The application of chemical knowledge in life
It plays an important role in ensuring normal physiological, biochemical activities and functions in the body. The role of Na+ and Cl- in the body is to interact with elements such as K+ are intricately connected. Its main function is to control the electrolyte balance in cells, tissue fluid and blood to maintain the normal circulation of body fluids and control the acid-base balance in the body. Na+, K+, Ca2+, and Mg2+ also help to maintain Proper stress levels for nerves and muscles; NaCl and KCl play a role in regulating the proper viscosity or consistency of the blood; acids in the stomach that begin digestion of certain foods and other digestive compounds in gastric juices, pancreatic juices, and bile are also produced in the blood It is formed of sodium salts and potassium salts. In addition, appropriate concentrations of Na+, K+ and Cl- also play an important role in the physiological process of the retina's response to light. In addition, gargling with light salt water is often used, not only for sore throat and swollen gums. It has therapeutic and preventive effects on oral diseases, etc., and also has the effect of preventing colds. (This knowledge is in "Alkali Metals" of the People's Education Edition of Gaoyi Chemistry)
Potassium iodide, sodium iodide, iodate, etc. contain Iodine compounds are important reagents in laboratories; in food and medical treatment, they are important nutrients and pharmaceuticals, playing an important role in maintaining human health. Iodine is an essential trace element in the human body and is a thyroid hormone. An important component of iodine. Normal human body tissue contains 15 mg to 20 mg of iodine, 70% to 80% of which is concentrated in the thyroid gland. Iodine in the human body exists in the form of compounds, and its main physiological effect is through the formation of thyroid hormone. occurs. Therefore, the physiological effects and important functions of thyroxine are directly related to iodine. The lack of iodine in the human body can lead to a series of biochemical disorders and physiological dysfunction, such as endemic goiter, resulting in stagnant growth and development of infants and young children. , mental retardation, etc. Our country is an area of ??severe iodine deficiency in the world. About 400 million people across the country are iodine deficient. The government has also taken some measures, such as providing iodine-containing (iodine compounds) salt and other foods (such as high-iodine eggs). ), add iodine to well water, and eat iodine-rich seafood, among which iodine-containing salt is the most convenient and effective. In March 1991, our government made a solemn commitment to the international community: to eliminate iodine deficiency diseases in mainland China by 2000. ( This knowledge can be found in "Halogen Elements" in the high school chemistry section of the People's Education Press)
Second, one of the Schisandra chinensis in life - vinegar (acid)
The chemical name of vinegar is acetic acid, and its molecular formula It is CH3COOH. Vinegar is not only a condiment, but also has many uses: 1. When cooking vegetables, adding some vinegar not only tastes delicious, but also protects the vitamin C in the vegetables (because vitamin C is not easily absorbed in an acidic environment) Destruction). 2. When cooking ribs, chicken, and fish, if you add a little vinegar, a large amount of calcium and phosphorus in the bones can be dissolved in the soup, thereby greatly improving the body's absorption rate of calcium and phosphorus. 3 , People suffering from low-acid gastric disease (too little gastric acid secretion, such as atrophic gastritis), if they often use a small amount of vinegar as a condiment, can not only increase their appetite, but also treat the disease. 4. When the fish is not fresh, Under certain circumstances, cooking with vinegar can not only remove the fishy smell, but also kill bacteria. 5. Vinegar can be used as a good medicine to prevent dysentery. Dysentery bacteria will die as soon as they encounter vinegar, so in the summer season when dysentery is prevalent, eat more vinegar. It can increase the effect of killing dysentery bacteria in the gastrointestinal tract. 6. Vinegar can also prevent influenza. Close indoor doors and windows tightly, pour vinegar into a pot and boil it until it dries, which can eliminate germs. 7. When polishing leather shoes, adding a drop of vinegar can make the leather shoes bright and lasting. 8. Copper and aluminum utensils are worn out. Rub them with vinegar and then clean them to restore their luster. 9. 20 minutes before killing the chickens and ducks, give some to the chickens and ducks. Vinegar will make it easier to pluck hair. 10. If the clothes are stained with fruit juice, soak them in vinegar and rub them off. 11. Soak the scale in the thermos bottle with vinegar to achieve the purpose of descaling. 12. Towels are prone to this in summer. Mildew causes odor. Washing the towel with a small amount of vinegar can eliminate the odor. (This knowledge is in "Derivatives of Hydrocarbons" in the high school chemistry of the People's Education Press)
Three, voluntarily smoked poison - cigarettes
From a chemical perspective, let’s introduce the structure, properties and hazards of harmful components produced during smoking. Substances harmful to the human body produced after cigarettes are lit are roughly divided into six categories: (1) aldehydes, nitrogen compounds, Olefins, these substances are irritating to the respiratory tract. (2) Nicotine, can stimulate the sympathetic nerves and cause damage to the lining of blood vessels. (3) Amines, cyanides and heavy metals, these are all toxic substances. (4) Phenylpyrene
, arsenic, cadmium, methylhydrazine, aminophenol, and other radioactive substances. These substances all have carcinogenic effects. (5) Phenolic compounds and formaldehyde, etc., these substances have the effect of accelerating carcinogenesis. (6) Carbon monoxide can reduce the ability of red blood cells to absorb oxygen. The ability to be transported throughout the body. Recent research by Japanese scholars has shown that smoke also contains "dioxins", the most toxic compounds known so far. They can cause and worsen various diseases, such as cancer, pneumonia, and tracheitis. , high blood pressure, bone hyperplasia, various cardiovascular and cerebrovascular diseases, asthma and infertility. According to information provided by the World Health Organization, about 10 million people around the world die from smoking-related diseases every year. Teenagers are growing up During the development period, the respiratory mucosa is easily damaged, and smoking is more harmful. According to surveys, people who start smoking when younger than 15 years old have a 17 times higher incidence of lung cancer than non-smokers. Therefore, the code for primary and secondary school students in China stipulates that students are not allowed to smoke. .(This knowledge runs through the organic matter in the high school chemistry of the People's Education Press)
Four. Assistant to learning - pen
1. The pencil lead is made of graphite mixed with a certain proportion of clay. When more clay is added to the pencil lead, the hardness increases, and the pen is marked with the initials H for Hard. On the contrary, the proportion of graphite increases, the hardness decreases, and the black color is enhanced, and the pen is marked with the initials Black. Write the letter B.
2. Ballpoint pen: The ink is a viscous oil made from linseed oil, synthetic pine nut oil (mainly containing terpene alcohols), mineral oil (fractionated petroleum and other minerals) The obtained oil), hard glue is prepared by adding oil smoke, etc. When using a ballpoint pen, do not write on paper with oil or wax, otherwise the oil and wax will be embedded in the copper bowl along the edge of the steel ball and affect the oil production while writing. When not writing, you must also avoid impact and exposure to the pen. Keep the pen cap when not in use to prevent damage to the pen tip, deformation of the pen barrel, and oil leakage from the pen core, which may contaminate objects. If it is cold or has been left unused for a long time, the pen should not be damaged. When the oil comes out, you can soak the pen tip in warm water for a while and then slide the pen tip on the paper to write.
3. Fountain pen: The pen tip should contain 5% to 10% of A pen made of special steel composed of Cr and Ni alloy. Chromium-nickel steel has strong corrosion resistance and is not easy to oxidize. It is a kind of stainless steel. This kind of pen has good corrosion resistance, but poor wear resistance.
< p>5. A powerful assistant in life:(1), remove stains on clothes:
Here are some simple ways to remove common stains:
p>
1. Sweat stains: Method 1: Soak clothes with sweat stains in 10% salt water for a while, and then wash them with soap. Method 2: Add a small amount of carbon amine [(NH4)2CO3 to an appropriate amount of water ] and a small amount of edible alkali [Na2CO3 or NaHCO3], stir and dissolve, soak the sweat-stained clothes in it for a while, and then rub it repeatedly. 2. For oil stains, drop gasoline or alcohol on the oil stains, wait until the gasoline (or alcohol) The oil stains will also disappear after evaporating. 3. Blue ink stains: Method 1: Add a small amount of carbon amine [(NH4)2CO3] and a small amount of edible alkali [Na2CO3 or NaHCO3] to an appropriate amount of water, stir and dissolve, then Soak the clothes stained with blue ink for a while, and then rub them repeatedly. Method 2: Soak the area stained with blue ink in 2% oxalic acid solution for a few minutes, and then wash it off with detergent. 4. Blood stains are caused by blood It contains protein, and the protein is not easily dissolved when heated, so hot water cannot be used to wash blood stains. Method 1: Soak the blood-stained parts in hydrogen peroxide or bleaching powder water for a while, and then scrub. Method 2: Chop the radish and sprinkle with salt Stir evenly, squeeze out the radish juice after ten minutes, soak the blood-stained area in the radish juice for a while, and then scrub. 5. Juice stains: Soak newly stained juice stains with salt water, and then scrub with soap. If stained, If it takes a long time, you can use Method 1 for cleaning sweat stains. 6. Rust stains: Add a little oxalic acid to hot water, stir to dissolve all the oxalic acid, and soak the area with rust stains in the oxalic acid solution for ten minutes. Then wash it with soap. 7. Tea stains: Soak the area with tea stains in saturated salt water, and then wash it with soap.
(2) How to descale the kettle
1. Put the empty kettle on the fire and boil away the water in the scale. When you see cracks in the scale on the bottom of the kettle, quickly remove the kettle and place it in cold water. The scale on the bottom of the kettle will fall off due to thermal expansion and contraction. 2. While burning, Put a ball of mask cloth in the water pot. The scale will be absorbed by the mask cloth, and scale will not easily form on the pot. 3. If there is scale in the pot of boiling water, you can put some vinegar and add water.
Boil for a while, and the scale can be removed. 4. When boiling water in an aluminum kettle, put a small spoonful of baking soda and boil for 10 minutes, and the scale can be removed.
(3) Quickly expand steamed buns
p>Add appropriate amounts of white vinegar (CH3COOH) and soda (Na2CO3) to the flour to produce carbon dioxide gas to make the steamed buns swell, soft and delicious. Please think about the chemical reaction
In addition, through In high school chemistry theory, you can also identify "real silk" and "rayon", identify true and false gold and silver, preservatives in food, disinfection effects of alcohol and phenol, etc.
In short, chemistry is everywhere in life. .The key lies in whether we pay attention to observation and learn knowledge in life. In the future, let us continue to accumulate knowledge for "Application of High School Chemistry Theory in Life".
Application of Physics Common Sense in Life
p>Decades of teaching experience in junior high schools have made me realize that the characteristic of physics teaching in junior high schools is that it is difficult for students to learn. Abstract physical knowledge can only be combined with practice and the reality of life to turn it into a vivid reality of life. Only in this way can students master knowledge effectively. For example, in the vaporization section of the chapter on changes in the state of matter, the physical laws are explained clearly, that is: evaporation and boiling are two ways of vaporization. The former can only proceed slowly on the surface of the liquid and can occur at any temperature, while boiling is a violent vaporization phenomenon that occurs simultaneously on the surface and inside the liquid and can only occur at a certain temperature. The only thing they have in common is that they need to absorb heat. Vaporization is a ubiquitous phenomenon in nature, closely related to the reality of human life, and has widespread applications in production and life. Students, do you know the following principles?
1. Why can water extinguish fire?
When a fire breaks out, firefighters often use water to extinguish the fire. What role does water play in extinguishing the fire?
First of all, as soon as water contacts a hot object, it will immediately heat up and vaporize into water vapor. We know that vaporization needs to absorb heat and absorb a large amount of heat from the hot object. When cold water is heated to 100 degrees Celsius, it needs to absorb heat. The heat absorbed by boiling water into water vapor is more than five times the heat absorbed by the same mass of cold water heated to 100 degrees Celsius, thereby cooling down and extinguishing fires.
Secondly, the volume of water vapor is hundreds of times larger than the volume of water of the same mass. With so much water vapor surrounding the burning body, the burning body cannot fully contact the air, making combustion difficult. .
It must be noted here: not all fires can be extinguished with water. For example, oil fires must not be extinguished with water, but can only be extinguished with carbon dioxide foam fire extinguishers or other air-isolating methods.
2. The temperature is not necessarily determined by the temperature.
Some students may say: Who doesn’t know that high temperatures make it hot and low temperatures make it cold. But this is not always the case. We all have this experience: it is colder when there is wind in winter. What is the reason? If you put the thermometer in the wind, the temperature of the gas will not drop. On cold days, people feel particularly cold in the wind. First of all, the heat dissipated from the exposed parts of the human body, such as the head, face, and hands, is much more than when there is no wind. This alone is enough to cause us to feel cold. .
But there is another important reason. Our skin is evaporating water all the time, and evaporation absorbs heat and has a cooling effect. Students can do such a small experiment. Apply a little alcohol on the back of your hand and blow it with your mouth. You will feel particularly cool. In windy weather, the water on the skin surface evaporates quickly and absorbs more heat from the body, so you feel colder.
Based on the above principles, people have adopted many insulation and cooling measures in production and life. Here are a few examples: 1. Patients with high fever or heat stroke use physical cooling, that is, on the patient’s forehead and other Apply alcohol to the skin so that it absorbs heat from the body and reduces fever. 2. Sprinkling water in the classroom in summer uses water evaporation to cool down and dissipate heat. 3. In the cold winter, people often close the doors and windows, while in the summer they keep the indoor air flowing. 4. It is best to use a hair dryer to dry your hair after washing your hair in winter. If you let it dry naturally, it will absorb a lot of heat from your head and you may catch a cold. 5. The rocket head is coated with a layer of special material. This material melts and vaporizes at high temperatures. Both melting and vaporization absorb heat, so that the temperature of the rocket will not be too high and it will not be burned.
3. The temperature of boiling water, that is, the boiling point, is not always 100 degrees Celsius.
The temperature of boiling water is related to the air pressure. We know that atmospheric pressure decreases with increasing altitude.
For every 300 meters of altitude increase, the boiling water temperature, or boiling point, decreases by 1 degree Celsius. According to this calculation, if water is boiled on Mount Everest, the water will boil at around 70 degrees Celsius. On the contrary, in a mine 1000 meters below sea level, the boiling point of water is 103 degrees Celsius. In a steam boiler with 14 atmospheric pressure, the boiling point of water is 200 degrees Celsius. Therefore, it should be said that under a standard atmosphere, the boiling point of pure water is 100 degrees Celsius. Food cooked in high mountains is not easy to cook. In order to cook food, mountain residents often press stones on the lid of a closed pot. Increasing pressure increases boiling point. Modern people have invented and widely used pressure cookers. The pressure inside the pot is above 1.2 atmospheres. It can be used in any area. The temperature of the pot is well over 100 degrees Celsius. It is much faster and more convenient to cook food. In the sugar industry, similar methods are used to reduce the boiling point, which not only saves fuel and improves production efficiency, but also ensures that the sugar will not deteriorate due to excessive temperature.
In addition, adding some acid, alkali, salt and other substances to the water will also increase its boiling point. Therefore, when cooking food, add a little salt, and the food will be cooked easily.
4. When cooking food, does the hotter the fire, the faster?
Some people think that in order to cook food as quickly as possible, just burn a bigger fire. The result is that the purpose is not achieved. Because the temperature of water does not change when it boils, even if the fire power is increased, the water temperature cannot be increased. The result is only to accelerate the vaporization of the water and make the water in the pot dry out quickly, which is a waste of fuel. The correct method is to use high heat to boil the water and then switch to low heat to keep the water in the pot boiling.