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Chemistry and Chemists № 2 2024 Journal of Chemists-Enthusiasts |
Plants as acid-base indicators - part 20, 21 Volodymyr M. Viter |
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Radish (Raphanus sativus), ammonia and acetic acid - part 20
After experimenting with flowers and leaves of various plants, I remembered that there are also root vegetables. In the supermarket, my attention was drawn to radishes - a plant of the Radish genus (Raphanus) of the Brassicaceae family, which is grown as a vegetable worldwide. We eat radish roots raw or use them to make salads. I read that radish leaves are also eaten but this is not practised in Ukraine. The colour of the root of radishes can vary, in our case it was red.
Редис (Raphanus sativus), аммиак и уксусная кислота - часть 20 I placed the radish root in a glass and added a concentrated ammonia solution. And then the unexpected happened. Typically, it takes tens of seconds or minutes for plant parts to change colour when exposed to ammonia. Sometimes this process takes tens of minutes. But when I added an ammonia solution to a glass with the radish, the surface of the root vegetable almost immediately changed colour and became dark purple (nearly black). Then the surface began to lighten slowly and unevenly. Before the experiment, the colour of the root crop was almost uniform, but now different surface areas had different colours. Some areas have turned brown. The ammonia solution turned yellow. I repeated the experiment with other radish roots, the result was similar. I took the radish roots from ammonia and left them in the air. The surface of the radishes turned dark, red-violet over time. I placed two new radish roots in a glass and added glacial acetic acid. The colour of the surface almost did not change, either immediately or over time. The acid turned light brown (similar to an ammonia solution). |
![]() Radish (Raphanus sativus) |
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![]() Radish (Raphanus sativus), ammonia and acetic acid |
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Red poppy (Papaver rhoeas), ammonia and acetic acid - part 21
The red poppy (Papaver rhoeas) is one of the most beautiful and recognizable plants in our country. Poppies are often mentioned in folklore; red poppy flowers are depicted by artists on canvases, wall paintings, and traditional embroidered clothes. In addition to their aesthetic value, poppies have culinary uses. Poppy seeds are used in traditional Ukrainian cuisine to prepare various dishes, such as buns with poppy seeds, pies with poppy seeds, and kutya with poppy seeds...
Красный мак (Papaver rhoeas), аммиак и уксусная кислота - часть 21 ![]() Of course, poppy is known to the general public not because of its beautiful flowers or delicious dishes, but primarily because the plant contains physiologically active alkaloids that can cause euphoria and eliminate acute pain. The problem is that after using these alkaloids several times, an acute drug addiction develops. A mixture of poppy alkaloids called opium has been a traditional drug in several countries since ancient times. The most famous poppy alkaloid is morphine (morphine), which is acylated to produce an even stronger drug, heroin. In the past, morphine and heroin were successfully used as effective pain relievers (morphine is still used when the patient is in severe pain), but the cost of pain relief is rapid drug addiction. In our country, people from time immemorial have been using traditional drugs, first alcohol, later tobacco appeared, but not opium. The physiological effect of poppy pods and stems in Ukraine was known, but mass drug addiction did not arise. Of course, there were cases of drug addiction to opium alkaloids or opium poisoning, but they were not widespread. For example, a case is described when a mother used to give a decoction of poppy straw to a small child so that he would not scream and sleep peacefully. As a result, once the child fell asleep and never woke up. Everything changed when the government of the Soviet Union decided to invade Afghanistan. Ukraine at that time was occupied by Moscow, so our men were massively drafted into the army for someone else's war to kill people in Afghanistan. Ukrainians who ended up in Afghanistan discovered that the locals did not drink alcohol (as we do) because they had their traditional drugs, primarily opium and hashish (cannabis). Those who survived the war and returned home brought with them the habit of using opium (morphine, heroin) and smoking cannabis. As a result, opium addiction increased sharply, and poppy cultivation came under strict restrictions. The Soviet Union's invasion of Afghanistan failed long ago, many years have passed, but the use of poppy alkaloids is not going away - the genie is out of the bottle. Nowadays in Ukraine, poppy can be found mainly growing wild or in small flower beds. I do not think it is legal to grow poppies in flower beds, but now we are at war - Ukraine in 2022 shared the fate of Afghanistan in 1979, so the police do not care about poppies in flower beds. Poppy flowers come in colours: red, orange-red, pink and white. I decided to experiment with red flowers. I remembered that poppies grew in the field near my former work and they were just blooming now, but the trip would take a long time. Suddenly I noticed a flower bed with red poppy flowers not far from the house. I decided to return here a little later to pick some flowers for experimentation. Later there was hail, and the size of the hailstones was several centimetres (this happens in our area, but rarely - not every year). Fortunately, one flower survived - I took it for experiments. Looking ahead, I will say that this was one of the rare cases when I correctly guessed how the colour of the flower's pigment would change before the experiment. I placed the red poppy flower in a glass and added a concentrated ammonia solution. First, dark spots appeared on the flower - in places where drops hit. Then the spots began to unite into dark purple zones. After a few minutes, the entire flower turned dark purple. The colour transition was very contrasting. I thought the purple flower would eventually turn yellow or brown, but that did not happen. I took the flower out of the glass, rinsed it with water and placed it in another glass. Then, I added glacial acetic acid. A lot of white smoke was produced and the plant tissue showed signs of degradation. The flower turned orange-red (its colour was similar, but not identical to the original). Acetic acid turned red-orange. I poured the red-orange liquid into a test tube and added a concentrated ammonia solution. White smoke formed again. You would expect the liquid to turn purple, but the solution turned green-yellow and then yellow. I believe that the yellow colour is due to oxidation of the pigment of poppy flowers by atmospheric oxygen in an alkaline environment. Poppy petals probably contain antioxidants that slow down the oxidation process in the flowers themselves, which is why the flowers remain purple. After extracting the pigment with acetic acid and adding ammonia, oxidation in the solution occurred quickly. |
![]() Red poppy (Papaver rhoeas), ammonia and acetic acid |
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![]() Kutya / кутя |