it is better to wait out the night.

This is what the crystals look like the next day. Remember that crystals are very fragile. If you touch them, they are most likely to break or crumble immediately.

9. Experiments for children (video): soap cube

10. Chemical experiments for children (video): how to make a lava lamp with your own hands

Who loved chemistry labs at school? It is interesting, after all, it was to mix something with something and get a new substance. True, it didn’t always work out the way it was described in the textbook, but no one suffered about this, did they? The main thing is that something happens, and we saw it right in front of us.

If in real life you are not a chemist and do not face much more complex experiments every day at work, then these experiments that you can do at home will definitely amuse you, at least.

lava lamp

For experience you need:
– Transparent bottle or vase
— Water
- Sunflower oil
- Food coloring
- Several effervescent tablets "Suprastin"

Mix water with food coloring, pour sunflower oil. You don't need to mix, and you won't be able to. When a clear line between water and oil is visible, we throw a couple of Suprastin tablets into the container. Watching lava flows.

Since the density of oil is lower than that of water, it remains on the surface, with an effervescent tablet creating bubbles that carry water to the surface.

Elephant Toothpaste

For experience you need:
- Bottle
- small cup
— Water
- Dish detergent or liquid soap
- Hydrogen peroxide
- Fast acting nutritional yeast
- Food coloring

Mix liquid soap, hydrogen peroxide and food coloring in a bottle. In a separate cup, dilute the yeast with water and pour the resulting mixture into a bottle. We look at the eruption.

Yeast releases oxygen, which reacts with hydrogen and is pushed out. Due to the soap suds, a dense mass erupts from the bottle.

Hot Ice

For experience you need:
- container for heating
- Clear glass cup
- Plate
- 200 g baking soda
- 200 ml of acetic acid or 150 ml of its concentrate
- crystallized salt

We mix acetic acid and soda in a saucepan, wait until the mixture stops sizzling. We turn on the stove and evaporate excess moisture until an oily film appears on the surface. The resulting solution is poured into a clean container and cooled to room temperature. Then add a crystal of soda and watch how the water “freezes” and the container becomes hot.

Heated and mixed vinegar and soda form sodium acetate, which, when melted, becomes an aqueous solution of sodium acetate. When salt is added to it, it begins to crystallize and release heat.

rainbow in milk

For experience you need:
- Milk
- Plate
- Liquid food coloring in several colors
- cotton swab
— Detergent

Pour milk into a plate, drip dyes in several places. Wet a cotton swab in detergent, dip it into a bowl of milk. Let's see the rainbow.

In the liquid part there is a suspension of droplets of fat, which, when in contact with the detergent, split and rush from the inserted stick in all directions. A regular circle is formed due to surface tension.

Smoke without fire

For experience you need:
– Hydroperite
— Analgin
- Mortar and pestle (can be replaced with a ceramic cup and spoon)

The experiment is best done in a well-ventilated area.
We grind hydroperite tablets to a powder, we do the same with analgin. We mix the resulting powders, wait a bit, see what happens.

During the reaction, hydrogen sulfide, water and oxygen are formed. This leads to partial hydrolysis with the elimination of methylamine, which interacts with hydrogen sulfide, a suspension of its small crystals which resembles smoke.

pharaoh snake

For experience you need:
- Calcium gluconate
- Dry fuel
- Matches or lighter

We put several tablets of calcium gluconate on dry fuel, set fire to it. Let's look at the snakes.

Calcium gluconate decomposes when heated, which leads to an increase in the volume of the mixture.

non-newtonian fluid

For experience you need:

- mixing bowl
- 200 g corn starch
- 400 ml of water

Gradually add water to the starch and stir. Try to make the mixture homogeneous. Now try to roll the ball out of the resulting mass and hold it.

The so-called non-Newtonian fluid behaves like a solid body during fast interaction, and like a liquid during slow interaction.

Home chemists-scientists believe that the most useful property of detergents is the content of surfactants (surfactants). Surfactants significantly reduce the electrostatic voltage between the particles of substances and break down conglomerates. This feature makes it easier to clean clothes. In this article, chemical reactions that you can repeat with household chemicals, because with the help of surfactants you can not only remove dirt, but also conduct spectacular experiments.

Experience one: a foamy volcano in a jar

It is very easy to carry out this interesting experiment at home. For him you will need:

hydroperite, or (the higher the concentration of the solution, the more intense the reaction and the more effective the eruption of the "volcano"; therefore, it is better to buy tablets at a pharmacy and dilute them in a small volume in a ratio of 1/1 immediately before use (you will get a 50% solution - this is an excellent concentration);

gel detergent for dishes (prepare approximately 50 ml of an aqueous solution);

dye.

Now you need to get an effective catalyst - ammonia. Carefully and drop by drop add the ammonia liquid until completely dissolved.

copper sulfate crystals

Consider the formula:

CuSO₄ + 6NH₃ + 2H₂O = (OH)₂ (copper ammonia) + (NH₄)₂SO₄

Peroxide decomposition reaction:

2H₂O₂ → 2H₂O + O₂

We make a volcano: mix ammonia with a washing solution in a jar or wide-necked flask. Then quickly pour in the hydroperite solution. The "eruption" can be very strong - for safety reasons, it is better to substitute some kind of container under the volcano flask.

Experience two: the reaction of acid and sodium salts

Perhaps the most common compound that is in every home is baking soda. It reacts with acid, and the result is new salt, water and carbon dioxide. The latter can be detected by hissing and bubbles at the reaction site.

Experience three: "floating" soap bubbles

This is a very simple experience with baking soda. You will need:

• aquarium with a wide bottom;
• baking soda (150-200 grams);
• (6-9% solution);
• soap bubbles (to make your own, mix water, dish soap and glycerin)

On the bottom of the aquarium you need to evenly sprinkle soda and pour it with acetic acid. The result is carbon dioxide. It is heavier than air and therefore settles at the bottom of the glass box. To determine if there is CO₂ there, lower a lit match to the bottom - it will instantly go out in carbon dioxide.

NaHCO₃ + CH₃COOH → CH₃COONa + H₂O + CO₂

Now you need to blow bubbles into the container. They will slowly move along a horizontal line (the boundary of contact between carbon dioxide and air invisible to the eye, as if swimming in an aquarium).

Experience four: the reaction of soda and acid 2.0

For experience you will need:

• different types of non-hygroscopic food products (for example, gummies).
• a glass of diluted baking soda (one tablespoon);
• a glass with a solution of acetic or any other available acid (malic,).

Cut pieces of marmalade with a sharp knife into strips 1-3 cm long and place for processing in a glass with soda solution. Wait 10 minutes and then transfer the pieces to another beaker (with an acid solution).

Ribbons will be overgrown with bubbles of the resulting carbon dioxide and float to the top. On the surface, the bubbles will disappear, the lifting force of the gas will disappear, and the marmalade ribbons will sink, again overgrown with bubbles, and so on until the reagents in the container run out.

Experience five: properties of alkali and litmus paper

Most detergents contain sodium hydroxide, the most common alkali. It is possible to reveal its presence in a solution of a detergent in this elementary experiment. At home, a young enthusiast can easily conduct it on his own:

• take a strip of litmus paper;
• dissolve some liquid soap in water;
• dip the litmus into the soapy liquid;
• wait for the indicator to turn blue, which will indicate an alkaline reaction of the solution.

Click to find out what other experiments to determine the acidity of the environment can be carried out from improvised substances.

Experience six: colored explosions-stains in milk

The experience is based on the properties of the interaction of fats and surfactants. Fat molecules have a special, dual, structure: hydrophilic (interacting, dissociating with water) and hydrophobic (water-insoluble "tail" of a polyatomic compound) end of the molecule.

1. Pour milk into a wide container of small depth (“canvas”, on which a color explosion will be visible). Milk is a suspension, a suspension of fatty molecules in water.
2. With a pipette, add a few drops of water-soluble liquid dye to the milk container. You can add different dyes to different places of the container and make a multi-color explosion.
3. Then you need to moisten a cotton swab in liquid detergent and touch the surface of the milk. The white "canvas" of milk turns into a moving palette with paints that move in the liquid like spirals and twist into bizarre curves.

This phenomenon is based on the ability of surfactants to fragment (divide into sections) a film of fat molecules on the surface of a liquid. Fat molecules, repelled by their hydrophobic "tails", migrate in the milk suspension, and with them the partially undissolved paint.

Chemical experience of bromine with aluminum

If a few milliliters of bromine are placed in a test tube made of heat-resistant glass and a piece of aluminum foil is carefully lowered into it, then after a while (necessary for bromine to penetrate through the oxide film), a violent reaction will begin. From the heat released, aluminum melts and, in the form of a small fireball, rolls over the surface of bromine (the density of liquid aluminum is less than the density of bromine), rapidly decreasing in size. The test tube is filled with bromine vapor and white smoke, consisting of the smallest crystals of aluminum bromide:

2Al+3Br 2 → 2AlBr 3 .

It is also interesting to observe the reaction of aluminum with iodine. Mix in a porcelain cup a small amount of powdered iodine with aluminum powder. While the reaction is not noticeable: in the absence of water, it proceeds extremely slowly. Using a long pipette, drop a few drops of water on the mixture, which plays the role of an initiator, and the reaction will proceed vigorously - with the formation of a flame and the release of purple vapors of iodine.

Chemical experiments with gunpowder: how gunpowder explodes!

Gunpowder

Smoky, or black, gunpowder is a mixture of potassium nitrate (potassium nitrate - KNO 3), sulfur (S) and coal (C). It ignites at a temperature of about 300 °C. Gunpowder can also explode on impact. It consists of an oxidizing agent (nitrate) and a reducing agent (charcoal). Sulfur is also a reducing agent, but its main function is to bind potassium into a strong compound. During the combustion of gunpowder, the following reaction occurs:

2KNO 3 + ЗС + S → K 2 S + N 2 + 3СО 2,
- as a result of which a large volume of gaseous substances is released. The use of gunpowder in military affairs is connected with this: the gases formed during the explosion and expanding from the heat of the reaction push the bullet out of the gun barrel. It is easy to verify the formation of potassium sulfide by smelling the barrel of a gun. It smells of hydrogen sulfide - a product of the hydrolysis of potassium sulfide.

Chemical experiments with saltpeter: fiery inscription

Spectacular chemical experience can be carried out with potassium nitrate. Let me remind you that nitrates are complex substances - salts of nitric acid. In this case, we need potassium nitrate. Its chemical formula is KNO 3 . On a sheet of paper, draw a contour, a drawing (for greater effect, let the lines do not intersect!). Prepare a concentrated solution of potassium nitrate. For information: 20 g of KNO 3 is dissolved in 15 ml of hot water. Then, using a brush, we impregnate the paper along the drawn contour, while leaving no gaps or gaps. let the paper dry. Now you need to touch a burning splinter to some point on the contour. Immediately a "spark" will appear, which will slowly move along the contour of the picture until it closes it completely. Here's what happens: Potassium nitrate decomposes according to the equation:

2KNO 3 → 2 KNO 2 + O 2 .

Here KNO 2 +O 2 is a salt of nitrous acid. From the released oxygen, the paper chars and burns. For greater effect, the experiment can be carried out in a dark room.

Chemical experience of dissolving glass in hydrofluoric acid

Glass dissolves
in hydrofluoric acid

Indeed, glass dissolves easily. Glass is a very viscous liquid. The fact that glass can dissolve can be verified by performing the following chemical reaction. Hydrofluoric acid is an acid formed by dissolving hydrogen fluoride (HF) in water. It is also called hydrofluoric acid. For greater clarity, let's take a thin speckle, on which we attach a weight. We lower the glass with a weight into a solution of hydrofluoric acid. When the glass dissolves in the acid, the weight will fall to the bottom of the flask.

Chemical experiments with smoke emission

Chemical reactions with
smoke emission
(ammonium chloride)

Let's do a beautiful experiment to get thick white smoke. To do this, we need to prepare a mixture of potash (potassium carbonate K 2 CO 3) with an ammonia solution (ammonia). Mix the reagents: potash and ammonia. Add a solution of hydrochloric acid to the resulting mixture. The reaction will begin already at the moment when the flask with hydrochloric acid is brought close to the flask containing ammonia. Carefully add hydrochloric acid to the ammonia solution and observe the formation of a thick white vapor of ammonium chloride, the chemical formula of which is NH 4 Cl. The chemical reaction between ammonia and hydrochloric acid proceeds as follows:

HCl + NH 3 → NH 4 Cl

Chemical experiments: the glow of solutions

Glow reaction solution

As noted above, the glow of solutions is a sign of a chemical reaction. Let's conduct another spectacular experiment, in which our solution will glow. For the reaction, we need a solution of luminol, a solution of hydrogen peroxide H 2 O 2 and crystals of red blood salt K 3. Luminol- a complex organic substance, the formula of which is C 8 H 7 N 3 O 2. Luminol is highly soluble in some organic solvents, while it does not dissolve in water. The glow occurs when luminol reacts with some oxidizing agents in an alkaline medium.

So, let's start: add a solution of hydrogen peroxide to luminol, then add a handful of red blood salt crystals to the resulting solution. For greater effect, try conducting the experiment in a dark room! As soon as the blood red salt crystals touch the solution, a cold blue glow will immediately be noticeable, which indicates the course of the reaction. The glow in a chemical reaction is called chemiluminescence

Another chemical experience with luminous solutions:

For it, we need: hydroquinone (formerly used in photographic equipment), potassium carbonate K 2 CO 3 (also known as "potash"), pharmacy solution of formalin (formaldehyde) and hydrogen peroxide. Dissolve 1 g of hydroquinone and 5 g of potassium carbonate K 2 CO 3 in 40 ml of pharmacy formalin (formaldehyde aqueous solution). Pour this reaction mixture into a large flask or bottle with a capacity of at least one liter. In a small vessel, prepare 15 ml of concentrated hydrogen peroxide solution. You can use hydroperite tablets - a combination of hydrogen peroxide with urea (urea will not interfere with the experiment). For greater effect, go into a dark room, when your eyes get used to the dark, pour the hydrogen peroxide solution into a large vessel with hydroquinone. The mixture will begin to foam (hence the need for a large vessel) and a distinct orange glow will appear!

The chemical reactions in which the glow appears do not occur only during oxidation. Sometimes the glow occurs during crystallization. The easiest way to observe it is table salt. Dissolve table salt in water, and take enough salt so that undissolved crystals remain at the bottom of the glass. Pour the resulting saturated solution into another glass and add concentrated hydrochloric acid to this solution drop by drop. The salt will begin to crystallize, and sparks will fly through the solution. It is most beautiful if the experience is set in the dark!

Chemical experiments with chromium and its compounds

Multicolored chrome!... The color of chromium salts can easily change from purple to green and vice versa. Let's carry out the reaction: let's dissolve in water a few purple crystals of chromium chloride CrCl 3 6H 2 O. When boiling, the purple solution of this salt turns green. When the green solution is evaporated, a green powder of the same composition as the original salt is formed. And if you saturate a green solution of chromium chloride cooled to 0 ° C with hydrogen chloride (HCl), its color will turn purple again. How to explain the observed phenomenon? This is a rare example of isomerism in inorganic chemistry - the existence of substances that have the same composition, but different structure and properties. In the violet salt, the chromium atom is bound to six water molecules, and the chlorine atoms are counterions: Cl 3, and in green chromium chloride they change places: Cl 2H 2 O. In an acidic environment, dichromates are strong oxidizing agents. Their recovery products are Cr3+ ions:

K 2 Cr 2 O 7 + 4H 2 SO 4 + 3K 2 SO 3 → Cr 2 (SO 4) 3 + 4K 2 SO 4 + 4H 2 O.

Potassium chromate (yellow)
dichromate - (red)

At a low temperature, violet crystals of potassium chromium alum KCr (SO 4) 2 12H 2 O can be isolated from the resulting solution. The dark red solution obtained by adding concentrated sulfuric acid to a saturated aqueous solution of potassium dichromate is called “chromic peak”. In laboratories, it is used for washing and degreasing chemical glassware. The dishes are carefully rinsed with chromic, which is not poured into the sink, but is used repeatedly. In the end, the mixture becomes green - all the chromium in such a solution has already passed into the Cr 3+ form. A particularly strong oxidizing agent is chromium (VI) oxide CrO 3 . With it, you can light an alcohol lamp without matches: just touch the wick moistened with alcohol with a stick with several crystals of this substance. When CrO 3 is decomposed, dark brown chromium (IV) oxide powder CrO 2 can be obtained. It has ferromagnetic properties and is used in the magnetic tapes of some types of audio cassettes. The body of an adult contains only about 6 mg of chromium. Many compounds of this element (especially chromates and dichromates) are toxic, and some of them are carcinogens, i.e. capable of causing cancer.

Chemical experiments: the reducing properties of iron

Ferric chloride III

This type of chemical reaction is redox reactions. To carry out the reaction, we need diluted (5%) aqueous solutions of iron (III) chloride FeCl 3 and the same solution of potassium iodide KI. So, a solution of iron (III) chloride is poured into one flask. Then add a few drops of potassium iodide solution to it. Observe the color change of the solution. The liquid will take on a reddish-brown color. The following chemical reactions will take place in the solution:

2FeCl 3 + 2KI → 2FeCl 2 + 2KCl + I 2

KI + I 2 → K

Ferric chloride II

Another chemical experiment with iron compounds. For it, we need dilute (10–15%) aqueous solutions of iron (II) sulfate FeSO 4 and ammonium thiocyanate NH 4 NCS, bromine water Br 2. Let's start. Pour a solution of iron(II) sulfate into one flask. 3-5 drops of ammonium thiocyanate solution are also added there. We notice that there are no signs of chemical reactions. Of course, iron(II) cations do not form colored complexes with thiocyanate ions. Now add bromine water to this flask. But now the iron ions "given themselves out" and colored the solution in a blood-red color. this is how the (III) ion of valence iron reacts to thiocyanate ions. Here's what happened in the flask:

Fe(H 2 O) 6 ] 3+ + n NCS– (n–3) – + n H 2 O

Chemical experiment on the dehydration of sugar with sulfuric acid

Sugar dehydration
sulfuric acid

Concentrated sulfuric acid dehydrates the sugar. Sugar is a complex organic substance whose formula is C 12 H 22 O 11. Here's how it goes. Powdered sugar is placed in a tall glass beaker, slightly moistened with water. Then a little concentrated sulfuric acid is added to the wet sugar. mix gently and quickly with a glass rod. The stick is left in the middle of the glass with the mixture. After 1 - 2 minutes, the sugar begins to turn black, swell and rise in the form of a voluminous, loose black mass, taking the glass rod with it. The mixture in the glass gets very hot and smokes a little. In this chemical reaction, sulfuric acid not only removes water from sugar, but also partially turns it into coal.

C 12 H 22 O 11 + 2H 2 SO 4 (conc.) → 11C + CO 2 + 13H 2 O + 2SO 2

The released water during such a chemical reaction is mainly absorbed by sulfuric acid (sulfuric acid "greedily" absorbs water) with the formation of hydrates, hence the strong release of heat. And carbon dioxide CO 2, which is obtained during the oxidation of sugar, and sulfur dioxide SO 2 raise the charring mixture up.

Chemical experiment with the disappearance of an aluminum spoon

Mercury nitrate solution

Let's carry out another funny chemical reaction: for this we need an aluminum spoon and mercury nitrate (Hg (NO 3) 2). So, take a spoon, clean it with fine-grained sandpaper, then degrease it with acetone. Dip a spoon for a few seconds in a solution of mercury nitrate (Hg (NO 3) 2). (remember that mercury compounds are poisonous!). As soon as the surface of the aluminum spoon in the mercury solution becomes gray, the spoon must be removed, washed with boiled water and dried (wetting, but not wiping). After a few seconds, the metal spoon will turn into fluffy white flakes, and soon only a grayish pile of ash will be left of it. This is what happened:

Al + 3 Hg(NO 3) 2 → 3 Hg + 2 Al(NO 3) 3 .

In the solution, at the beginning of the reaction, a thin layer of aluminum amalgam (an alloy of aluminum and mercury) appears on the surface of the spoon. The amalgam then turns into fluffy white flakes of aluminum hydroxide (Al(OH) 3). The metal consumed in the reaction is replenished with new portions of aluminum dissolved in mercury. And, finally, instead of a shiny spoon, white Al (OH) 3 powder and tiny droplets of mercury remain on the paper. If, after a solution of mercury nitrate (Hg (NO 3) 2), an aluminum spoon is immediately immersed in distilled water, then gas bubbles and white flakes will appear on its surface (hydrogen and aluminum hydroxide will be released).