For many, chemistry lessons are a real torment. But if you have at least a little understanding of this subject, then you can conduct entertaining experiments and enjoy it. Yes, and teachers will not hurt to interest their students. For this, the so-called pharaoh snakes are perfect.
Origin of the name
No one knows for sure the origin of the name "Pharaoh's snakes", but they date it to the biblical events. In order to impress the pharaoh, the prophet Moses, on the advice of the Lord, threw his staff on the ground, and it turned into a snake. Once in the hands of the chosen one, the reptile again became a staff. Although in fact there is nothing in common between how these experiments are obtained and biblical events.
From what you can get "Pharaoh snakes"
The most common substance for obtaining snakes is mercury thiocyanate. However, experiments with it can only be carried out in a well-equipped chemical laboratory. The substance is toxic andhas an unpleasant 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 a hardware store. For the experiment, calcium gluconate, urotropin, soda, powdered sugar, s altpeter and many substances that can be purchased at a pharmacy or store are used.
"Snakes" from tablets containing sulfonamides
The easiest way is to conduct the "Pharaoh's Serpent" experiment at home from drugs of the sulfanilamide group. These are such means as "Streptocide", "Biseptol", "Sulfadimezin", "Sulfadimetoksin" and others. Almost everyone has these drugs in the house. "Pharaoh's snakes" from sulfonamides are obtained in a brilliant gray color, in structure they resemble corn sticks. If you carefully pick up the "head" of the snake with a clamp or tweezers, you can pull out a fairly long reptile from one tablet.
In order to conduct a chemical experiment "Pharaoh's Serpent", you will need a burner or dry fuel and the above medicines. Several 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:
C11H12N4O2 S+7O2=28C+2H2S↑+2SO2↑+8N2↑+18H 2O
This experiment must be carried out very carefully, since sulfur dioxide is very toxic, just like 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.
"Snakes" from calcium gluconate
It is best to conduct experiments with substances that are safe, even if used outside of a specially equipped laboratory. "Pharaoh's snake" from calcium gluconate is obtained quite simply.
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 tablet. Such experiments with calcium gluconate are quite safe, but you should still be careful when conducting them. The chemical reaction formula is as follows:
C12H22CaO14+O2=10C+2CO 2↑+CaO+11H2O
As you can see, a reaction occurs with the release of water, carbon dioxide, carbon and calcium oxide. It is the release of gas that causes growth. "Pharaoh 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 snake" - how to make fertilizer?
If you have a garden on your backyardplot or cottage, then there are necessarily various fertilizers. The most common, which can be found in the pantry of any summer resident and farmer, is s altpeter or ammonium nitrate. For the experiment, you will need sifted river sand, half a teaspoon of s altpeter, half a teaspoon of powdered sugar, a spoonful of ethyl alcohol.
It is necessary to make a depression in the sand hill. The larger the diameter, the thicker the "snake" will be. A well-ground mixture of s altpeter and sugar is poured into a recess and poured with ethyl alcohol. Then the alcohol is set on fire, gradually forming a "snake".
The reaction in this case is the following:
2NH4NO3 + C12H22 O11=11C + 2N2 + CO2 + 15H 2O.
The release of toxic substances during the experiment obliges to observe safety precautions.
Food Pharaoh Serpent
"Pharaoh's 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 recess is formed from river sand and soaked with alcohol. Powdered sugar and baking soda are mixed in a ratio of 4: 1 and poured into the recess. Alcohol is set on fire.
The mixture begins to turn black and slowly swell. When the alcohol almost ceases to burn, several writhing "reptiles" crawl out of the sand. The reaction is as follows:
2NaHCO3=Na2CO3 +H2O + CO2, C2H5OH + 3O2=2CO2 + 3H2O
Mixture decomposes into sodium carbonate, carbon dioxide and water vapour. 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 easy way to get the "pharaoh's snake" from drugs. To do this, you will need to purchase the drug "Urotropin" at the pharmacy. Instead of tablets, dry fuel containing this substance can also be used. You will also need a solution of ammonium nitrate. The drug "Urotropin" must be impregnated with it. However, the entire solution cannot be immediately applied to the starting material, so it is necessary to add a few drops and dry. In this case, drying should occur at room temperature.
After that, the pill is set on fire. The result is not so much a "serpent" as a "dragon". However, if you look at it, it's the same "Pharaoh's Serpent" experience. But due to the properties of the components, a more violent reaction occurs, which leads to the formation of a three-dimensional figure.
"Snake" from mercury thiocyanate
The first chemical experiment "Pharaoh's Serpent" was obtained by a medical student in 1820. Friedrich Wöhler mixed solutions of mercury nitrate and ammonium thiocyanate and obtained a white crystalline precipitate. The student dried the resulting precipitate of mercury thiocyanate and set it on fire just for the sake of curiosity. From the burning substance began to crawl black and yellowserpentine mass.
"Pharaoh snakes" from mercury thiocyanate are obtained simply. The substance must be ignited on a heat-resistant surface. There will be a reaction:
2Hg(NCS)2=2HgS + C3N4 + CS 2
CS2 + 3O2=CO2 + 2SO 2
Under thermal action, mercury thiocyanate decomposes into mercury sulfide (gives the "reptile" a black color), carbon nitride (responsible for the yellow color of the snake) and carbon disulphide (carbon disulfide). The latter ignites and decomposes into gases - carbon dioxide and sulfur oxide, which swell carbon nitride. This, in turn, captures mercury sulfide, and black and yellow "pharaoh's snakes" are obtained.
This experiment should never be done at home! In addition to the release of toxic gases, mercury vapor is released. Mercury is poisonous in itself and can cause severe chemical poisoning.
Experimental safety
Despite the fact that most of the substances that can make "Pharaoh's snakes" are considered safe, experiments must be carried out very carefully. As can be seen from the above formulas, during decomposition, rather toxic components are released, which can lead to severe poisoning. All experiments can be carried out at home only in a ventilated room or with a high-power hood. Experiments with mercury thiocyanate can only be carried out in a specially equipped laboratory,observing all safety regulations.
In conclusion, we can say that by conducting the chemical experiment "Pharaoh's snakes" in the classroom, the teacher can interest students in his subject. Even those who do not understand and do not like chemistry will most likely be interested in the lesson. And those who prefer practice over boring theoretical calculations will have an additional incentive to study science.
