Freonovye snakes called a number of reactions that are accompanied by the formation of a porous product from a small volume of the reacting substances. These reactions are accompanied by the rapid evolution of gas. In the end, looks reaction as if from a mixture of reactants large snake creeps and crawls on the table like this.
On this page you will learn about reaction accompanied by the formation of "varanovich snakes, get acquainted with the equations of these reactions and will be able to see the impressive video showing the progress of such reactions. Some of these reactions can be reproduced even in the home or in the school lab - observing all safety rules, of course. And the other part reaction, fortunately, requires such reagents, which you nowhere, except in specialized laboratories will not find. Fortunately - because many of them highly toxic, and experimenting with them is not recommended.
1. Decomposition of thiocyanate (thiocyanate) mercury - Hg (CNS)2
Thermal decomposition of thiocyanate mercury goes by the equation:
2 Hg(SCN)2 = 2 HgS + CS2 + C3N4
CS2 + 3O2 = CO2 + 2SO2
When heated, the mercury thiocyanate formed black salt - mercury sulfide, carbon nitride yellow and carbon disulphide CS2. Last on the air is ignited and burns to form carbon dioxide CO2 and sulfur dioxide SO2.
The carbon nitride swells generated gases, the motion he grabs a black sulphide of mercury (II), and turns yellow-black porous mass.
In the piece of thiocyanate mercury gets out a big "snake" black and yellow, like a snake, and sometimes more than one. Blue flame, from which creeps "snake" is the burning of carbon disulfide CS2. From 1 g of ammonium thiocyanate and 2.5 g of nitrate of mercury in the right hands can turn the snake by the length of 20-30 cm
Decomposition of thiocyanate mercury - the first open-reactions of this type. Its a pioneer student of the University of Heidelberg Friedrich wöhler (1800-1882). Once in the autumn of 1820, mixing aqueous solutions of thiocyanate ammonium NH4NCS and nitrate of mercury Hg(NO3)2, it is found that from a solution of saliva. Wöhler was filtered solution and dried precipitate obtained thiocyanate mercury Hg(NCS)2. Out of curiosity, the researcher has set it on fire. The precipitate was lit up and a miracle happened: from the nondescript white ball, twisting, crawled out and began to grow long black and yellow "snake".
Mercury salts are poisonous, and working with them requires care and attention. It is safer to show snake dichromate.
2. Dichromata snake
Method 1. Mix 10 g of potassium dichromate (K2Cr2O7, 5 g of potassium nitrate KNO3 and 10 g of sugar (sucrose) C12H22O11. Then grind the mixture in a mortar and moisturize ethanol C2H5OH or collodion (it is sold in the pharmacy). Then this mixture is pressed in a glass tube with a diameter of 5-8 mm
The resulting column is pushed out from the tube and ignited at one end. Flashes barely visible light, which begins to creep in, first black, then green "snake". The mixture column with a diameter of 4 mm is illuminated with a speed of 2 mm per second. When burned, it can take 10 times!
The reaction of combustion of sucrose in the presence of two oxidizing agents potassium nitrate and potassium dichromate is quite complex. The reaction products - black particles of soot, green oxide of chromium (III) Cr2O3, the melt of potassium carbonate (K2CO3, carbon dioxide CO2 and nitrite potassium KNO2. Carbon dioxide CO2 special mixture of solid products, and makes her move.
Method 2. Mix 1 g of ammonium dichromate (NH4)2Cr2O7 2 g of ammonium nitrate, NH4NO3 and 1 g of powdered sugar. Moisten the mixture with water, the shape of her wand and air dried. If the wand to fire from it in different directions will go black and green "snake".
When ignited mixture of the following reactions occur:
(NH4)2Cr2O7 = Cr2O3 + N2 + 4H2O,
NH4NO3 = N2O + 2H2O
C12H22O11 + 6O2 = 6CO2 + 11H2O + 6C.
When the decomposition of ammonium dichromate is formed nitrogen N2, water vapor and green oxide of chromium (III) Cr2O3. The reaction proceeds with heat release. In the reaction of thermal decomposition of ammonium nitrate is allocated colorless gas, dinitrogen oxide (N2O, which is already weak when heated it decomposes to oxygen O2 and n N2. Burning sugar gives another gas - carbon dioxide CO2 , happens charring - allocation of carbon. A large amount of gas plus solid oxidation products is the secret "snake" behavior of the mixture.
3. Viper from soda and sugar
For this experience in dining plate is put 3-4 tablespoons dried sifted river sand and make him slide with a hollow in the top. Then prepare a mixture of 1 teaspoon of powdered sugar and 1/4 teaspoon of sodium bicarbonate NaHCO3 (drinking soda). Sand impregnated with 96-98%ethanol C2H5OH and poured into the recess slides prepared reaction mixture. Then set fire to the hill.
Alcohol is lit. After 3-4 minutes on the surface of the mixture appear black balls and at the base of the slope - black liquid. When almost all of the alcohol will burn, the mixture turns black, and sand slowly creeps wriggling thick black "Viper". At the base it is surrounded by a "collar" of the burning alcohol.
In this mass the following reactions occur:
2NaHCO3 = Na2CO3 + H2O + CO2,
C2H5OH + 3O2 = 2CO2 + 3H2O
Carbon dioxide CO2released during the decomposition of sodium bicarbonate and the combustion of ethyl alcohol, and water vapor vspuchivajut burning mass, forcing her to crawl like a snake. The longer burns the alcohol, the longer it turns out the "snake". It consists of sodium carbonate Na2CO3, mixed with fine particles of coal formed during combustion of sugar.
4. Nitrate worm
Instead of sodium bicarbonate can be used ammonium nitrate, NH4NO3. In the dining plate is put 3-4 tablespoons sifted river sand, turning him into a hill with a hole in the top and prepare the reaction mixture, consisting of 1/2 teaspoon of ammonium nitrate and 1/2 teaspoon of powdered sugar, thoroughly ground in a mortar. Then slides into the recess pour 1/2 tablespoon of ethyl alcohol and pour 1 teaspoon prepared with nitrate-sugar mixture. Now, if you burn the alcohol on the surface of the mixture immediately appear black balls charred sugar, and behind them rises a shiny black and thick "worm". If nitrate-sugar mixture was taken no more than 1 teaspoon, then the length of the worm will not exceed 3-4 cm And its thickness depends on the diameter of the recess slides.
The emergence of the worm caused by the interaction of ammonium nitrate with sugar, which is expressed by the following equation:
2NH4NO3 + C12H22O11 = 11C + 2N2 + CO2 + 15H2o
"Worm" in motion gases: nitrogen, N2, carbon dioxide CO2 and water vapor.
5. "Black boa" from a glass
This experience is an impressive sight. Powdered sugar in the amount of 75 g placed in a tall glass, moisten it 5-7 ml of water and stirred with a long glass rod. Then to wet sugar poured on the wand 30-40 ml of concentrated sulfuric acid H2SO4. Then the mixture is rapidly stirred with a glass rod and left in the glass.
After 1-2 minutes the contents of the glass begins to grow dark, to swell and in the form of bulky, friable and porous mass to rise, pulling up the glass wand. The mixture in the glass is strongly warmed up, even smokes a little, and slowly creeps out of the glass.
Sulfuric acid takes away from sugar (sucrose, C12H22O11) water, destroying its molecular structure, and it oxidizes, turning in sulphur dioxide SO2. In the oxidation of sugars to carbon dioxide CO2. These gases vspuchivajut formed the coal and push it out of the glass with a stick.
Equation transmitting these chemical transformations, looks like this:
C12H22O11 + 2H2SO4 = 11C + 2SO2 + CO2 + 13H2o
The carbon dioxide and sulfur together with water vapor to increase the volume of the reaction mass and force her to rise up in a narrow glass.
6. Urotropine snake
For this experience you should have patience, but it's worth it!
For an experience you will need urotropine (hexamethylenetetramine - (CH2)6N4). The methenamine tablet you can buy in the pharmacy is antiseptic drug. Come as a “hard alcohol” (dry fuel) - it can be purchased at a hardware store. Just make sure to dry the fuel that you buy contains methenamine - it can be of different types. To ensure that dry fuel contains methenamine, conduct a simple experience. Break off a few pieces of dry fuel, put them in a test tube and a little heat. If it consists of urotropine, you will feel the smell of ammonia.
To make a "snake", perform the following steps. One tablet of “hard alcohol” or drugstore urotropine put on a plate and 3-4 times impregnate a concentrated aqueous solution of ammonium nitrate, NH4NO3, dripping it from a pipette, and then drying. Every time you apply 5-10 drops (0.5 ml).
Drying of the tablets is the most tedious part of the experience: at room temperature in the air it lasts too long. But to raise the temperature to speed up the process cannot - methenamine decomposes at high temperature. Moreover, it is impossible to dry the tablets on an open fire: they can light up.
Soaked and dried tablet saucer should be set on fire with one hand. And here begins wonders: will appear black balls boiling liquid, which merge together and form a likeness of the growing tail. He bends and behind him from the fire grows thick body of the snake”. “Snake” is growing, exacerbated by the tail in the saucer begins to bend.
Decomposition of urotropine (CH2)6N4 in a mixture with ammonium nitrate, NH4NO3 leads to the formation of a porous mass consisting of carbon, and a large amount of gases - carbon dioxide CO2, nitrogen N2 and water:
(CH2)6N4 + 2NH4NO3 + O2 = 10C + 6N2 + 2CO2 + 16H2O
Interestingly, if you mix chemically pure methenamine and ammonium nitrate, dissolve without forming solid products. But in tablets at the stage of molding add binders - paraffin wax and talc. That's why you receive the “body of the snake”. And gases vspuchivajut and move it.
7. Gluconate snake
The easiest and safest way to get gluconate snakes - this is enough to bring a flame tablet gluconate calcium, which is sold in every pharmacy. You can put the tablet gluconate of calcium per tablet dry alcohol and burn it. From tablets crawl light gray snake with white spots, the amount which far exceeds the amount of the original substance - it can reach a length of 10-15 cm
The decomposition of calcium gluconate, having the composition of Sa[CH2OH(CHOH)4COO]2 · H2O leads to the formation of calcium oxide, carbon, carbon dioxide and water.
Light shade "snake" gives calcium oxide.
The disadvantage of forming a "snake" is its fragility - it crumbles quite easily.
8. Pharaoh's serpent of sulfanilamide
A very simple way of generating varanovich serpent" is the oxidative degradation of sulfa drugs (these include, for example, streptocid, sulgin sulfadimetoksin, etazol, sulfadimezin, rice, Biseptol). During the oxidation of sulfonamides has spent a lot of gaseous reaction products ( SO2, H2S , N2, water vapor), which vspuchivajut mass and form porous "snake".
The experience is carried out only under the thrust!
On the tablet dry fuel put 1 tablet drug and ignite the fuel. Thus there is a brilliant selection "Pharaoh's snake gray.
Its structure is "snake" reminds corn sticks. If eye-catching "snake" gently picked up with tweezers and gently pull, you can get a long enough "instance".
9. Decomposition of nitroacetanilide
For an experience you will need: porcelain crucible, triangle, tripod, burner, glass rod, spatula. To comply with the rules of working with concentrated sulfuric acid. When performing experience not to bend over the crucible. The experience is under traction.
Mix in a porcelain crucible organic matter white - nitroacetanilide and sulfuric acid. Heat the mixture. After a few seconds of the crucible shoot a lot of black. Gases do a lot of very porous and friable.
Black mass gives the carbon produced in large quantities. In another large quantities during the reaction gases formed SO2, NO2 and CO2, which foamed carbon.
By the way...
Why "Pharaoh's serpent"? The snake is understandable, but why Pharaoh? In the literature one can find the following explanation: "In one of the Bible says, as the prophet Moses, having exhausted all other arguments in the dispute with Pharaoh, performed a miracle by turning the rod in a sinuous snake... Pharaoh was humiliated and scared, Moses received permission to leave Egypt, and the world got a riddle". Sounds straightforward, but there is a catch: according to the Bible (book of Exodus), the prophet Moses persuaded the Pharaoh to release from slavery of the Jews, using where powerful arguments; they were called "the Ten plagues of Egypt". It was different troubles that the Lord had brought upon Egypt after another refusal of Pharaoh to let the Jewish people. None of them, incidentally, had nothing to do with snakes. Some of these terrible miracles really was accompanied by the flapping of the famous rod. And famous is that he really had to be a snake, but had done this miracle is not Moses, but the Lord himself, when he laid on his great mission, and Moses began to show cowardice.
Thus, it remains unclear why chemical snakes called "freonovye". Perhaps only because this name sounds respectable to match the efficiency of this type of reactions.