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Workout wonders. Chemical experiments

Entertaining experiments in chemistry

Entertaining experiences at home / Chemistry experiments for children

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  • Indicators - phenolphthalein
  • Indicators from natural substances
  • Indicators from juices and compotes
  • Acidity testing of foods
  • How to distinguish acids from bases
  • How to distinguish bases from acids
  • How to remove a stain from potassium permanganate
  • Starch is stained by iodine
  • Starch loses its color under the action of sodium sulfite and soda
  • Potassium permanganate stains the solution
  • Potassium permanganate purifies water
  • Detection of carbon dioxide in exhaled air
  • The formation of flakes in the reaction of potassium permanganate with sodium sulfite
  • Getting carbon dioxide from lemonade or mineral water
  • Turbidity of lime water caused by carbon dioxide
  • Turning water into blood
  • Turning tea into water
  • Lime water preparation
  • Reaction rate - experiments with soda and vinegar
Warm-up Miracles require:

Workout Miracles

If you don't get something, it doesn't matter. Skip the experience and move on to the next one. But read the description of the missed experience: someday, if the opportunity arises, you can return to it.

For the first experiment, two substances are needed that are probably found at home: baking soda (chemists call it sodium bicarbonate or bicarbonate) and vinegar. Pour a third of water into a glass, add a few drops of vinegar, and then take about a quarter of a teaspoon of soda and pour it into a glass. The mixture will immediately bubble up, as if boiling. This is how it should be: carbon dioxide is released from the solution, the same one that is in lemonade and carbonated water.

Now let's change the experience a little: do not pour soda into the vinegar solution, but dip it right in the spoon and stir it right away. Now boiling is boiling - the liquid in the glass boils and bubbles.

Let's try the third option. Prepare a clean glass plate or tile, put it on the table and put some water in the middle to make a small puddle. In two vials, prepare two solutions separately: all the same baking soda (dissolve a little powder in water) and vinegar (drop a few drops into a vial of water). From solutions of soda and vinegar, arrange two more puddles, on the sides of the first - the one from pure water. Now take a stick or a plastic straw and carefully, so as not to accidentally mix the liquid, connect the extreme puddles with the middle channel.

Of course, you already guessed what will happen next: carbon dioxide will be released. But where is he?

Have patience. One solution on the left, the other on the right, and it takes time for them to meet. And as soon as they meet, then approximately in the middle, on the border between the soda area and the vinegar area, bubbles will appear.

Having made the first chemical experiment (perhaps the first in life), it does not interfere with rest and reflection. Let's think about why soda and vinegar interact with each other either violently or lazily, slowly.

All substances are made up of molecules - you probably know this. Carbon dioxide in our experiment is released as soon as the soda molecules and vinegar molecules come into contact. When you poured soda into the vinegar solution, it also began to dissolve in water and its molecules began to collide with the vinegar molecules. They say that a reaction has begun - this word chemists call the transformations of substances, their interaction. Remember it, please, it will meet more than once, and not only in this book.

And then you began to stir the contents of the glass. And of course, helped more molecules of soda and vinegar meet, collide, connect. At the same time, carbon dioxide molecules were intensively released - and the liquid seemed to boil.

In the third experiment, with puddles on glass, we did everything the other way around: we separated the molecules, preventing them from meeting right away. However, remember how the smell of jam or perfume spreads around the apartment - it will take some time until their molecules finally reach your nose and you will feel a pleasant aroma. In the same way, numerous molecules of soda and vinegar moved slowly in the water, and when they met in the middle of the puddle, they announced this with bubbles ...

The experience is quite simple, and the explanations are long. Further it will be mostly the other way around. But here, using a simple example, you immediately learned a lot of new things: what a chemical reaction is, how it starts (remember - from the meeting of molecules), how to speed up or slow down this meeting. Just in case, I will add that very often, to speed up the reaction, to enhance it, substances are heated. As the molecules heat up, they move faster and faster, so it is even easier for them, even without our help, to find each other and react.

One last note before we move on to the next experiments. Everything that happens in flasks, glasses and vials, chemists can abbreviated to write down in the form of formulas and equations. In our case, they would write like this:


But for those who still do not know chemistry, such a record is like a rebus without a clue. Therefore, where necessary, we will describe the reaction in full, in words. In our case, this is how: when soda reacts with acetic acid, sodium acetate, water and carbon dioxide are formed. The explanation is long, but it means the same as written in the equation.

We continue the workout. We will carry out several beautiful experiments one after another and without much explanation. But first, buy a vial of tincture of iodine, a pack of phenolphthalein and a pipette at the pharmacy. Yes, perhaps, in order not to go once again, a bottle of ammonia and calcium chloride. All this costs literally a penny. Put the vials in their place, and crush the phenolphthalein tablets into powder, pour into a glass and pour two or three fingers of water into it. Stir well, let stand and pour the liquid without sediment into a clean vial. In order not to be confused, stick to the vial, as we agreed, a label with the following inscription: "Phenolphthalein solution."

Pour water from the tap into two clean glasses - no more than a third of the height. In the first glass, drop two or three drops of a solution of phenolphthalein with a pipette, in the second - pour half a teaspoon of soda ash (washing) and stir. Both liquids are completely transparent. But as soon as you pour the liquid from one glass to another, the mixture will turn crimson red. Looks like a focus. And chemists very often use this reaction. It helps them immediately recognize substances - like those found in a solution of washing soda. There are many such substances; their common name is bases.

Let's now discolor the red liquid from the previous experiment. And to make it easier than ever. Bases have adversaries they can't get along with: acids. including acetic acid. A few teaspoons of vinegar added to the raspberry solution will make it colorless again. And along the way, carbon dioxide will break free (as in experiments with baking soda).

This property - to react with bases - is inherent in all acids, not only acetic acid. You can take instead, say, citric acid, dissolving a few grains in water; the result will be the same.

Do we have any other substance that would turn phenolphthalein red? There is: ammonia. Drop a few drops into a vial or glass, dilute with water, add phenolphthalein - liquid and turn red. Pour a little acid - the color will disappear. Just do not take a lot of ammonia: it has a sharp, unpleasant smell.

Substances such as phenolphthalein are called indicators. This Latin word means "pointer"; in other words, the substance indicates whether the solution contains a base or an acid. An indicator can be, for example, a decoction of beets: in the presence of acid, it becomes brighter. Now do you understand why a little acid is sometimes added to borscht? That's right, so that it looks beautiful in plates.

And in the leaves of red cabbage there are similar substances. Boil a little of this cabbage in a saucepan with water and pour the broth into a glass. In another glass, drop a few drops of ammonia to the bottom. Now add cabbage broth to it. It will immediately turn from blue-red to greenish: this is how cabbage reacts to the base. Add some acid and see what happens.

If there is a hunt, you can check the indicator abilities of other colored decoctions. For example, from fresh or dried blueberries, blackberries, raspberries, currants. Or from brightly colored fruits - dark plums, pomegranates, cherries. And also from some flower petals: iris, violet, peony.

It is most convenient to soak narrow strips of white paper with a decoction of berries and petals and, if necessary, immerse these strips in the test solution. Chemists very often use just such pre-impregnated and dried paper (it is called indicator paper).

If, for example, a decoction of dark red peony petals itself has a purple color, then indicator paper soaked in such a decoction turns red in acid solutions, and first blue and then yellow in base solutions.

It is possible that the coloring substances of some plants will pass very poorly into hot water, and it will not be possible to prepare a bright decoction from them. Then another portion of berries or petals can be poured with a small amount of cologne or acetone; they will definitely dissolve the dyes. But remember, please: these liquids ignite easily, therefore, when working with them, be sure to make sure that no one nearby lights a match or turns on the gas.

And the indicator can also be prepared from juices diluted with water, or from compotes. To soak several dozen paper strips, half a glass of compote is enough, so it is unlikely that anyone will accuse you of extravagance. And "compote" acid-base indicators work very well. For example, an indicator from blackcurrant compote in an acid solution will be distinctly red, in a base solution it will be clearly blue...

However, we won't tell you. You yourself can already test homemade indicators and find out how they behave under different circumstances. But please, don't trust your memory: write down by all means how the color changes when your homemade indicator meets an acid or a base. I would advise you to make a tablet (it's more convenient), but you can write it down in a row on a piece of paper. Then these notes will surely come in handy, because indicators are very often needed for chemical experiments. And in this book you will meet with them more than once.

In the meantime, try to check what properties - acids or bases - in various foods. For the experiment, take milk, kefir, lemonade, mineral water, broth, etc. In order not to waste products, pour a little liquid into a vial and dip the paper strips soaked in advance with the indicator there.

Test for acidity and other substances. For example, a solution of some kind of bleaching agent or a preparation for cleaning sinks. You will see that sometimes such remedies show a reaction characteristic of acids, sometimes of bases. This is not accidental: after all, cleaning and washing ability depends on acidity. Therefore, chemists and engineers, developing each new drug, select the best ratio of acids and bases for it in advance.

Yes, here's another thing: after some training, you can show all these experiments with indicators, if you want, to your comrades as tricks. Think for yourself what spells to say so that the trick leaves a lasting impression. I hope you will guess to mention beforehand about "turning water into blood" or something like that. In the end, even these simple preparatory chemical transformations we can also consider miracles...

For the first time, I'm ready to tell you how to put the trick with "water" and "blood", although if you yourself came up with something of your own, it would be even better. Here's my advice. Paste the glass jar with colored paper and, if you want, draw some mysterious signs on it. Prepare some clean glasses. Actually, three is enough, but to make the audience think that the trick is very difficult, it is better to take five or six glasses. Add a few drops of any acid to one glass and mark it somehow so that you can immediately distinguish this glass from the rest. Pour a little washing soda into another glass, fill it with water and stir. In the third glass, of course, drop a little phenolphthalein solution. Pour plain water into a jar.

Now the focus itself. Tell the audience that the jar is pure water, and to show that this is true, take a sip or two to convince. Then fill all the glasses with water from the jar: the water will remain clear. Then pour the water from all the glasses (except, of course, in which the acid is) back into the jar. The liquid in it will turn red. Spectators will be convinced of this if they pour it into empty glasses: "water" has turned into "blood"!

Again, pour the contents of all the glasses into the jar - all of them, including the glass with acid. The liquid, as you know, will discolor. Pour it into glasses and show the audience: "blood" has become "water". Don't forget, of course, about spells. But remember: now you can not drink this "water" in any case!

Let's move on to the iodine tincture, which we recently bought at the pharmacy. For the sake of simplicity, this tincture is often called simply iodine, which is short, although inaccurate, because it contains other substances besides iodine. But iodine is important for us.

So, pour a little iodine tincture into a clean bottle and dilute with about the same amount of water. Now take out a potato, cut it with a knife and drop a drop of diluted tincture on a fresh cut from a pipette. Potatoes turn blue in front of your eyes.

But potatoes, like almost any other food, are made up of many substances. Which of them turns blue under the influence of iodine?

Blue starch. By the way, it is usually made from potatoes (although sometimes from corn or rice). At home, perhaps, there is a little starch (any). Mix a teaspoon of starch in half a glass of cold water - you get something like milk. Drop a few drops of iodine, and the "milk" will turn blue.

Of course, this is an excellent basis for another trick, you just need to drop iodine into another glass in advance and let it dry. If you then pour “milk” into it, having previously “ordered” it to turn blue, it will immediately “obey” ...

The complex substance that is formed when iodine is combined with starch is rather unstable, and the color soon disappears. This process can be further accelerated. Photo shops sell sodium sulfite; buy one bag. And if it does not appear, then the contents of a large cartridge of a conventional film developer will fit - it contains the same substance, only with additives that will not interfere with us. Dissolve some sodium sulfite in water. Cut the potato again, drop on it, as before, a diluted iodine tincture and, admiring the blue, drop a solution of sodium sulfite on the same place. The color will disappear immediately. (Do not throw away the rest of sodium sulfite - it will come in handy.)

And here's another way to get rid of the blue. A quarter of a teaspoon of starch, pour half a glass of cold water, stir and heat in a saucepan, stirring from time to time. You will get a liquid paste. Let it cool and add a few drops of iodine to turn the starch liquid blue. In the meantime, fill another glass halfway with water and add some washing soda. Now pour in there, slowly, a blue starch solution - its color will disappear before our eyes. But if you pour further, then the color will reappear and will become brighter.

The photo store sells another substance, which is called differently: sodium thiosulfate, hyposulfite. This substance also reacts with iodine, and very clearly. Pour halfway into a glass of water and add a few drops of iodine to make a solution that looks like tea in color. And now pick up a little thiosulfate with a wooden stick or a teaspoon, pour it into this "tea". And stir with a spoon. "Tea" will immediately turn into "water". Also, by the way, not bad for focus ...

Tired of the workout? Then we continue. Let's take a closer look at carbon dioxide. Moreover, so far we have dealt only with liquids and powders, and every real chemist must be able to handle gases as well.

We will get carbon dioxide at least from a bottle of mineral water (or lemonade). It is only necessary that it does not scatter in all directions, but hit where it should. It is best to do this: make a hole in a cork (cork or plastic), firmly insert a glass tube into it, put a rubber tube on it, insert another tube (at least from a pipette) into the other end of the rubber tube, and direct it where required . But you can whip up the device in a simpler way: take some dough (consult your mother or grandmother) and any flexible tube. As soon as you open the bottle, insert a tube into it and quickly cover the neck with dough. The gas has nowhere else to go, as soon as it goes into the tube ...

And we will release carbon dioxide into lime water. Ask at a construction site for quite a bit, literally a few grams, of slaked lime - they probably won't refuse you. Grind it properly and put half a teaspoon of lime in a glass. Pour hot water to the middle of the glass, stir and let stand for half an hour; a sediment will remain below, a transparent solution will appear on top, which is called lime water. Carefully, along the wall, so as not to raise a white precipitate from the bottom of the glass, pour it into another glass.

If you can't get slaked lime, here's a recipe for making it yourself: dilute a pharmacy solution of calcium chloride with water and add ammonia drop by drop until a plentiful white turbidity appears. And in this case, let the liquid settle. The clear solution that you pour into another glass will turn out to be the same lime water.

Now take a bottle of lemonade or other fizzy drink, open it and immediately insert a cork with a tube into the neck or cover the tube with dough. Dip the other end of the tube into a glass of clear lime water. Bubbles of carbon dioxide will escape from the lemonade. If they run slowly, put the bottle in warm water. These bubbles, falling into lime water, make it cloudy, whitish, like milk. In fact, a substance is formed here, which chemists call calcium carbonate. Every student knows him. And you've dealt with him more than once. Because calcium carbonate is the most common chalk. And it is clear that its small particles make water look like milk.

But do not rush to stop the experience! Donate one more bottle of lemonade to science (especially since after the experiment you can drink it, although, alas, it will be almost without bubbles). Again, quickly close the bottle with a cork or dough and continue to pass carbon dioxide through the lime water. It won't be long before the solution becomes clear again! This carbon dioxide reacted with the newly formed chalk and a new substance appeared - calcium bicarbonate. It, unlike chalk, dissolves well in water.

Carbon dioxide for such experiments can be obtained without lemonade. In general, without any devices and devices. With your own lungs.

You probably know that the air we exhale contains a lot of carbon dioxide. And if so, then it means that lime water should become cloudy from it. Let's check.

Lime water will have to be prepared again (it cannot stand for a long time - it will become cloudy on its own). When it settles, pour, as before, a clear solution into a clean glass.

Whichever way you get lime water, pour it into a small pharmacy bottle (or into a test tube if you have one), insert a glass tube or straw and blow into it several times, trying to breathe deeper. The water will become cloudy, which is a sure sign that the air you exhale contains carbon dioxide. If you want, let your friends breathe into the tube, just don't forget to change the muddy lime water to clear before each experiment.

Such an experience can also be made in color to, for example, show focus. The fact is that lime water, like washing soda, is colored red by phenolphthalein. And when the slaked lime contained in it turns into chalk, phenolphthalein no longer acts on it, and the color disappears.

Guess what the experience will look like?

Like this: add a few drops of phenolphthalein solution to fresh lime water, pour the red solution into a test tube or vial and blow through the tube. The red will turn white.

And here is a variant of this experience: a little washing soda, literally on the tip of a spoon, pour into a vial, fill (but not to the top) with water, drip 2 - 3 drops of phenolphthalein. And then blow into the pink solution. The coloring will also disappear this time, only the liquid will not be cloudy, but transparent.

The warm-up is coming to an end, a little more - and we will take with you for miracles more seriously. What would be the last chemistry exercise? Let's have this - with "potassium permanganate" from the first aid kit. If you carefully read what is written on the label, you will find out that the full chemical name of this substance is potassium permanganate. Almost black grains of permanganate, dissolving in water, give a bright purple-red solution. A very small amount of a substance, literally a pinch, can color many liters of water. Throw a few grains into a glass, fill with water and stir.

Pour half of the solution into the sink and fill the glass with water to the top (try to pour so as not to stain the sink, otherwise it will take a long time to wash it). Again, pour half a glass and a fraction of water. And so - another ten, even twenty times. The color will gradually fade, but for a very long time it will remain pink, although it seems that with such a dilution there, in the water, there is almost no "potassium permanganate" anymore.

Of course, you still have sodium sulfite from previous experiments - the one from the photoshop. A little bit of sulfite - say, a quarter of a teaspoon or even less - dissolve in a vial of water. And in the other three vials, pour, but not to the top, solutions of potassium permanganate. In the first solution, let it be dark purple. In the second vial, the solution must be diluted more strongly so that it becomes pink-red. And in the third - even stronger, to a pale pink color.

When you have completed these preparations, add to all three vials the sodium sulfite solution prepared from the beginning. Pale pink liquid will become almost colorless, pink-red - brown. And where there was a purple solution, thick brown flakes will appear. It was from "potassium permanganate" that a substance was formed, which is called manganese dioxide (or dioxide). The same substance leaves a brown coating on the sink if it is not washed off in time with running water. You rub him, you rub him - and at least he has something ...

If it is chemically soiled, then chemically it is necessary to clean it off. Try adding pharmacy hydrogen peroxide and a few drops of vinegar (or a few pinches of citric acid) to a bottle of browned solution. See what happens to the coloring.

Now you know the recipe in case you accidentally stain the sink with potassium permanganate: add a little acid to hydrogen peroxide, moisten a cloth with this solution and wipe the sink once or twice. And then rinse with clean water, and the sink will turn white again. You can get by with one citric acid, without peroxide, but then you will have to rub longer and harder.

Potassium permanganate molecules contain a lot of oxygen, the very oxygen that we all need for breathing. And in the right conditions, the molecules donate excess oxygen. Then they say that they oxidize some substance. In our recent experiment, potassium permanganate oxidized sodium sulfate. But in general, they say about him that he is a strong oxidizing agent: he can give oxygen to various substances. And at the same time change them so that they become harmless from harmful. That is why "potassium permanganate" is kept in first-aid kits: it disinfects wounds, destroys many dangerous microbes. How? Yes, oxidation!

Let's check these properties on such a simple experiment. Pour clean, fresh water into one vial, and long-standing water into the other, and even better from a swamp or an old puddle. Add a little oxidizing agent to both vials - a pink solution of potassium permanganate. In clean water, it will remain pink. And in the water from the puddle it will discolor. In stagnant water, many substances of little use accumulate, especially in warm weather. Potassium permanganate oxidizes them, destroys them, and at the same time becomes discolored.

By the way, experienced tourists take a little "potassium permanganate" with them on a hike. Even if after boiling the water is in doubt - is it possible to drink it? - then a few grains of this substance will make it quite safe. Just do not put a lot of "potassium permanganate": a pale pink solution is what you need.

Author: Olgin O.M.

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Comments on the article:

Shiro dyakuyu for cicavi doslidi.

Thank you! I, an adult, read with great interest! Be sure to read and experiment with your child!

Class!!! [up]

Thank you very much for the article, it is a great joy and important knowledge not only for children, but also for adults.

A very useful article. As an adult, it's fun for me. Will have to try the experiment. [lol]

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