Red and black underwater photography

The magic charm of chemistry is not just an expression, it is amazing. The following 37 moving pictures will help you understand these chemical phenomena while leading you to appreciate the beauty of chemistry.

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1. decomposition of mercury thiocyanate ("Pharaoh's snake")

Principle: Mercury thiocyanate is decomposed by heat, and some products burn.

? 2Hg(SCN)2→ 2HgS + CS2？ + C3N4

? CS2？ + 3O2？ → CO2？ + 2SO2

? 2C3N4？ → 3(CN)2？ + N2

Trivia: Mercury thiocyanate was synthesized by Germans in 182 1 year, and the special phenomenon of its combustion was discovered soon. For a long time, it was sold as a kind of fireworks in Germany, but it was finally banned because of many accidents in which children were poisoned by eating by mistake.

Danger: high. Mercury compounds are toxic, as are mercury sulfide, sulfur dioxide and cyanide gas produced by the reaction. Don't try it yourself without a fume hood and professional guidance!

2. Matches burn

Principle: Matchhead contains red phosphorus, sulfur and potassium chlorate. The heat generated when striking matches makes red phosphorus and sulfur burn, and potassium chlorate is decomposed into oxygen to assist combustion.

Trivia: The earliest friction matches only contained sulfur. 1826, the British chemist John e walker used potassium chlorate for the first time, but his matches were very dangerous, and fireballs often fell and hit thin clothes and carpets.

Danger: Very low, but please don't give matches to children, which may cause fire.

3. Hydrogen meets fire

Principle: Hydrogen is flammable and easy to diffuse, and it can explode and burn in the air.

Trivia: What happened to the Hindenburg airship is an enlarged version of this scene.

Recorder: PRFSLO &; Dr. mo

Danger: medium. Because the explosion may hurt people, please ignite it remotely as shown in the picture.

4. Mercury and aluminum rust

Principle: Aluminum is a highly active metal, but the alumina layer on its surface makes it unable to completely react with oxygen in the air. Mercury will destroy this protective layer and make aluminum "rust" quickly.

This is time-lapse photography. The real length of this process is about half an hour. If the picture moves down, you will see a lot of aluminum rust powder below.

Trivia: This is one of the reasons why it is forbidden to carry mercury on the plane. Legend has it that during World War II, some American commandos carried mercury to destroy German planes.

Danger: moderate to low. Mercury is poisonous and inedible. Please experiment in a well-ventilated place to avoid mercury vapor poisoning.

5. Iron bars and copper sulfate

Principle: Put the derusting iron bar into copper sulfate solution, iron is more active than copper, and the replaced copper forms beautiful loose precipitate.

The solution is blue at first (the color of hydrated copper ions), and as the reaction progresses, the blue color gradually fades.

Trivia: Copper ion itself is not blue, and anhydrous copper sulfate is white powder. The blue color in the aqueous solution is copper ions hexahydrate.

Danger: low. Copper solution is poisonous and inedible.

6. Gas ignition

Principle: Combustion requires combustible materials to contact with oxygen, and the narrow bottle mouth makes oxygen only enter gradually, and the combustion surface moves down gradually.

Danger: medium to high. Improper handling of combustible gas can easily lead to explosion.

7. Burning magnesium is put into water.

Principle: Magnesium can actually react with water at room temperature, but unless it is magnesium powder, the speed is very slow. At high temperature, they will react violently to produce magnesium oxide and hydrogen. Hydrogen continues to burn, and together with the burning magnesium, it produces dazzling light and shadow effects.

Trivia: This reaction is the basic principle of an experimental engine designed in Japan. Magnesium oxide produced by the reaction between magnesium and water is decomposed into magnesium and oxygen again under the action of laser. The whole reaction only needs water, and the laser is powered by sunlight. However, this engine seems to be far away.

Danger: medium. Magnesium burns at high temperature and reacts violently with water, which may spill red-hot liquid magnesium and cause burns.

8. Acetone "dissolves" foam

Principle: A shallow layer of acetone can't really "dissolve" the whole foam. In fact, it just dissolves the long chain of polystyrene, allowing a lot of air in the foam to escape. Acetone can't do anything where the long chain is crosslinked, so there will be residual polystyrene at the bottom of the bowl.

Trivia: The situation of 502 glue dripping on foam is similar.

Danger: low. Acetone has certain toxicity and volatility, so it should be tested in a ventilated place and should not be drunk.

9. Blood and hydrogen peroxide

Principle: There is an efficient catalase in the blood, which can catalyze the decomposition of hydrogen peroxide into water and oxygen, and a large amount of oxygen forms a foam effect.

Trivia: Catalase is a very common enzyme, which exists in almost all aerobic organisms. In cells, its main function is to catalyze reactive oxygen species to generate oxygen and prevent oxygen from destroying cells. Catalase is also one of the most efficient enzymes, and each enzyme molecule can catalyze millions of hydrogen peroxide molecules per second.

Danger: low to medium. High concentration of hydrogen peroxide is very corrosive, but low concentration is safer. There is no other threat unless there is something wrong with your blood source. ...

10. Elephant toothpaste

Principle: The core of this reaction is the decomposition of hydrogen peroxide, just like the blood reaction in the previous paragraph. Mix 30% hydrogen peroxide with hand sanitizer, add some food coloring, and add potassium iodide as catalyst. A small amount of hydrogen peroxide can produce a large amount of oxygen, which forms bubbles under the action of soap.

The safer version is to use low concentration (3%-6%) hydrogen peroxide and dry yeast as catalysts. Raw materials are relatively easy to get, but the reaction is not so intense.

Trivia: After the reaction, a lot of oxygen will gather in the bottle. You can try to turn off the light and then throw a match in to observe the burning. Beware of fire.

Danger: low to medium. Strong hydrogen peroxide is corrosive, please wear gloves when handling.

There is another way for P.S. to do this experiment (the source has not been found yet):

1 1. The universe in the light bulb

Principle: This is a flash bulb filled with zinc wire and oxygen. It will ignite when electrified and can only be used once. The bread is covered with a plastic film in case the light bulb is broken. Before the appearance of modern electronic flash, it was the main flash prop, and it took longer to reach full brightness, but it also took longer to burn.

When this picture spread on the Internet, many people said it was the moment when the light bulb burned out. Unfortunately, ordinary tungsten light bulbs will only fade slowly when they reach their life.

Trivia: Early flash bulbs used magnesium wire, which was not as bright as zinc. Earlier, magnesium powder was mixed with potassium chlorate and ignited in an open environment. This is the origin of the word "spotlight".

In addition, many netizens said, "This is our universe".

Danger: low. The light bulb will be very hot after use. Don't touch it immediately.

12. Five lamps and ten cesium

Principle: Cesium is an active alkali metal, which reacts explosively with water to generate hydrogen. High-speed photography requires extremely strong light, and the high temperature generated by light makes cesium unable to remain solid, so ampoules are used to hold liquid cesium in the experiment. When the small hammer breaks the ampoule, cesium droplets gush out and react with water vapor and oxygen in the air, leaving traces, and large pieces of cesium explode after entering the water.

Trivia: there is such a fishing post on the internet, "... Edison is impatient to wait." He picked up the cesium block, dipped it in water, poured the spilled water into a measuring cup, measured the volume, and knew the volume of the cesium block. " Maybe this is the real reason for Edison's deafness?

Danger: high. Cesium reacts with water very violently, so pay attention to protection.

13. Zinc fire

Principle: This liquid is diethyl zinc. It is a highly flammable organic zinc compound that spontaneously ignites when exposed to oxygen. The real diethyl zinc is the blue flame as shown in the picture, but the most popular video/animation on the Internet came from the University of Nottingham in 2008. They filmed the yellow flame-according to their own statement, it was caused by sodium pollution.

Trivia: Diethylzinc was found in 1848, and it was the first organic zinc compound. It is widely used in organic synthesis and used as liquid fuel by early rocket researchers.

Danger: high. There are few good things that can spontaneously ignite, let alone liquids.

14. Volcanic eruption

Principle: The outer red powder is ammonium dichromate, which is unstable. When decomposed by heat, a large number of dark green ashes (chromium trioxide) and bright red flames can be produced.

(NH4)2Cr2O7？ (s)？ →? Cr2O3？ (s)+？ N2？ (g)+ 4？ H2O？ (g)

This effect is very similar to volcanic eruption.

Hidden inside is the "Pharaoh snake" of mercury thiocyanate introduced in the last issue.

Trivia: Ammonium dichromate is nicknamed "Mount Vesuvius" because of its effectiveness. It has applications in fireworks and early photography. Matching it with mercury thiocyanate is like summoning Cthulhu. ...

Danger: high. Ammonium dichromate is as toxic and irritating as all hexavalent chromium. Heating in a closed container may lead to explosion. Please refer to the last issue about mercury thiocyanate.

15. Aluminum meets bromine.

Principle: Aluminum is a very active metal. Because it has a dense oxide layer on its surface, it is very stable in the air, but it will react violently with many other oxidants. Bromine is one of them. The reaction of aluminum tribromide dissolved in water will also release heat, which may lead to explosion. After the experiment, the test tube must be cooled and then slowly dissolved with mild water flow. After cleaning, sodium thiosulfate solution should be added to reduce any residual bromine.

Trivia: The real form of "aluminum tribromide" is actually Al2Br6, which is very stable. Even after gasification, only a part of it will be decomposed into AlBr3.

Danger: high. Bromine is volatile, corrosive and toxic after inhalation, so protective measures are needed. Strong reaction, splashing, please be sure to start in small quantities!

16. The pillar of darkness

Principle: Black coffee will not become this thing. The cup is a mixture of p-nitroaniline and concentrated sulfuric acid, and a very complicated reaction will occur after heating-in fact, we don't fully know the detailed process of the reaction. The atomic ratio of the final black foam is C6H3N1.5S0.15O1.3, which is almost certain to be a polymer crosslinked with p-nitroaniline. The whole reaction is sometimes called "explosive polymerization". The expansion to such a large length is due to the reaction of producing gas such as carbon dioxide.

Trivia: This reaction was discovered by NASA researchers in the 1970s. They considered using it as a fire extinguishing agent at that time-because the black foam produced was very stable and had excellent heat insulation performance.

Danger: medium to high. P-nitroaniline is toxic, and concentrated sulfuric acid is also dangerous. The reaction also produces nitrogen oxides and sulfur oxides.

Don't think of p.s.' s last experiment.

17. Red and black

Principle: This is a variant of "iodine clock reaction". Add three colorless transparent solutions used in the experiment (from front to back):

1, soluble starch and sodium metabisulfite

2. Mercury chloride

3. Potassium iodate

Wherein, the reaction comprises:

1, sodium metabisulfite reacts with water to generate sodium bisulfite? Na2S2O5+ H2O？ → 2 Sodium bisulfite

2. Sodium bisulfite reduces iodate to iodide? IO3-？ + 3HSO3-→ I- + 3SO42-？ + 3H+

3. With the increase of iodine ion concentration, soluble mercury salts and iodine ions began to form mercury iodide precipitate (orange red) Hg2++ 2 I-→ HgI2.

4. The remaining iodine ions and iodate ions generate iodine? IO3-？ + 5I-？ + 6H+→ 3I2？ + 3H2O

5. Does iodine combine with soluble starch to form a blue-black inclusion compound?

Trivia: This improved version of the reaction was invented by two students of Princeton University. They added mercury salt to it, so that the reaction can form orange red and black successively. The combination of orange and black is the representative color of Princeton University. This reaction is often referred to as the "old Nassau reaction", in which "old Nassau" refers to Princeton University:

Danger: low.

24.sodium hydride

Principle: This is the reaction of sodium hydride and water to produce sodium hydroxide and hydrogen. Phenolphthalein is added to the solution as an indicator, so it appears purple.

Trivia: Sodium hydride is a very alkaline substance, which can take protons from many compounds to form corresponding sodium compounds, and is very practical in organic synthesis.

Danger: high. Sodium hydride is very active and reacts violently.

25. Aluminum iodide reaction

Principle: Mixing iodine with aluminum powder and adding a small amount of water can trigger a violent reaction. The main reaction formula: 2Al(s)+3I2(s) → Al2I6(s), in which water is used as catalyst. With the progress of the reaction, iodine will sublimate to form purple iodine vapor.

Trivia: When it comes to aluminum powder, the most impressive thing is probably the aluminothermic reaction. Let's review:

Danger: medium to high. The reaction is violent and iodine vapor is irritating. Pay attention to protecting your eyes and do it in a fume hood. After adding water, the reaction may take some time to start, so don't worry and watch carefully.

26. Golden zinc oxide

Principle: White zinc oxide powder will gradually turn golden yellow when heated to high temperature, and will fade when cooled in air. The reason of color is that zinc oxide crystal loses some oxygen atoms at high temperature, thus forming lattice defects.

Trivia: The color of many gems is also related to lattice defects, such as colored diamond.

Danger: medium to high. To observe the discoloration of zinc oxide, it needs to be heated to about 800℃ [3], and special care should be taken when using high-temperature flame.

27. Luminous ammonia luminescence

Principle: Luminol (3- aminobenzoyl hydrazine) is a commonly used luminescent chemical reagent. In demonstration experiments, the solution of hydrogen peroxide and hydroxide base (such as sodium hydroxide) is generally used as an activator, and iron-containing compounds are used to catalyze the decomposition of hydrogen peroxide. Luminol reacts with hydroxyl to generate double negative ions, which can react with oxygen generated by hydrogen peroxide decomposition to generate excited 3- aminophthalic acid, and will emit blue light when it returns to the ground state.

(Image from Wikipedia)

Trivia: It is estimated that many people have heard of luminol reagent from criminal investigation dramas or mystery novels. If the catalyst in the above reaction is replaced by iron in blood, it will become a reaction to detect trace blood.

Danger: low, attention should be paid to the corrosiveness of hydroxide and hydrogen peroxide.

28. Artificial smoke

Principle: concentrated hydrochloric acid and concentrated ammonia water are dripped on different positions of the paper in advance, both of which are highly volatile, and when they meet in the air, they will also form ammonium chloride, resulting in smoke effect.

Trivia: Another common demonstration experiment "Ammonia Fountain" shows the strong solubility of this gas in water. The ammonia gas in the bottle contacts with the water containing phenolphthalein and dissolves rapidly, which leads to the pressure drop in the bottle and the pink inverted fountain.

Danger: low, but concentrated hydrochloric acid and concentrated ammonia water are irritating, so attention should be paid to ventilation to avoid inhalation.

29. Fireball

Principle: The solid and liquid in the two mirrors on the right are potassium permanganate and concentrated sulfuric acid respectively. Here concentrated sulfuric acid shows its "dehydration", which reacts with potassium permanganate solid to produce manganese heptaoxide (permanganate anhydride). Manganese heptaoxide is an unstable strong oxide. When it comes into contact with cotton, it can react with cotton and cause combustion.

Trivia: In history, sulfuric acid was also used to light matches. The first modern match was invented by JeanChancel in 1805. Adding potassium chlorate, sulfur, sugar and other substances to the matchhead requires dipping a small bottle of sulfuric acid to trigger the reaction.

Danger: The concentrated sulfuric acid with medium and high concentration needs to be handled with extra care, protected from flammable substances, and carried out in a well-ventilated place. Permanganate anhydride is corrosive, strong oxidizing and explosive, so goggles or masks should be worn during the experiment, and only a small amount of mixture should be ensured. Do not increase the amount of reactants or react with other organic substances without authorization, because the reaction may be too intense.

30. Polymer foam

Principle: This is a reaction to produce polyurethane foam. The raw materials include isocyanate, polyol and foaming agent. Polyurethane (PU) refers to a kind of polymer with carbamate characteristic units in its main chain. Polyurethane has stable chemical properties and adjustable mechanical properties, and is widely used in industry and life. Polyurethane foam can be used as thermal insulation material.

Trivia: For example, you can experience how wide polyurethane is: most of the artificial leather products on the market are made of polyurethane, and the most common non-latex condoms are also made of polyurethane, which can also be made into sofa cushions and soles.

Danger: low, attention should be paid to avoid inhalation and contact with skin and eyes. Polyurethane foam itself is quite flammable, so many commercial products will be pre-added with flame retardants.

3 1. Dry ice and magnesium

Principle: After the magnesium rod is ignited, it is put into dry ice, and the reaction formula is 2 mg+CO2 → 2 MgO+C.

, the reaction issued a dazzling light.

Trivia: The earliest flashlights used strong light from magnesium, so they were also called "magnesium light".

Danger: high. During the reaction, sparks may be splashed, so it is necessary to remove all combustible materials nearby and use protective partitions.

32. Traffic lights

Principle: Add three ingredients to the solution in the bottle: sodium hydroxide, D- glucose and indigo carmine (or acid indigo). Indigo carmine is a redox indicator and has the function of acid-base indicator, that is, it can become a variety of colors under the action of redox reaction and pH value. Indigo carmine has three different redox states. In this reaction system, the bottle will be oxidized by oxygen in the air when shaking, and will be reduced by glucose when standing, thus causing discoloration. If the reaction is carried out in different pH environments, the color will also change. The following figure summarizes the specific color change states:

According to the content provided by the Royal Chemical Society.

Trivia: Besides indicator, indigo carmine has other uses. It is an edible pigment (E 132) and is also used in some urinary system operations.

Danger: low. Here, sodium hydroxide plays a role in adjusting pH, and a very concentrated solution is not used. Glucose and indigo carmine are also safer.

33. Layered discoloration

Principle: The orange part below the test tube is potassium dichromate solution with some sulfuric acid, and the transparent part above is ether, and some hydrogen peroxide is added to it when the reaction is initiated. Then the system will react violently, and the organic layer on it will turn blue and produce gas.

When hydrogen peroxide is added, the water phase will react as follows: K2Cr2O7+H2SO4+H2O2 → 2cro5+K2SO4+5h2o. The chromium peroxide (CrO5, also called chromium pentoxide) produced here is an unstable peroxide, which can be dissolved in ether and brings a deep blue color. Unstable chromic peroxide will continue to react to generate trivalent chromium salt: 2cro5+7h2o2+3h2SO4 → Cr2 (SO4) 3+10h2o+7o2, and the bubbles in the test tube are the oxygen generated by this reaction [1].

Trivia: Chromium peroxide is also blue in aqueous solution, but it can remain blue for a long time by ether extraction, which is convenient for observation.

Danger: medium height, intense reaction, need to wear gloves and goggles, don't fill the test tube too full.