For many, chemistry lessons are a real torment. But if you even have a little understanding of this subject, then you can conduct entertaining experiments and enjoy it. Yes, and teachers do not hurt to interest their students. The so-called pharaoh snakes are perfect for this.
origin of name
No one knows the origin of the name “pharaoh serpents”, but they confine it to biblical events. In order to impress Pharaoh, the prophet Moses, on the advice of the Lord, threw his staff on the ground, and he turned into a snake. Caught in the hands of the chosen one, the reptile became a staff again. Although in reality there is nothing in common between how these experiments are obtained and biblical events.
What can you get "pharaonic snakes"
The most common substance for snakes is mercury thiocyanate. However, experiments with it can only be carried out in a well-equipped chemical laboratory. The substance is toxic and has an unpleasant persistent odor. A "pharaoh snake" at home can be created from tablets that are sold in any pharmacy without a prescription, or mineral fertilizers from a hardware store. For the experiment, calcium gluconate, urotropin, soda, powdered sugar, nitrate and many substances that can be purchased at a pharmacy or store are used.
"Snakes" from sulfanilamide tablets
The easiest way to conduct a home experiment "Pharaoh's snakes" from drugs sulfanilamide group. These are such drugs as Streptocid, Biseptol, Sulfadimezin, Sulfadimethoxin and others. Almost everyone has these drugs in the house. "Pharaoh snakes" from sulfanilamides are obtained in a brilliant gray color, in structure they resemble corn sticks. If you gently grab the snake's head with a clamp or tweezers, you can draw a fairly long reptile from one tablet.
In order to conduct the chemical experiment of the Pharaoh’s snake, you will need a burner or dry fuel and the above medicines. A few tablets are laid out on dry alcohol, which is set on fire. During the reaction, substances such as nitrogen, sulfur dioxide, hydrogen sulfide and water vapor are released. The reaction formula is as follows:
C 11 H 12 N 4 O 2 S + 7O 2 = 28C + 2H 2 S ↑ + 2SO 2 ↑ + 8N 2 ↑ + 18H 2 O
Such an experiment must be carried out very carefully, since sulphurous gas is very toxic, as well as hydrogen sulfide. Therefore, if it is not possible to ventilate the room during the experiment or turn on the hood, it is better to do this on the street or in a specially equipped laboratory.
Calcium Gluconate Snakes
It is best to experiment with substances that are safe, even if they are used outside a specially equipped laboratory. "Pharaoh snake" from calcium gluconate is quite simple.
This will require 2-3 tablets of the drug and a cube of dry fuel. Under the influence of the flame, a reaction begins, and a gray “snake” crawls out of the pill. Such experiments with calcium gluconate are quite safe, but you should still be careful when conducting them. The formula of the chemical reaction is as follows:
C 12 H 22 CaO 14 + O2 = 10C + 2CO 2 ↑ + CaO + 11H 2 O
As you can see, a reaction occurs with the release of water, carbon dioxide, carbon and calcium oxide. It is gas evolution that causes growth. "Pharaonic snakes" are obtained in length up to 15 centimeters, but they are short-lived. When you try to pick them up they fall apart.
"Pharaoh's snake" - how to make from fertilizer?
If you have a garden on a personal plot or a summer residence, then there are certainly various fertilizers. The most common that can be found in the pantry of any summer resident and farmer is nitrate or ammonium nitrate. For the experiment you will need sifted river sand, half a teaspoon of saltpeter, half a teaspoon of powdered sugar, a spoon of ethyl alcohol.
It is necessary to make a depression in the slide of sand. The larger the diameter, the thicker the "snake" will be. A well-ground mixture of saltpeter and sugar is poured into the recess and poured with ethanol. Then they set fire to alcohol, a "snake" is gradually formed.
The reaction in this case is as follows:
2NH 4 NO 3 + C 12 H 22 O 11 = 11C + 2N 2 + CO 2 + 15H 2 O.
The release of toxic substances during the experiment requires compliance with safety precautions.
Food Pharaoh Snake
"Pharaoh snakes" are obtained not only from medicines or fertilizers. For experience, you can use products such as sugar and soda. Such components can be found in any kitchen. A hill with a depression is formed from river sand and impregnated with alcohol. Powdered sugar and baking soda are mixed in a ratio of 4: 1 and poured into a recess. Alcohol set on fire.
The mixture begins to blacken and slowly swell. When the 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 + 3O 2 = 2CO 2 + 3H 2 O
The mixture decomposes into sodium carbonate, carbon dioxide and water vapor. It is gases that cause soda ash to bloat and grow, which does not burn during the reaction.
Another "reptile" from the pill
There is another simple way to get a “pharaoh snake" from drugs. To do this, you need to purchase the drug "Urotropin" in a pharmacy. Instead of tablets, you can also use dry fuel containing this substance. Still need a solution of ammonium nitrate. The drug "Urotropin" must be impregnated with them. However, you cannot immediately apply the entire solution to the starting material, so you need to add a few drops and dry. In this case, drying should occur at room temperature.
After that, the pill is set on fire. As a result, it turns out not so much a "snake" as a "dragon". However, if you look, it’s the same experience of the “Pharaoh Serpents”. But due to the properties of the components, a more violent reaction occurs, which leads to the formation of a three-dimensional figure.
Mercury Rodanide Snake
For the first time, the chemical experiment of the Pharaoh’s Serpent was obtained by a medical student in 1820. Friedrich Weller mixed solutions of mercury nitrate and ammonium thiocyanate and obtained a white crystalline precipitate. The student dried the resulting precipitate of mercury rhodanide and set it on fire just for the sake of curiosity. A black-yellow serpentine mass began to creep out of the burning substance.
"Pharaoh snakes" from mercury thiocyanate are obtained simply. The substance must be ignited on a heat-resistant surface. A reaction will follow:
2Hg (NCS) 2 = 2HgS + C 3 N 4 + CS 2
CS 2 + 3O 2 = CO 2 + 2SO 2
Under thermal influence, mercury rhodanide decomposes into mercury sulfide (gives the reptile black), carbon nitride (responsible for the yellow color of the snake) and carbon disulfide (carbon disulfide). The latter ignites and decomposes into gases - carbon dioxide and sulfur oxide, which swell carbon nitride. He, in turn, captures mercury sulfide, and black-yellow "pharaoh snakes" are obtained.
This experience should never be carried out at home! In addition to the emission of toxic gases, the release of mercury vapor occurs. Mercury is toxic in itself and can cause severe chemical poisoning.
Safety during experiments
Despite the fact that most of the substances from which "pharaoh snakes" can be obtained are considered safe, experiments must be carried out very carefully. As can be seen from the above formulas, decomposition produces quite toxic components that 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 mercury thiocyanate can only be carried out in a specially equipped laboratory, observing all safety rules.
In conclusion, we can say that by conducting the chemical experience of the Pharaoh Snakes in the classroom, the teacher can interest students in their subject. The lesson is likely to interest even those who do not understand and do not like chemistry. And those who prefer practice instead of boring theoretical calculations will receive an additional incentive to study science.