"Pharaoh's Snakes": entertaining chemistry. How to make "pharaoh snakes" at home? Research "Pharaoh's snakes" in chemistry chemistry project (grade 9) on the topic Chemical experiment of the pharaoh's snake

Pharaoh snakes are a number of reactions that are accompanied by the formation of a porous product from a small volume of reacting substances. These reactions are accompanied by rapid gas evolution. As a result, the reaction looks as if a big snake and crawls across the table like a real one.

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The most spectacular snake crawls out when mercury thiocyanate decomposes. A small piece of this substance can give birth to a monster simply gigantic size. But getting it or getting it for an experiment, unless you know chemists, of course, will be quite difficult. And the mercury vapor released during this reaction is very dangerous, so it is strictly not recommended to carry out such an experiment at home.

To carry out the experiment yourself, there is a special “homemade” pharaoh snake, all the ingredients of which are found in every home, or at least they are not at all difficult to get. Just imagine, all you need is powdered sugar, baking soda, 96% ethyl alcohol (the same one that is in first aid kits for external use) and dry river sand.

Pour 3-4 tablespoons of dry sifted river sand into a dinner plate and make a slide out of it with a depression at the top. Then prepare a mixture consisting of 1 teaspoon of powdered sugar and 1/4 teaspoon of soda. The sand is soaked in alcohol and the prepared reaction mixture is poured into the recess of the slide. Then they set the hill on fire. The alcohol catches fire. After 3–4 minutes, black balls appear on the surface of the mixture. When almost all the alcohol has burned, the mixture turns black, and a wriggling, thick black “viper” slowly crawls out of the sand. At the base it is surrounded by a collar of dying alcohol.

It’s even easier to carry out the experiment if you just buy calcium gluconate tablets at the pharmacy and set them on fire. All the substances necessary for the reaction are already contained inside them. But the effect will not be so amazing.

How to attract children to chemistry? - Show an interesting, spectacular, stunning experiment! “But such an experiment requires equipment, materials, knowledge,” you say. And... you will be wrong! For a minimal but equally spectacular pharaoh snake, all you have to do is go to a drug store and then to a Hunter/Angler or hardware store. And take some precautions, the same as, for example, when launching fireworks, that is, be careful with fire.

This is exactly the kind of experiment - the classic “Pharaoh’s Snake”, which appears as if out of nowhere, sways, sometimes hisses, sometimes sparkles and always makes an impression. Pharaoh's Snakes includes a large number of chemical colorful demonstrations with various reagents and equipment. I will try to tell you about the simplest chemicals in terms of availability and safety for humans, but not always the simplest in terms of preparation, so don’t be too lazy. Although the first "snake" will be for the lazy too :)

A small historical digression

I've come across a dozen explanations of where the name "Pharaoh's Snake" came from. The three most frequently mentioned are:

After the victory of the army of the pharaoh of the Southern Kingdom of Narmer over the army of the Northern Kingdom, it was as if a handful of priests from the North did not want to recognize Narmer as the winner, demanding divine evidence. And then the pharaoh's scepter turned into a huge smoky snake and swallowed them up.
The magician, priest and prophet Zarathushtra had two eldest sons: Urvatat-nara and Hvara-chitra. They argued among themselves who should be a warrior and who should be a farmer. Then Zarathushtra turned his staff into a fiery and smoky snake, turning its head towards Hvara-chitra, and its tail towards Urvatat-nara. The wise and cunning Zarathushtra said that the tail indicates a farmer, and the head indicates a warrior. True, there is not a word about pharaohs in the explanation :)
From the Bible: “And the Lord spoke to Moses and Aaron, saying: If Pharaoh says to you: perform a miracle, then you tell Aaron: take your rod and throw it before Pharaoh - he will become a serpent. Moses and Aaron came to Pharaoh, and did as The Lord commanded. And Aaron cast his rod before Pharaoh and before his servants, and he became a serpent. And Pharaoh called the wise men and the magicians; Aaron's rod swallowed up their rods. Pharaoh's heart was hardened, and he did not listen to them, as the Lord had spoken." "Exodus" Chapter 7. Verses 8 - 13.

Perhaps there is some truth in each explanation. I suspect that the priests and “magicians” of antiquity could well have been able to create such snakes, fooling the flock and spectators and convincing them of their power :). Be that as it may, we are not going to fool anyone; we will tell about each “snake”, why and how it turns out.

Well, now let's move on to our snakes

The simplest pharaoh snake or gluconate python

It is truly the easiest to implement. And you will need a maximum of 60 rubles worth of materials. Buy a pack of dry fuel tablets from a hardware store or a store that sells hunting and fishing equipment. Buy calcium gluconate tablets at the pharmacy, the cheapest, uncoated. You will also need matches (a lighter is also suitable, but it is more convenient to light a tablet of dry fuel with matches).

Attention! Conduct the display only in a fire-safe place! Make sure that children do not come close to a burning dry fuel tablet!

It is better to conduct the experiment in calm weather or in a windproof place. Place a tablet of dry fuel on a non-flammable surface and place a tablet of calcium gluconate on top. Set fire to dry fuel (in the video the tablet is set on fire from only one side, as a result the “snake” tilts to one side, if you want a straighter “snake”, try to set fire to the tablet at the same time as different sides), watch. A tablet of dry fuel burns from 8 to 13 minutes; as a rule, the “snake” will grow during this entire time. The maximum length of a snake that I have ever recorded is a little more than 30 centimeters.

What happens to calcium gluconate during heating? The reaction is simple:

Ca 2 + O 2 → CO 2 + Ca(OH) 2 + H 2 O + C

I deliberately did not equalize the coefficients:

it is not calcium hydroxide that is formed, but an oxide, but, as a rule, calcium oxide has time to react with the water released in the reaction

More dangerous snake or sulfa viper

Haven't you burned all the dry fuel tablets yet? Then go to the pharmacy again and buy the cheapest of the sulfonamides in the form of tablets of 0.5 grams (maybe there are more? Then you can take more) without a coating. For example, streptocide, sulfadimethoxine, sulgin, etazol, phthalazole, sulfadimezin, norsulfazole, etc. Don't take Biseptol - it's expensive. Or look in the medicine cabinet, you might even find an expired one - even better: it won’t bother your conscience.

Attention! Conduct the display only in a fire-safe place! The experiment produces toxic gases! It is best to conduct the experiment under draft or outdoors with a light wind blowing away from you. Make sure that children do not come close to a burning dry fuel tablet!

So, place a tablet of dry fuel on a non-flammable surface, and place a tablet of sulfanilamide on top. Light it, move away to the direction from which the wind is blowing, or close the draft glass and turn on the weak outflow. Depending on which sulfonamide you bought, the snake will have a different thickness. By the way, this snake can be controlled (do it only under traction!) - you can pick up its tip with tweezers and drag it slightly - it will lose weight and stretch out. During combustion of sulfonamide, toxic gases are released (sulfur dioxide, hydrogen sulfide, possible small amounts of sulfuric anhydride and nitrogen oxides) and non-toxic ( carbon dioxide, nitrogen), which swell the mass of forming carbon. Such a snake, in addition to a colorful demonstration, also has more down-to-earth qualities: instead of fumigating the room with sulfur, you can use a couple of snakes like this. Rats do not enter a room that has been “fumigated” with a sulfa viper for a very long time; they leave the holes in which this snake was set on fire. However, remember that after fumigating a room, it is better not to stay in it for a while, as you risk getting poisoned!

The snake has a metallic tint and looks a lot like a giant steel wool. Once burned it is safe.

Well, let’s write the combustion reaction of sulfanilamide using sulfadimethoxine as an example:

C 12 H 14 N 4 O 4 S+ O 2 → CO 2 + N + SO 2 + H 2 O + C + H 2 S

I didn't equalize the odds again:

in some cases, hydrogen sulfide is partially or completely oxidized to sulfur dioxide and water
nitrogen oxides and sulfuric anhydride (SO 3) may be released
how much carbon is burned to form carbon dioxide depends on the conditions

sand snake

You will need washed (clean) dried sand, preferably coarse, pure alcohol, soda and sugar. This experiment is relatively safe (on a small scale) so that it can be carried out, for example, in the kitchen, but it is still necessary to remember safety precautions when working with alcohol and fire.

Create a slide of sand on a plate with a depression at the top (in fact, the larger the slide and the wider the diameter of the depression, the thicker and longer the snake will be. But do not overdo it - firstly, it is more dangerous, and secondly, it can fall into pieces), soak it in alcohol. Pour a pre-prepared mixture of baking soda and sugar into the cavity (the ratio of soda and sugar is 1:4). You can be guided by an approximate ratio: for a glass of sand you need to take half a teaspoon of soda and 2 teaspoons of sugar. Set the "slide" on fire. The alcohol will ignite and the “slide” will begin to flame. Gradually, the mixture at the top will begin to turn black and soon a black snake-like mass will climb out of the “crater” - our snake.

Now about what happens in the experiment: sodium bicarbonate turns into carbonate with the release of carbon dioxide and water vapor:

2NaHCO 3 = Na 2 CO 3 + H 2 O + CO 2

alcohol burns in air, again producing carbon dioxide and water:

C 2 H 5 OH + 3O 2 = 2CO 2 + 3H 2 O

sugar burns with a lack of oxygen, forming carbon dioxide, water and carbon (the reaction is not equalized due to the fact that the amount of oxygen is unknown):

C 12 H 22 O 11 + O 2 → CO 2 + H 2 O + C

Actually, coal together with sodium carbonate, foamed with gases, creates the effect of a snake.

I am not going to finish the material here. There are other options for creating a pharaoh snake, which I will talk about later.

A large black snake grows out of a pile of sugar and soda

Complexity:

Danger:

Do this experiment at home

Reagents

Safety

Wear safety glasses before starting the experiment.

Conduct the experiment on a tray.

When conducting the experiment, keep a container of water nearby.

Place the burner on a cork stand. Do not touch the burner immediately after completing the experiment - wait until it cools down.

General safety rules

Do not allow chemicals to come into contact with your eyes or mouth.
Keep people away from the experiment site without protective glasses, as well as small children and animals.
Keep the experimental kit out of the reach of children under 12 years of age.
Wash or clean all equipment and fixtures after use.
Ensure that all reagent containers are tightly closed and stored properly after use.
Make sure all disposable containers are disposed of correctly.
Use only the equipment and reagents provided in the kit or recommended by current instructions.
If you have used a food container or glassware for experiments, throw it away immediately. They are no longer suitable for storing food.

First aid information

If reagents come into contact with your eyes, rinse thoroughly with water, keeping the eye open if necessary. Contact your doctor immediately.
If swallowed, rinse mouth with water and drink a little clean water. Do not induce vomiting. Contact your doctor immediately.
If reagents are inhaled, remove the victim to fresh air.
In case of skin contact or burns, wash the affected area a large number water for 10 minutes or longer.
If in doubt, consult a doctor immediately. Take the chemical reagent and its container with you.
In case of injury, always seek medical attention.

Improper use of chemicals can cause injury and damage to health. Carry out only the experiments specified in the instructions.
This set of experiences is intended for children 12 years and older only.
Children's abilities vary significantly even within age group. Therefore, parents conducting experiments with their children should use their own discretion to decide which experiments are appropriate and safe for their children.
Parents should discuss safety rules with their child or children before experimenting. Special attention Care should be taken to safely handle acids, alkalis and flammable liquids.
Before starting experiments, clear the experiment site of objects that may interfere with you. Storage should be avoided food products near the testing site. The testing area should be well ventilated and close to a tap or other water source. To conduct experiments, you will need a stable table.
Substances in disposable packaging must be used completely or disposed of after one experiment, i.e. after opening the package.

Frequently Asked Questions

Dry fuel (urotropine) does not spill out of the jar. What to do?

Hexamine may clump during storage. To still pour it out of the jar, take a black stick from the set and carefully break up the lumps.

It is not possible to form methenamine. What to do?

If methenamine is not pressed in the mold, pour it into plastic cup and add 4 drops of water. Mix the moistened powder well and put it back into the mold.

You can also add 3 drops of soap solution from the Tin set that you received with the Monster Chemistry set.

Can this snake be eaten or touched?

When working with chemicals you need to follow an unshakable rule: never taste anything from what you got as a result chemical reactions. Even if in theory it is a safe product. Life is often richer and more unpredictable than any theory. The product you get may not be the one you expected, chemical glassware may contain traces of previous reactions, and chemical reagents may not be pure enough. Experiments with tasting reagents can end sadly.

This is why eating anything is prohibited in professional laboratories. Even the food you brought with you. Safety first!

Is it possible to touch the “snake”? Be careful, it may be hot! The coal that makes up the snake can smolder. Make sure the snake is cool enough to handle. The snake gets dirty - don’t forget to wash your hands after the experiment!

Other experiments

Step by step instructions

Take a dry fuel burner from the starter kit and place foil on it. Attention! Use a cork stand to avoid damaging your work surface.

Place the plastic ring in the center of the foil.

Pour all the dry fuel (2.5 g) into the ring.

Press the mold into the ring to create a hole in the pile of dry fuel. Carefully remove the mold.

Remove the plastic ring by tapping it lightly.

Pour two level scoops of sugar (2 g) into a jar with 0.5 g of soda (NaHCO3) and close it with a lid.

Shake the jar for 10 seconds to mix the sugar and soda.

Pour the baking soda and sugar mixture into the hole in the dry fuel.

Set fire to dry fuel - very soon a black “snake” will begin to grow from this hill!

Expected result

Dry fuel will begin to burn. A mixture of sugar and soda in the fire will begin to turn into a large black “snake”. If you do everything correctly, you will grow a snake 15-35 cm long.

Disposal

Recycle solid waste experiment together with household waste.

What happened

Why is such a “snake” formed?

When heated, part of the sugar (C 12 H 22 O 11) burns, turning into water vapor and carbon dioxide. Combustion requires an influx of oxygen. Since the flow of oxygen into interior areas slides of sugar are difficult, another process occurs there: from high temperatures, sugar decomposes into coal and water vapor. This is how our “snake” turns out.

Why is soda (NaHCO 3) added to sugar?

When heated, soda decomposes, releasing carbon dioxide (CO 2):

Soda is added to the dough to make it fluffy when baking. And that is why we add soda to sugar in this experiment - so that the released carbon dioxide and water vapor make the “snake” airy and light. Therefore the snake can grow upward.

What is this “snake” made of?

Basically, the “snake” consists of coal, which was obtained by heating sugar and did not burn in the fire. It is coal that gives the “snake” its black color. It also contains Na 2 CO 3, resulting from the decomposition of soda when heated.

What chemical reactions occur during the formation of a “snake”?

Combustion (combination with oxygen) of sugar:

C 12 H 22 O 11 + O 2 = CO 2 + H 2 O

Thermal decomposition of sugar into carbon and water vapor:

C 12 H 22 O 11 → C + H 2 O

Thermal decomposition of baking soda into water vapor and carbon dioxide:

2NaHCO 3 → Na 2 CO 3 + H 2 O + CO 2

What is sugar and where does it come from?

A sugar molecule is made up of carbon (C), oxygen (O) and hydrogen (H) atoms. This is what she looks like:

Honestly, it's hard to see anything here. Download the MEL Chemistry app on your smartphone or tablet and you can look at the sugar molecule from different angles and better understand its structure. In the application, the sugar molecule is called Sucrose.

As you can see, this molecule consists of two parts, connected by an oxygen atom (O). You've probably heard the names of these two parts: glucose and fructose. They are also called simple sugars. Regular sugar is called compound sugar to emphasize that a sugar molecule is made up of several (two) simple sugars.

This is what they look like simple sugars:

fructose

Sugars are important building blocks of plants. During photosynthesis, plants produce simple sugars from water and carbon dioxide. The latter, in turn, can be combined into both short molecules (for example, sugar) and long chains. Starch and cellulose are long chains (polysugars) made up of simple sugars. Plants use them as building material and for storing nutrients.

The longer the sugar molecule, the more difficult it is for our digestive system digest it. That's why we love sweets so much, containing simple short sugars. But our bodies were not designed to rely primarily on simple sugars; they are rare in nature. Therefore, be careful with your consumption of sweets!

Why does soda (NaHCO 3) decompose when heated, but table salt (NaCl) does not?

This difficult question. First you need to understand what binding energy is.

Imagine a train carriage with a very uneven floor. This carriage has its own mountains, its own hollows, and depressions. A sort of small Switzerland in a carriage. A wooden ball rolls on the floor. If you let him go, he will roll down the slope until he reaches the bottom of one of the depressions. We say that the ball “wants” to take a position with a minimum potential energy, which is located just at the bottom of the depression. Similarly, atoms try to line up in a configuration in which the bond energy is minimal.

There are several subtle points here that I would like to draw your attention to. Firstly, remember that this explanation, which is said “on the fingers”, is not very accurate, but it will suit us for understanding the overall picture.

So where will the ball roll? At the very lowest point carriage? No matter how it is! He will roll into the nearest depression. And, most likely, it will remain there. Maybe there is another depression on the other side of the mountain, deeper. Unfortunately, our ball “doesn’t know” this. But if the car shakes strongly, then with a high probability the ball will jump out of its local depression and “find” a deeper hole. There we shake a bucket of gravel to compact it. The gravel knocked out of the local minimum will most likely find a more optimal configuration, and our ball will sooner reach a deeper depression.

As you may have already guessed, in the microworld the analogue of shaking is temperature. When we heat a substance, we make the entire system “shake,” just as we rocked a carriage with a ball. Atoms are detached and reattached in the most in different ways, and with a high probability they will be able to find a more optimal configuration than it was at the beginning. If it exists, of course.

We see such a process in very large quantities chemical reactions. The molecule is stable because it is located in a local depression. If we move it a little, it will get worse, and it will come back, similar to a ball, which, if you move it a little from the local depression to the side, will roll back. But it’s worth heating this substance harder so that our “car” is shaken properly, and the molecule finds a more successful configuration. This is why dynamite won't explode unless you hit it. This is why the paper won't catch fire until you heat it up. They are happy in their local holes and need a noticeable effort to force them to leave, even if there is a deeper hole nearby.

Now we can return to our original question: why does baking soda (NaHCO 3) decompose when heated? Because it is in a state of local minimum binding energies. In a kind of hollow. There is a deeper depression nearby. This is what we are talking about about the state when 2NaHCO 3 decomposed into 2Na 2 CO 3 + H 2 O + CO 2. But the molecule does not “know” about this and until we heat it up, it will not be able to get out of its local hole in order to look around and find a deeper hole. But when we heat the soda to 100-200 degrees, this process will go quickly. Soda decomposes.

Why doesn't table salt NaCl break down in a similar way? Because she is already in the deepest hole. If it is broken into Na and Cl or any other combination of them, the bond energy will only increase.

If you've read this far, well done! This is not the simplest text and not the most simple thoughts. I hope you were able to learn something. I want to warn you at this point! As I said at the beginning, this is a beautiful explanation, but not entirely correct. There are situations when the ball in the carriage will try to occupy the wrong place. deep hole. Likewise, our substance will not always tend to a state with minimal bond energy. But more about this some other time.

Pharaoh's snake is a collective name for chemical reactions that result in a multiple increase in the volume of reagents. During the reaction, the resulting substance increases rapidly, while wriggling like a snake. Why the Pharaoh's snake? Apparently there is a reference to the biblical story, when Moses demonstrated a miracle to Pharaoh by throwing his staff on the ground, which turned into a snake. Such chemical experiments are truly a miracle! The best pharaoh snakes, unfortunately, are obtained from substances that cannot be used at home, especially for children. These are mercury thiocyanate, potassium dichromate, ammonium nitrate, various strong acids, etc. Will we never be able to conduct a safe Pharaoh's Snake experience with our children at home? Don't despair, regular soda and sugar will come to our aid!

Pharaoh's snake made from soda and sugar

To conduct the Pharaoh's snake experiment at home, prepare the following ingredients:

sifted sand;
95% alcohol;
powdered sugar;
baking soda.

We pour a small hill of sand soaked in alcohol, and at the top of this hill we make a small depression. Then mix a teaspoon of powdered sugar and a quarter spoon of soda. Pour the resulting mixture into the “crater”.
Light the alcohol (this may take some time). Gradually, the mixture will begin to turn into black balls, and after all the alcohol has burned out, the mixture will suddenly turn black and a pharaoh’s snake will begin to crawl out of it!

What happened?
When alcohol burns, a decomposition reaction of soda and sugar occurs. Soda decomposes into carbon dioxide and water vapor. Gases swell the mass, so our “snake” crawls and wriggles. The snake's body consists of sugar combustion products.

Calcium Gluconate Pharaoh's Snake

It’s even easier to get Pharaoh’s snake from a calcium gluconate tablet; it is freely sold in pharmacies and you are probably already familiar with it. The tablet just needs to be set on fire and when it burns, a pharaoh's snake is formed. Unfortunately, such a pharaonic snake is very fragile, but it is quite suitable for a first acquaintance and for getting an idea.

Pharaoh's snake made of potassium permanganate

Introducing a classic chemical experiment with multiple increases in volume. Attention! Wear gloves! Add a teaspoon of potassium permanganate to a glass of water. Add a little there too liquid soap. Pour the contents of the glass into a tall and fairly narrow glass vessel. A simple cylindrical flower vase is perfect for these purposes. Now add about a third of a glass of 30% hydrogen peroxide to the vase. There is a sharp ejection of a column of foam from the vessel! And this happens almost instantly! Therefore, the experiment should be carried out in a place where you can easily minimize the consequences of contamination with this foam, for example, in a sink.

Preview:

MBOU "Sukhobezvodnaya Secondary School"

Area of expertise: chemistry

Topic:

"Pharaoh's snakes" in chemistry

Scientific supervisor:Chelnokova O.V., chemistry teacher

MBOU "Sukhobezvodnaya Secondary School"

Nizhny Novgorod region

g.o. Semyonovsky

P. Sukhobezvodnoe

2017

I.Introduction………………………………………………………………………………….3

II. Theoretical part………………………………………………………... 4

1.Pharaoh's snakes in history. ……………………………4

1.1 Pharaoh’s snakes in the history of Egypt……………….…4

1.2 Importance of snakes for Ancient Egypt.…………………………..4

2. Pharaoh snakes in chemistry……………………………………4

2.1 First steps in obtaining a pharaoh snake…………………..4

2.2 Experience of F. Wöhler…………………………………………..……..5

2.3 Types of “pharaoh snakes”……………………….……………..5

III. Practical part……………...……………………………………………………….........7

3.1. Methodology………………………………………….7

3.2. Carrying out a chemical experiment……………………….7

3.3. Addiction appearance"Pharaoh's snake" from the conditions

Carrying out a chemical experiment …………………………8

3.4. Results of the experimental part…………………..………9

IV.Conclusion……………………………………………………………………………….9

V. Literature………………………………………………………..…………....10

VI.Appendix………………………………………………………………………………........11

VII. Review………………………………………………………………………………15

I. Introduction.

"You are familiar with the old parable

About the insidious snake..."

(G. Heine, "Book of Songs")

One of the biblical legends says how the prophet Moses, having exhausted all other arguments in a dispute with Pharaoh, performed a miracle, turning the rod into a writhing snake... Pharaoh was embarrassed and frightened. A moment - and the rod was again in the hands of Moses in his in the usual form. Moses received permission to leave Egypt, and the world received another riddle.

The snake (or serpents) is an extremely common symbol in the culture of Ancient Egypt.

“...Of the many animals depicted in the art of Ancient Egypt, the snake was the most sacred and revered. Usually two snakes were depicted, topped with two royal crowns- Upper and Lower Egypt, respectively. Pharaohs were often depicted with a snake on their forehead. And the most sacred symbol was the image of two snakes on a winged disk..."

Many years passed, a lot of water passed under the bridge, until, at the end, chemists of the 19th century managed to come up with something similar to the miracle created by Moses - Wöhler’s “Thiocyanate Snake”.

Problem :

How did you manage to get the “Pharaoh’s snake”?

What is needed for this?

What signs accompany this “miracle”?

How many types of “pharaoh snakes” can you get and what conditions are necessary for this?

And most importantly, is it possible to do this in a school chemistry laboratory?

Object of study: conditions for the appearance of “pharaoh snakes”

Item : “Pharaoh snakes” in a chemical laboratory

Hypothesis : If you change the proportions in the composition of the “pharaoh snake” and the conditions of the chemical experiment, then the “pharaoh snake” will turn out with new physical properties

Purpose Our research is the study of material about pharaoh snakes, their composition, methods of production and conditions for their appearance during a chemical experiment

Tasks:

study the history of the origin of the concept of “pharaoh’s snakes”
study the composition of “pharaoh snakes”
get the "Pharaoh's snake" in the school chemistry laboratory and at home

4. identify the dependence of the appearance and composition of the “pharaoh snake” on the proportions of components and production conditions

Means: 1. Study of theoretical material.

2. Conducting a chemical experiment

3. Analysis.

The result research will be:

Material about the connection between the historical concept of “Pharaoh’s snakes” and the history of chemical experiment.
Identification of the conditions for the appearance of the “pharaoh snake” and its appearance

II. Theoretical part

1. Pharaoh's snakes in history

1.1. Pharaoh's snakes in Egyptian history

“The snake was associated with spiritual rebirth and resurrection. In the ancient Egyptian text she herself reminds of this: “I am the snake Sata, I die and am born again.” (A. Alford)

In the hieroglyph system, the image of a snail or horned snake is phonetically equivalent to the letter F, and the sign conveying the movements of the snake is Z. Both of them “refer to the primordial and cosmic forces.” The snake, like other reptiles, is also used when referring to the original - the most primitive - levels of life: it is the reptiles that are the first to greet the god Ra when he appears above the surface of the primeval waters of Nunz. (M. Kasperavičius)

According to the “Book of the Dead”: the snake is a symbol of the Earth, the snake shedding its skin serves as a symbol of the continuation of life after death

(Chapter LXXXVII).

In the Pyramid Texts, the hieroglyphic sign for "snake" is equipped with many knives in order to neutralize the dangerous animal.

Many Egyptian deities have a serpentine appearance:

Amon as a prabhód appears in the form of the serpent Kematef;

Mekhent - " Surrounding the Earth", which performs the function of the world serpent holding the earth on itself;

Kerastis - horned viper;

The following are depicted with the head of a snake: the earth god Geb - sometimes;

Female deities with the head of a snake;

Snake as an attribute: Osiris - according to the Egyptian Book, his dwelling rested on the water, and the walls were made of living snakes.

1.2 Significance of snakes to Ancient Egypt

Ancient Egypt was characterized by the use of the image of a serpent as a social classification sign of the sacred king (cobra as a symbol of the highest divine and royal wisdom and power, knowledge, gold). The cobra (goddess Uto) together with the vulture (Nekhbet), depicted on the double crown of the pharaoh, symbolize the power of the pharaoh over the united country and the divine protection of the pharaoh.

Kushite and Meroitic kings and queens are usually represented wearing cobra crowns, similar to the crowns of the pharaohs. Locally produced pottery is characterized by the symbol of a winged snake.

In Hellenistic Egypt: two snakes next to the solar disk represent the goddesses Nous and Logos, who expelled the enemies of the god Ra; a snake with a lion's head - protection from evil. (See Appendix No. 1)

2. Pharaoh's snakes in chemistry

2.1 First steps in obtaining a pharaoh snake

With sulfur, synerod forms a remarkable substance known as rhodanoic acid (thiocyanic acid, HCNS). One of its compounds with mercury, which became very famous in the 19th century due to its special properties. This is mercury thiocyanide (mercuric thiocyanide), which was used to prepare small, highly flammable cones that were known as pharaoh snakes.

The composition for preparing snakes was prepared as follows: sodium thiocyanate was poured into a weak solution of mercuric nitrate, and mercury thiocyanate precipitated out in the form of a copious precipitate, which was a white, highly flammable powder. It was collected on a filter and made into a hard dough by grinding with a solution of gum in water. Then adding a small amount of sodium nitrate to this dough, cones or cylinders about 2.5 cm high were made from it, and they were carefully dried over a water bath. When such a snake egg is completely dry, a baby hatches from it: as soon as you touch it with an ordinary lit match, the thiosine-containing compound swells little by little, the cylinder grows before your eyes and turns into a yellowish mass that expands and stretches from 45 to 60 cm in length . You might think that a real snake is wriggling in front of you in its coils, having just emerged from its cramped prison, where it was squeezed on all sides.

The residue formed after this chemical process, including, among other things, mercury syneride and paracyanium (cyanium polymer, (CN)2), is poisonous, and therefore it was thrown away or burned. It has a loose structure and disintegrates into powder at the slightest touch.

During the decomposition process of thiosine mercury, sulfur dioxide is released in large quantities, accompanying the birth of pharaoh snakes with an unpleasant, suffocating odor.

It is obvious that in our time such fun cannot be popular due to the fact that very toxic substances are used and formed in their production and during use.

2.2 F. Wöhler’s experiment

Centuries and millennia passed, alchemy gradually turned into the science of chemistry... Finally, chemists of the 19th century managed to come up with something similar to the miracle of the “Pharaoh’s snake” - Wöhler’s thiocyanate snake

One day in the fall of 1820, a very young medical student at the University of Heidelberg, Friedrich Wöhler, mixing aqueous solutions of ammonium thiocyanate NH4NCS and mercuric nitrate Hg(NO3)2, discovered that a white precipitate precipitated from the solution. Wöhler filtered the solution and dried the precipitate of the resulting mercury thiocyanate Hg(NCS)2, and then, out of curiosity, set it on fire. The sediment caught fire and a miracle happened: from a nondescript white lump, a long black and yellow “snake” crawled out and grew. After ignition, mercury thiocyanate quickly decomposes to form black mercury sulfide HgS, yellow bulky carbon nitride of composition C3N4, carbon dioxide and sulfur dioxide. The rapidly released gases cause the snake, consisting of solid reaction products, to “crawl.” It is simply amazing that from 1 g of ammonium thiocyanate and 2.5 g of mercury nitrate, in skillful hands a snake 20-30 cm long is obtained. However, mercury salts are poisonous, and working with them requires caution and attention. (See Appendix No. 2).

2.3 Types of "pharaoh snakes"

Black (pharaoh) snakes, sometimes called glow worms, are small tablets or sticks that, when ignited, burn, forming long black snakes from the combustion products. The most dangerous thing when burning these tablets is that, in some cases, toxic smoke is generated, but, on the other hand, there is no fire or explosion.

1 .Sulfanilamide snake

A very simple way to obtain “pharaoh snakes” is the oxidative decomposition of sulfonamide drugs (for example, streptocide, sulgin, sulfadimethoxine, etazol, sulfadimezin, phthalazole, biseptol). During the oxidation of sulfonamide drugs, many gaseous reaction products (SO2, H2S, N2, water vapor) are released, which swell the mass and form a porous “snake”. The experiment is carried out under traction! Place 1 tablet on a tablet of dry fuel medicinal product and set the fuel on fire. At the same time, a shiny “pharaoh snake” is released gray, which can be called “graphite snake” because of its appearance.

2. Gluconate snake

To get a gluconate snake, just bring a calcium gluconate tablet, which is sold in every pharmacy, to the flame. A snake will crawl out of the tablet, the volume of which is much greater than the volume of the original substance. Decomposition of calcium gluconate, which has the composition Ca2. H2O produces calcium oxide, carbon, carbon dioxide and water.

"Calcium gluconate" tablets can produce a light gray "snake" with white spots, approximately 10–15 cm long, which curls into a spiral when received.

The light shade of the “snake” is explained by the formation of calcium oxide during the reaction. The disadvantage of the resulting “snake” is its fragility. It crumbles quite easily.

3.Dichromate snake

Mix and then grind in a mortar 10 g of potassium dichromate K2Cr2O7, 5 g of potassium nitrate KNO3 and 10 g of sugar. The resulting powder is moistened with ethyl alcohol and collodion and pressed into a glass tube with a diameter of 4-5 mm. The result is a “stick” of the mixture, which, when ignited, forms first a black and then a green snake, which crawls out and wriggles in the same way as a thiocyanate snake: it burns at a speed of 2 mm per second and lengthens 10 times! The combustion reaction of sucrose in the presence of two oxidizing agents - potassium nitrate and potassium dichromate - is quite complex; the end result is black soot particles, green chromium oxide, molten potassium carbonate, as well as carbon dioxide and nitrogen. Gases swell a mixture of solids and cause it to move.

4 . Nitrate worm

Pour 3 - 4 tablespoons of sifted river sand into a dinner plate, make a slide out of it with a depression at the top and prepare a reaction mixture consisting of 1/2 teaspoon of ammonium nitrate and 1/2 teaspoon granulated sugar, thoroughly ground in a mortar. Then another 1/2 tablespoon of ethyl alcohol is poured into the depression of the slide and 1 teaspoon of the prepared nitrate-sugar mixture is poured. After this, all that remains is to set the alcohol on fire. Immediately, black balls of charred granulated sugar appear on the surface of the mixture, and after them a black shiny and thick “worm” grows, descending from the slide. If no more than 1 teaspoon was taken of the nitrate-sugar mixture, then the length of the worm will not exceed 3 - 4 cm. And its thickness depends on the diameter of the recess of the slide.

5. Sparkling Snake

Mercury thiocyanate is mixed with a small amount(a few drops) of starch paste, a stick is formed from the resulting mass and, after drying, is set on fire. The resulting snake will burn with a beautiful, blue, sparkling flame. During combustion, mercury sulfide will be formed, unlike thiocyanate, this is a non-toxic substance (mercury sulfide is insoluble), but still, it is better to conduct such an experiment outside the home.

6 . Soda - sugar snake.

Mix powdered sugar and baking soda in a ratio of 4:1. From the resulting mixture, something like a tubercle (mound) is formed and a small depression is made in the center. A few drops of alcohol or some other organic flammable reagent are dripped into this recess. Use a match or lighter to light the top of this bump. At first there will be a barely noticeable combustion with scattering of black balls, after the reaction is established, continuous growth will occur black snake.

7. Green pharaoh snake.

We need ammonium nitrate: powdered sugar: ammonium dichromate (2:1:1). Mix the ingredients, add a little water and form a stick, let it dry (you can use a hairdryer to speed up the process). Once dry, light one end and watch how a green snake grows instead of a black snake. Green associated with the formation of chromium(III) oxide. Chromium (III) oxide is a carcinogen, so conduct the experiment outdoors. (See Appendix No. 3).

III. Practical part

3.1. Methodology.

Having studied the theoretical material on obtaining various types“Pharaoh snakes”, we have established that they contain substances that are inaccessible and have a harmful effect on the body. The “dichromate snake” contains chromium compounds that have a toxic effect; “nitrate worm” contains ammonium nitrate, when it enters the body, acute oxygen starvation occurs; “spark snake” contains mercury compounds, which are dangerous and prohibited in a school laboratory; Green Pharaoh's Snake contains chromium (III) oxide, which is a carcinogen. Therefore, to conduct a chemical experiment, we chose those types of “pharaoh snakes”, the composition of which is accessible and does not have a harmful effect on the body.

A) Making a device and a “tablet”.

To do this, take two medical syringes (10 ml each) and cut off the lower part of one of them, where the needle is attached. The syringe is filled with the mixture. The plunger is removed from another syringe and the mixture is pressed. Then squeeze the tablet out of the syringe. The resulting tablet is placed on dry fuel and set on fire.

B) Substances: calcium gluconate (C 6 H 11 O 7 ) 2 Ca ; validol with sugar (C 12 N 22 O 11 ) sulfadimitaxine; copper oxide II (CuO); baking soda; ethyl alcohol; sugar.

B) Equipment: tripod, mesh, mortar, dry fuel, glass rod, pestle. (See Appendix No. 4).

3.2. Conducting a chemical experiment

Experience No. 1. Calcium gluconate (C 6 H 11 O 7 ) 2 Ca + sulfadimitaxin = Gray, shiny “snake” with a white head, expected result. As a result of the experiment, the result was a “snake” that was darker, very fragile and disintegrated when touched.

) + Calcium gluconate (C 6 H 11 O 7) 2 Ca = Gray-black with a “head” and spots white, expected result. As a result of the experiment, the white “head” and dark body of the “snake” are clearly defined.

Experience No. 3 Calcium gluconate (C 6 H 11 O 7 ) 2 Ca + Copper Oxide II (CuO) = Gray, with red, yellow and green spots, expected result. As a result of the experiment, the “snake” has a well-defined white “head” and red, yellow and green spots, fragile.

(See Appendix No. 5)

Experiment No. 4 Gluconate snake

Decomposition of calcium gluconate, which has the composition Ca2, upon ignition. Expected result: light gray snake with white spots. As a result of the experiment, the snake is light gray with a white head, twists into a spiral, and is fragile.

Experiment No. 5 Sugar and soda snake

Powdered sugar and baking soda in a ratio of 4: 1, in the form of a slide, a few drops of medical alcohol in the center, the mixture is set on fire. Expected result: black balls and a black snake. The experience resulted in a multitude of small, black, twisted snakes. (See Appendix No. 6)

3.3. Dependence of the appearance of the “pharaoh snake” on the conditions of the chemical experiment

Experience (proportions of substances)	Appearance of the “pharaoh snake” according to the description of the experience	Appearance of the resulting “pharaoh snake”	Conditions that must be changed to achieve the desired result
Experience No. 1. Calcium gluconate (C 6 H 11 O 7 ) 2 Ca + sulfadimitaxine (1:1)	Grey, shiny with white head "snake", expected result	Dark, loose mass, fragile, crumbles	The initial mass is not sufficiently moistened; time is required
Experience No. 2. Validol s (C 12 H 22 O 11 ) + Calcium gluconate (C 6 H 11 O 7 ) 2 Ca (1:1)	Gray-black with a “head” and white spots, the expected result	The white “head” is clearly defined, the body is twisted, several snakes appear simultaneously	Constant combustion must be maintained
Experience No. 3 Calcium gluconate (C 6 H 11 O 7 ) 2 Ca + Copper oxide II (CuO) (1:1)	Gray, with red, yellow and green spots	well-defined white “head”, red, yellow and green spots on the body, fragile	You can increase the content of copper oxide II and sufficiently moisten the mass
Experiment No. 4 Gluconate snake (1 tablet)	light gray snake with white spots	the snake is light gray with a white head, twists into a spiral, fragile	Needs constant heating
Experiment No. 5 Sugar-soda snake (1:1)	black balls and black snake	many small, black, twisted snakes, hard	It is necessary to moisten the entire mixture with ethyl alcohol

3.4. Results of the experimental part.

As a result of a chemical experiment, I received “pharaoh’s snakes” in the school chemistry laboratory and at home. Revealeddependence of the appearance and composition of the “pharaoh snake” on the proportions of the components and production conditions

During the chemical experiment, I made the following conclusions: appearance

“Pharaoh snakes” depends on the composition of the mixture, compliance with the proportions and conditions of the chemical experiment. The mixture tablet should not be too dry, as the “snake” becomes even more fragile. For wetting, add water drop by drop, stirring the mixture; if there is excess water, the tablet must be dried. Maintain a constant burn for best results.

IV. Conclusion

As a result of the research, I studied materials about the origin of the concept

"Pharaoh's snakes" in history and chemistry, their meaning and place in Egyptian culture. The history of the chemical experiment to obtain “pharaoh snakes” was studied, the possibility of obtaining different types"snake". Manufacturing the device and conducting a chemical experiment to obtain five types

"Pharaoh's snakes" in a school chemistry laboratory.

The dependence of the appearance of the “snake” on the composition and proportions of the components of the mixture and the conditions of the chemical experiment was studied. The choice of “pharaoh snake” depended on the availability of components and their safe effect on the body. Thus, the hypothesis about the influence of conditions on physical properties"Pharaoh's snake" was confirmed.

V.Literature

Entertaining tasks and effective experiments in chemistry / B.D. Stepin, L.Yu. Alikberova, 2nd ed. stereotype. - M.: Bustard, 2006. 430 p. ill.
Chemistry at school: magazine // No. 2 2007.
www.wikipedia.ru

VI.Appendix No. 1.

Egyptian pharaohEgyptian queen

Snakes in Egyptian culture

Appendix No. 2.

Friedrich Wöhler

"Pharaoh's Snake"

Appendix No. 3.

Types of "pharaoh snakes"

Appendix No. 4.

Preparatory stage.

Appendix No. 5.

Experience No. 3.

Experience No. 2.

Experience No. 1

Appendix No. 6

Experiment No. 5 (Mixture) Experiment No. 4 Experiment No. 5 (Mixture after combustion)

VII.Review

The project work is dedicated to interesting topic- Pharaoh's snakes, as a historical concept in chemistry. The author of the work sets himself the task: to study theoretical material, to find the first steps in the history of a chemical experiment to obtain pharaoh snakes, to obtain pharaoh snakes in a chemical laboratory, to analyze the dependence of the appearance of the “snake” on the composition, proportion, and conditions of the experiment. To solve the problem, the student sets goals: to find out what pharaoh snakes are, how they were obtained, to evaluate the real and safe possibility of obtaining them in a chemical laboratory. After analyzing the extensive material and capabilities of the school laboratory, a chemical experiment was conducted to obtain five types of “pharaoh snakes.” The student came to the conclusion that this experiment was possible, which confirmed her hypothesis.

Thus, project work"Pharaoh's snakes" in chemistry allowed the student to study independently research work and has cognitive interest not only among project participants, but also for students, increasing interest in the study of chemistry, subject teachers, and can be used in the classroom as information and practical material.