1. Use of iodized salt. Iodine is an essential nutrient for human body, and long-term iodine deficiency will lead to iodine deficiency. Edible iodized salt is the simplest, economical and effective method to eliminate iodine deficiency. Iodized salt contains sodium chloride and potassium iodate, which provides iodine for human body. Potassium iodate is unstable and easy to decompose when heated and illuminated, thus affecting the human body's iodine intake. So pay attention when cooking: add salt as soon as you cook it, and don't stew it for too long.
2. Don't cook tofu with spinach. Calcium oxalate is a precipitate that the human body cannot absorb. Spinach, onion and bamboo shoots are rich in oxalic acid and sodium oxalate, and tofu contains more calcium salts, such as calcium sulfate. The above substances can undergo a metathesis reaction to generate calcium oxalate precipitation and other substances. From a medical point of view: spinach, onions, bamboo shoots, etc. It is not suitable to mix with tofu at the same time, which will produce calcium oxalate precipitation, which is the cause of stones; From a nutritional point of view, mixed eating will destroy their nutrients.
3. The harm of aluminum to human health. Aluminum has always been considered as a non-toxic element, so aluminum drinking utensils, baking powder containing aluminum expansion agent and water purification agent are widely used. However, recent studies show that aluminum can disturb human metabolism and cause long-term and slow harm to human health, and its toxicity is slow and difficult to detect. However, once the toxic reaction of metabolic disorder occurs, the consequences will be serious. To prevent aluminum poisoning, we should pay attention to (1) reducing the entry route of aluminum, such as eating less fried dough sticks, and avoiding aluminum hydroxide as much as possible in stomach drugs. (2) Eat less food packaged in aluminum products. (3) Use aluminum products appropriately to avoid long-term contact between food or drinking water and aluminum products.
4. Why can fruit sober up? This is because fruits contain organic acids, for example, apples contain malic acid, oranges contain citric acid, and grapes contain tartaric acid. The main component of wine is ethanol, and organic acids can interact with ethanol to form esters, thus achieving the purpose of sobering up. Similarly, vinegar can relieve alcoholism because it contains 3-5% acetic acid, which can react with ethanol to produce ethyl acetate.
5. It is not advisable to burn oil and smoke when cooking. When oil is at high temperature, polycyclic compounds are easily formed. Generally, vegetable oil contains more unsaturated fatty acids, which makes it easier to form polycyclic compounds. Experiments show that polycyclic compounds are easy to induce animal bladder cancer. Generally, as long as the oil is boiled, the "internal heat" of the oil can be removed.
6. Why is there a "red tide" in seawater? In recent years, a large area of red tide has appeared in China's Bohai Bay and other offshore areas, which is called "red tide". Red tide is not a tidal phenomenon, nor is it a current movement like Kuroshio, but a biological phenomenon of red plankton overgrowth in the ocean under certain conditions. Why can plankton multiply in large numbers? It turns out that a large number of wastewater, waste residue and substances that enter the ocean through atmospheric exchange contain elements such as nitrogen and phosphorus, which are essential nutrients for plant growth. So a large number of plankton proliferated rapidly, making the sea wear "red clothes". In order to prevent the red tide in the ocean, we should control the discharge of wastes containing nitrogen and phosphorus into the ocean, such as wastewater containing phosphorus washing powder, so as to maintain the ecological balance in the ocean.
7. pH of food. Studies have found that eating more alkaline foods can keep blood weakly alkaline, reduce acid substances such as lactic acid and urea in blood, and prevent them from depositing on the blood vessel wall, thus softening blood vessels. Therefore, some people call alkaline food "a cleaner for blood and blood vessels". Generally speaking, rice, noodles, meat, fish and eggs are almost all acidic foods, while vegetables, fruits, milk, sweet potatoes, potatoes, bean products and aquatic products are all alkaline foods. Pay attention to scientific diet, improve diet structure, strengthen physical exercise and develop good living habits, and arteriosclerosis is expected to be delayed and reversed. The pH of human body fluids is closely related to IQ level. Within the allowable range of body fluid pH, people with high acidity have lower IQ, while people with high alkalinity have higher IQ. Scientists tested dozens of boys aged 6 to 13. The results show that the IQ of children whose body fluid PH is greater than 7.0 is higher than that of children whose body fluid pH is less than 7.0 1 times. Some children with poor academic performance and low level of intellectual development are often acidic.
8. Sulfur dioxide in food. Sulfur dioxide is a very important member of inorganic chemical preservatives. Sulfur dioxide has been used as a food additive for centuries, and the earliest record is that it was used to disinfect wine containers in Roman times. Later, it was widely used in food, such as sulfur fumigation in the manufacture of dried fruits and preserved fruits; Preparation of sulfur dioxide sustained-release agent for fresh-keeping storage of grapes and other fruits. Sulfur dioxide can show many technical effects in food, which is generally called bleaching agent, because sulfur dioxide can react with colored substances to bleach food. On the other hand, sulfur dioxide can reduce the activity of oxidase, thus inhibiting enzymatic browning. In short, because the application of sulfur dioxide can make dried fruits and preserved fruits have beautiful appearance, some people call it cosmetic additive. Sulfur dioxide not only plays a cosmetic role, but also has many non-cosmetic functions such as anti-corrosion and anti-oxidation, which is necessary to maintain the nutritional value and quality of food. For a long time, people have thought that sulfur dioxide is harmless to human body, but since Baker et al. found in 198 1 that sulfite can induce asthma recurrence in some asthma patients, people have re-examined the safety of sulfur dioxide. After a long-term toxicological study, people think that sulfite preparation is harmless to most people at the current dose. There are two other points to note: sulfite in food must reach a certain dose to cause allergies. Even people who are very sensitive to sulfite are not allergic to all foods treated with sulfite. From this point of view, sulfur dioxide is a relatively safe preservative.
9. Why does salt deliquesce? How to make it not deliquescent? Magnesium chloride is usually contained in salt. Magnesium chloride deliquesces in air. In order to prevent salt deliquescence, salt can generally be put in a pot for dry frying. Magnesium chloride is completely hydrolyzed at high temperature to produce magnesium oxide (MgO), so it loses deliquescence. Or purify the salt, and the pure sodium chloride does not deliquesce in the air.
10, scaling. There is calcium bicarbonate dissolved in water, which can't be seen at all However, when the water containing calcium bicarbonate is put into the pot for combustion, the calcium bicarbonate is decomposed one by one after being heated, and then converted into the original carbon dioxide, water and calcium carbonate. When these boiled water containing calcium carbonate is put into a teapot or thermos bottle, calcium carbonate will gradually penetrate into the bottom of the bottle or adhere to the inner wall. After a long time, calcium carbonate will become "tea dirt". So why can hydrochloric acid remove calcium carbonate? This is another chemical reaction that produces a new substance called calcium chloride. Calcium chloride can be dissolved in water, so it will be gone as long as it is washed with water. This removes the "tea dirt". Remove "tea dirt" with hydrochloric acid. Note: first of all, don't wipe it directly by hand. It is best to scrub with copper wire wrapped in cloth. Secondly, hydrochloric acid should be diluted, not too thick or too much, because hydrochloric acid is corrosive. After removing the "tea dirt", it is necessary to wash it carefully with water several times before removing hydrochloric acid; Or put some water in the teapot and some nails. After a few days, the residual hydrochloric acid will be gone.
1 1. What medicine does the doctor use to make athletes quickly eliminate pain? When watching a football match, sometimes you will see a football player who is fighting on the field, suddenly falling down because of injury, and sometimes his thigh will roll with pain. In order to keep him struggling, the doctor ran over, took a small watering can, sprayed a medicine on the injured part, and then rubbed and massaged with cotton wool. After a while, the injured athlete stood up again and took part in the competition again. What medicine does the doctor use to make athletes quickly relieve pain? It turns out that the watering can is filled with chloroethane (C2H5Cl), which is a colorless and volatile liquid (boiling point 13.l℃). Spray on the injured part and evaporate immediately. When it volatilizes, it absorbs heat, so that the skin surface temperature suddenly drops and the feeling becomes dull, thus playing the role of analgesia and local anesthesia. This is medicine? Quot Cryopreservation "therapy.
12. Why does the wine taste better as it ages? Ordinary wine, why did it become a fine wine after being buried for a few years? The main component of wine is ethanol. After the liquor was buried underground for several years, ethanol reacted with acetic acid, a less component in liquor, and the generated CH3COOC2H5 (ethyl acetate) was fruity. Although the above reaction is reversible and the reaction speed is slow, the longer the time, the more ethyl acetate is produced, so the older the wine, the more fragrant it is.
13. How are the labels of pencils divided? The refill of a pencil is made of graphite and clay in a certain proportion. "H" is the prefix of "Hard" in English, which stands for clay and is used to indicate the hardness of pencil lead. The larger the number before "h" (such as 6H), the harder the pencil lead, that is, the greater the proportion of clay mixed with graphite in the refill, the less obvious the written words, which is often used for copying. "B" is the prefix of "black" in English, which stands for graphite, and is used to express pencil lead's softness and the obvious degree of writing. With "6B" as the softest and blackest handwriting, it is often used in painting, while ordinary pencils are generally marked as "HB". The pencil label used to paint the answer sheet during the exam is generally "2B".
14 As the saying goes: "Good medicine tastes bitter", what is the basis? Many traditional Chinese medicines contain some bitter active ingredients, such as coptis chinensis containing coptisine and ephedra containing ephedrine, so there is a saying that "good medicine tastes bitter".
15, accidentally broke the thermometer, how to deal with it? Generally speaking, a thermometer is full of mercury. If the thermometer is accidentally broken and mercury leaks out, the spilled mercury will be scattered on the ground and in the air, causing environmental pollution and endangering human health. Therefore, after the thermometer breaks down, the spilled mercury should be properly disposed of. Firstly, absorb the larger particles of mercury with a straw, and then sprinkle some sulfur powder on the remaining fine particles of mercury. Mercury reacts with sulfur to produce non-volatile mercury sulfide, thus reducing the harm.
16, why can't I drink tea and take medicine? Drugs are usually taken with warm boiled water. Why not use tea? Tea contains tannic acid, which will react with various components in the medicine, thus reducing the efficacy and even failing. For example, iron taken by anemia patients will react with tannic acid to form iron tannic acid, which is difficult to be absorbed by the human body.
17. Why should antibiotics be taken after meals? Antibiotics are mostly amine compounds, which are easily decomposed by gastric acid in the stomach after being taken on an empty stomach, which not only reduces the efficacy, but also has a great stimulating effect on the stomach wall. When taking medicine after meals, because gastric acid is diluted by food, the medicine will not be decomposed by gastric acid, so antibiotics are generally taken after meals.
18. What are the "gold powder" and "silver powder" used to draw decorative patterns made of? "Gold powder" is made of brass (copper-zinc alloy). Brass sheet and a small amount of lubricant are crushed and polished to make "gold powder", which is widely used in paint and ink. "Silver powder" is made of aluminum, which is cheap and has the same silver luster as silver. Aluminum powder is light in weight, stable in air and highly reflective. There are two ways to make aluminum powder: one is to mix pure aluminum flakes with a small amount of lubricant and crush them mechanically; The other is to melt pure aluminum into liquid and spray it into fine aluminum powder.
19, the bulb turned black after a long time, because the tungsten wire heated and evaporated and touched the cold bulb wall; Aluminum pot turned black for a long time because iron salts in water replaced aluminum; Without a drying knife, the surface will turn blue when it is dried on a fire, because iron and water combine to form ferroferric oxide.
20. When a man shaves, he can use toothpaste instead of soap. Because toothpaste does not contain free alkali, it is not only non-irritating to the skin, but also rich in foam and fragrant, making people feel cool.
2 1, turn off the fire as soon as the tap water is boiled, which is harmful to health. After boiling for 3-5 minutes, the content of nitrite, chloride and other toxic substances in the boiled water is at the lowest level, which is most suitable for drinking.