Fun chemistry experiments

"Coke" becomes "Sprite"

Coca-Cola and Sprite are both ideal drinks during the summer season. Coca-Cola is a light brown liquid, while Sprite soda is a clear and transparent liquid. Here is a small experiment to turn "Coca-Cola" into "Sprite".

Take an empty Coca-Cola bottle and pour three-quarters of the volume of distilled water into it. Take a beaker, add 50 ml of alcohol, and add an appropriate amount of iodine tablets to prepare a dark brown alcohol-iodine solution. Pour the prepared solution into the Coke bottle and shake the iodine while adding it until the color of the solution is similar to that of Coke. A bottle of "Coke" is ready. Put sodium thiosulfate (sodium thiosulfate) powder into the dry bottle cap, then take a piece of glutinous rice paper and cover it with the powder, then gently cover the bottle mouth with the bottle cap, be careful not to let the big Soda powder is scattered inside the bottle.

Shake the Coca-Cola bottle hard, and soon a bottle of "coke" turns into a colorless and transparent "sprite".

It turns out that sodium sulfate and iodine can undergo oxidation-reduction reactions to remove the color of the iodine solution:

I2+2Na2S2O3===2NaI+Na2S4O6

Naturally, this "Coca-Cola" will not be palatable, nor will the "Sprite" be refreshing, they are absolutely not drinkable.

Color-changing handkerchief

Before teaching a new lesson, the chemistry teacher made an interesting chemistry magic trick for the students. There was a green glass bottle with a small mouth on the podium. The teacher was holding two new bright red handkerchiefs. He dipped them in tap water, took them out and twisted them. Then he said to everyone: "I can put them The two red handkerchiefs turned into yellow and white." Then, put the two handkerchiefs into the bottle and cover it with a piece of cloth. After waiting for a moment, the teacher deliberately said loudly: "Change", lifted the cloth, opened the bottle cap, and methodically took out a yellow handkerchief. He closed the bottle again, and after a while, he took out another white handkerchief from the bottle. The students all looked at the teacher with exploratory eyes, what on earth is going on?

Answer

It turns out that the bottle is filled with green chlorine gas. Chlorine atoms are a very active non-metallic element. Dry chlorine is not very reactive at low temperatures, but in the presence of trace amounts of water, the reaction accelerates dramatically. The reason is that chlorine gas easily dissolves in water to form hydrochloric acid and hypochlorous acid. Hypochlorous acid is very unstable and easy to decompose. The oxygen it releases is a very strong oxidant. Therefore, the wet red handkerchief gradually oxidizes to yellow, and then from yellow to white. This is the discoloration effect of chlorine. This important property of chlorine has been widely used in industry, such as the familiar bleaching powder. What needs to be explained here is that chlorine is a toxic gas with a strong suffocating odor and strong irritation to the respiratory organs, so you should be careful.

The glass rod ignited the ice cubes

The glass rod can ignite the ice cubes. You must have thought it was a joke. However, what I said is completely true. Ice cubes can burn, which will surprise people, and what is even more surprising is that without matches or lighters, just tap lightly with a glass rod, and the ice cubes will burn immediately and will not go out for a long time. If you are interested, you can do an experiment and see. First, pour 1 to 2 small grains of potassium permanganate in a small dish, grind it gently into powder, then add a few drops of concentrated sulfuric acid, stir evenly with a glass rod, dip the glass rod in this mixture , is an invisible small torch that can light alcohol lamps and ice cubes. However, put a small piece of calcium carbide on the ice cube in advance, so that as long as you lightly touch the ice cube with a glass rod, the ice cube will burn immediately. Readers are asked to give their answers after experimenting.

The reason is simple. The calcium carbide on the ice (the chemical name is calcium carbide) reacts with a small amount of water on the ice surface. The calcium carbide gas (the chemical name is acetylene) generated by this reaction is a flammable gas. Since concentrated sulfuric acid and potassium permanganate are both strong oxidants, they are enough to oxidize the calcium carbide gas and immediately reach the ignition point, causing the calcium carbide gas to burn. In addition, since the reaction between water and calcium carbide is an exothermic reaction, and the combustion of calcium carbide gas releases heat, The ice melts into more and more water, so the calcium carbide reaction becomes faster and more calcium carbide gas is produced, and the fire becomes more and more prosperous.

Tea - ink - tea

On Sunday, classmate Xiaoming and her father watched a magic show at the Municipal Workers' Cultural Palace. One of the programs was: tea turns into ink. Ink turns into tea.

The magician on the stage was holding a cup of brown tea in his hand. He stirred the tea with a glass rod and shouted "Change". At this time, the tea immediately turned into blue ink. Then, this The magician stirred the other end of the glass rod in the ink cup and shouted "change". Sure enough, the blue ink that had just been turned into the original tea again. What a wonderful performance! Full of praise. But he couldn't figure out how it changed. Please help him figure out the reason.

It turns out that the end of the glass rod is a very interesting chemical reaction. Dip in green vitriol (chemical name is ferrous sulfate) powder in advance, and dip the other end in oxalic acid crystal powder. Because the tea contains a lot of tannic acid, when the tannic acid encounters the ferrous ions in the green vitriol, it will immediately react. Ferrous tannic acid is generated, which is unstable in nature and is quickly oxidized to form an iron tannic acid complex that turns into a blue-black color, thus turning the tea into "ink". Oxalic acid has reducing properties and converts trivalent iron into iron. The iron ions are reduced to bivalent ferrous ions, so the blue-black color of the solution disappears and the color of tea appears again. This phenomenon is also often encountered in people's lives when you use a knife to cut unripe fruits. Sometimes, we often see a blue color on the cutting edges of fruits. Some people think that it is caused by the unclean knife. In fact, this situation is the same as the above-mentioned tea turning into ink. It is caused by the iron on the knife and the tannin on the fruit. The result of chemical reaction

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