"Pharaoh's snakes": entertaining chemistry. How to make "pharaoh snakes" at home?

For many, chemistry lessons are a real torture. But if you have even a little understanding of this subject, you can conduct entertaining experiments and get pleasure from it. Yes, and teachers will not hurt to interest their students. For this, the so-called pharaoh snakes are perfect.

origin of name

Certainly the origin of the name "Pharaoh's snake" is not known by anybody, but it is timed to the biblical events. In order to impress Pharaoh, the prophet Moses, on the advice of the Lord, cast his staff on the ground, and he turned into a serpent. Once in the hands of the chosen one, the reptile became again a staff. Although, in fact, there is nothing in common between the way these experiments are obtained and the biblical events.

From what you can get "pharaoh snakes"

The most common substance for the production of snakes is mercuric thiocyanate. However, experiments with it can be carried out only in a well-equipped chemical laboratory. The substance is toxic and has an unpleasant persistent odor. A "Pharaoh's snake" at home can be created from tablets that are sold in any pharmacy without a prescription, or mineral fertilizers from the hardware store. To conduct the experiment, calcium gluconate, urotropine, soda, powdered sugar, saltpetre and many other substances are used, which can be purchased at a pharmacy or a store.

"Snakes" from tablets containing sulfonamides

The easiest way to spend at home is the experience of "Pharaoh's snakes" from the medicines of the sulfanilamide group. These are such drugs as Streptocide, Biseptol, Sulfadimezin, Sulfadimetoksin and others. These drugs are in the house almost everyone. "Pharaoh's snakes" made of sulfonamides turn out to be shiny gray in color, in structure they resemble corn sticks. If you gently pick up the "head" of the snake with a clamp or tweezers, then you can pull out a long reptile from one tablet.

In order to conduct the chemical experience of "Pharaoh's snake", you will need a burner or dry fuel and the above medicines. Several tablets are laid out on dry alcohol, which is ignited. During the course of the reaction, substances such as nitrogen, sulfur dioxide, hydrogen sulphide and water vapor are released. The reaction formula is as follows:

C ₁₁ H ₁₂ N ₄ O ₂ S + 7 O ₂ = 28 C + 2H ₂ S ↑ + 2SO ₂ ↑ + ₈ N ₂ ↑ + 18 H ₂ O

This experience should be carried out very carefully, since sulfur dioxide is very toxic, as well as hydrogen sulphide. Therefore, if it is not possible to ventilate a room during the experiment or to turn on the hood, it is better to do this on the street or in a specially equipped laboratory.

"Snakes" from calcium gluconate

It is best to conduct experiments from those substances that are safe, even if they are used outside of a specially equipped laboratory. "Pharaoh's snake" from calcium gluconate is obtained quite simply.

This will require 2-3 tablets of medicinal product and a cube of dry fuel. Under the influence of flame, a reaction begins, and a gray "snake" crawls out of the tablet. Such experiments with calcium gluconate are completely safe, but nevertheless it is necessary to be cautious when conducting them. The chemical reaction formula is as follows:

C ₁₂ H ₂₂ CaO ₁₄ + O ₂ = ₁₀ C + 2CO ₂ ↑ + CaO + ₁₁ H ₂ O

As you can see, there is a reaction with the release of water, carbon dioxide, carbon and calcium oxide. It is the allocation of gas that causes growth. "Pharaoh's snakes" are obtained in length up to 15 centimeters, but they are short-lived. When they try to take them in hand, they break up.

"Pharaoh's snake" - how to make of fertilizer?

If you have a garden on the plot or a dacha, then there must be different fertilizers. The most common, which can be found in the pantry of any summer resident and farmer - saltpetre or ammonium nitrate. The experiment requires sifted river sand, half a teaspoon of saltpeter, half a teaspoon of powdered sugar, a spoonful of ethyl alcohol.

It is necessary to make a depression in a slide made of sand. The larger the diameter, the thicker will be the "snake". A well-frayed mixture of saltpeter and sugar is covered in a groove and poured with ethyl alcohol. Then alcohol is ignited, a "snake" is gradually formed.

The reaction occurs as follows:

2NH ₄ NO ₃ + C ₁₂ H ₂₂ O ₁₁ = ₁₁ C + 2 N ₂ + CO ₂ + 15H ₂ O.

The allocation of toxic substances in the experience obliges to comply with safety regulations.

"Pharaoh's snake" from food

"Pharaoh's snakes" are obtained not only from medicines or fertilizers. For the experience you can use products such as sugar and soda. Such components can be found in any kitchen. From the river sand formed a hill with a deepening and impregnated with alcohol. Sugar powder and baking soda mixed in a ratio of 4: 1 and poured into the groove. Alcohol is set on fire.

The mixture begins to turn black and slowly swell. When alcohol practically ceases to burn, several wriggling "reptiles" creep out of the sand. The reaction is as follows:

2NaHCO ₃ = Na ₂ CO ₃ + H ₂ O + CO ₂ ,

C ₂ H ₅ OH + 3 O ₂ = ₂ CO ₂ + 3H ₂ O

The mixture decomposes into sodium carbonate, carbon dioxide and water vapor. It is the gases that cause the soda ash to swell and grow, which does not burn out during the reaction.

Another "reptile" from the pill

There is another simple way to get a "pharaonic snake" from medications. To do this, you will need to buy a drug "Urotropin" in the pharmacy. Instead of tablets, you can also use dry fuel containing this substance. A solution of ammonium nitrate is also needed. The drug "Urotropin" must be saturated with it. However, you can not immediately apply the entire solution to the starting material, so add a few drops and dry it. In this case, the drying should take place at room temperature.

After that, the tablet is ignited. As a result, it turns out not so much a "snake" as a "dragon". However, if you understand, this is the same experience as "Pharaoh's snakes". But because of the properties of the components there is a more violent reaction, which leads to the formation of a three-dimensional shape.

"Snake" from mercuric thiocyanate

For the first time the chemical experience of "Pharaoh's snake" was obtained from a medical student in 1820. Friedrich Wöhler mixed solutions of mercuric nitrate and ammonium thiocyanate and obtained a white crystalline precipitate. The resulting residue of mercuric thiocyanate was dried and burned by the student just for the sake of curiosity. From the burning substance began to crawl out a black and yellow serpentine mass.

"Pharaoh's snakes" from mercuric rhodanide are easy to obtain. The substance must be burned on a heat-resistant surface. The reaction will follow:

2Hg (NCS) ₂ = 2HgS + C3N4 + CS2

CS ₂ + 3 O ₂ = CO ₂ + ₂ SO ₂

Under thermal exposure, mercuric thiocyanate decomposes into mercury sulphide (black gives the reptile), carbon nitride (responsible for the yellow color of the snake), and carbon disulfide (carbon disulphide). The latter ignites and decomposes into gases - carbon dioxide and sulfur oxide, which expands carbon nitride. It, in turn, captures the mercury sulphide, and the black and yellow "Pharaoh's snakes" are obtained.

In no event can this experience be conducted at home! In addition, that toxic gases are released, mercury vapor is released. Mercury is poisonous in itself and can cause the strongest chemical poisoning.

Safety during experiments

Despite the fact that most of the substances from which "pharaoh snakes" can turn out are considered safe, experiments should be carried out very carefully. As can be seen from the above formulas, the decomposition releases sufficiently toxic components, which can lead to severe poisoning. All experiments can be carried out at home only in a ventilated room or in the presence of a high-power hood. Experiments with mercuric thiocyanate can be carried out only in a specially equipped laboratory, observing all safety rules.

In conclusion, we can say that by conducting the chemical experience "Pharaoh's snakes" in the classroom, the teacher can interest the students with his subject. Lesson, most likely, interested in even those who do not understand and do not like chemistry. And those who prefer to practice instead of boring theoretical calculations, will receive an additional stimulus to the study of science.