Common sense about physical and chemical life phenomena

1. Physical and chemical phenomena in life

Physical phenomena: (1) When sitting in a fast-moving car, when turning, you will feel thrown outward. This is centrifugal Phenomenon.

(2) The working principle of nail clippers, scissors, and tweezers is lever. (3) Tweezers, chopsticks, scissors, etc. used by people (4) The car cannot stop immediately after braking and the passengers on the train fall forward (5) Use a heavy object during construction to see if it is parallel to the wall (6) Hang it on the wall When the quartz clock on the wall stops moving because the battery is exhausted, its second hand often stops at the "9" position on the dial.

This is because the second hand is most hindered by the gravity moment at the "9" position. (7) Sometimes when the water pipe is discharging water from a nearby faucet, bursts of sound occasionally occur.

This is because the water pipes vibrate when water rushes out of the faucet. (8) The "combustion" of electric furnaces is the conversion of electrical energy into internal energy, which does not require oxygen. Oxygen can only oxidize the electric furnace wires and shorten their service life. Chemical phenomena: What to do if copperware becomes dark? Copperware will "rust" if left in the air for a long time. ".

Copper will be oxidized into black copper oxide in humid air. The copper oxide on the surface of the copper continues to interact with carbon dioxide in the air to generate a layer of green basic copper carbonate CuCO3·Cu(OH )2. In addition, copper will also interact with hydrogen sulfide in the air to produce black copper sulfide.

Use cotton dipped in strong ammonia to scrub the surface of dull copperware, and it will immediately shine. Because the surface of the copperware is scrubbed with concentrated ammonia, copper oxide, basic copper carbonate and copper sulfide will be converted into soluble copper-ammonia complex and removed.

Or scrub with acetic acid to convert the dirt on the surface into soluble copper acetate, but this effect is not as good as the former. After washing, rinse the copperware with clean water, and the copperware will be shiny again. 2. What to do if silverware becomes dark? The principle of darkening of silverware is similar to that of bronze. It is the result of the interaction between silver and hydrogen sulfide in the air to produce black silver sulfide (Ag2S).

To make silverware brighter, you must first wash away the oil stains on the surface with washing powder, put it together with aluminum sheets, put it into sodium carbonate solution and cook it until the silverware returns to silvery white, then take it out Silverware, after washing it with water, you can see that the surface of the silverware is as bright as new. The chemical equation of the reaction is as follows: 2Al 3 Ag2S 6 H2O=6 Ag 2 Al(OH)3 3 H2S 3. Adhesives for plastics and plexiglass Plastic products often appear in daily life. What should I do if plastic products are damaged? There are generally two types of plastic products, one is made of polyvinyl chloride, which is harder and brittle, and the other is made of polyethylene, which is softer.

Plexiglass is polymerized from methyl methacrylate. The best solvent for PVC is tetrahydrofuran.

The available solvents for organic glass include chloroform (chloroform), dichloroethane and acetone. When bonding, you can directly use these solvents to bond plastic or organic glass, or dissolve a small amount of plastic or organic glass in the solvent to make an adhesive, which will have better results.

4. The knowledge of lime coating on walls When lime is melted, the cold water will become hot. After the lime is painted on the wall, it is not easy to dry, and the lime wall is getting harder and whiter. Why? When lime is turned, quicklime reacts with water to form hydrated lime. This reaction is an exothermic reaction, so cold water will become hot. The reason why lime painted walls are difficult to dry is because slaked lime [calcium hydroxide] reacts with carbon dioxide in the air to produce calcium carbonate and water.

There is less carbon dioxide in the air and the reaction is slower. In addition, the formation of water also makes the wall more difficult to dry. When coating walls, the lime slurry is calcium hydroxide, which is soft. The calcium carbonate generated after reacting with carbon dioxide is hard and white. Therefore, when the calcium hydroxide is completely converted into calcium carbonate, it becomes hard and white.

5. Why does ink precipitate? Ink is a colloid. When the ink bottle is not capped properly, as the water evaporates, the ink becomes thicker, and the pigment particles are easily squeezed together. Since the water layer between them becomes thinner, the particles will combine into large particles and precipitate.

In addition, mixing different brands of ink will also cause ink precipitation. Because the colloidal particles are charged during manufacturing to stabilize them, and the charges on the colloidal particles of inks produced by different methods may be the same or different.

When inks with different charges on colloidal particles are mixed, the charges disappear due to neutralization, and the colloidal particles become unstable and precipitate. Knowing this, it is best to use another brand of ink. Rinse the pen with clean water. In addition, overcooling or overheating will also destroy the colloidal solution in the ink, causing precipitation.

Therefore, ink should be placed on the window in winter, and ink should not be placed in high temperature places at ordinary times. 6. Why can alum be used to purify water? Our ancestors have long used alum to purify water.

Alum-treated water can remove 70---90% of suspended solids and bacteria. There are many tiny colloidal particles suspended in the water. The mud colloidal particles can absorb anions and are negatively charged. After alum is added to the water, positive trivalent aluminum ions neutralize the negative charge of the mud and sand colloidal particles, thus making them unstable. As it settles, the water becomes clear.

7. The source and removal method of "scale". In kettles that have been used for a long time, there is a layer of gray-yellow sediment on the boiler wall. Where does it come from? We know that there are many inorganic salts dissolved in water, such as calcium bicarbonate, magnesium bicarbonate, and small amounts of calcium and magnesium salts such as calcium sulfate and calcium chloride. When heated, bicarbonate easily decomposes to form carbon dioxide and carbonate, and carbon dioxide escapes into the air. Calcium carbonate is difficult to dissolve in water, and magnesium carbonate is slightly soluble in water, so it precipitates. In kettles and boilers that have been used for a long time, With "scale".

"Scale" has poor thermal conductivity. Boiling water with kettles and boilers containing "scale" will cause a waste of energy. For factory boilers, when the "scale" accumulates thickly, part of it will automatically peel off. , uneven heating of various parts may cause explosion. To remove "scale", use very dilute hydrochloric acid and acetic acid to scrub, then pour out the acid immediately and wash with clean water.

8. Is the emollient effect of glycerin absolute? As we all know, pearl cream contains glycerin. The function of glycerin is to absorb moisture in the air and keep the skin moist. So, can pure glycerin be applied directly to the skin to moisturize it? No, because if pure glycerin is applied directly to the skin, it will not only absorb moisture from the air, but also suck out the moisture from the skin tissue, which will make the skin drier or even burn. Therefore, when buying glycerin, you must first ask whether it is pure glycerin or hydrated glycerin. If it is pure glycerin, 20% of water must be added before it can be used to moisturize the skin.

9. Why does the fruit turn black after being peeled with an iron knife? Fruits contain more or less an organic compound, tannic acid. When tannic acid comes into contact with iron or other heavy metals, it will decompose.

2. Common sense of physics and chemistry in daily life

Long jumpers always run a certain distance before taking off. Why is this? Answer: Using inertia, after jumping, the body must maintain its original speed and move forward to increase the distance of the long jump. Therefore, athletes run a certain distance before taking off.

2. Saws, scissors, and axes need to be sharpened after using them for a period of time. Why? Answer: Saws, scissors, and axes should be sharpened after using them for a period of time to make their teeth or blades sharp and reduce the stress-bearing area. When used, the same force can be used to increase the pressure. 3. Place the plastic clothes hook tightly on a smooth wall and use it to hang clothes or school bags.

What does this mean? Answer: When the plastic coat hook is pressed against the wall, the air between the plastic suction cup and the wall is squeezed out, and the atmospheric pressure presses the plastic suction cup tightly against the wall. After hanging clothes or school bags, the friction between the plastic suction cup and the wall balances the gravity of the clothes or school bags, so the clothes or school bags can be hung.

4. Why does the clock run longer if the spring is tightened? Answer: The tighter the spring is, the greater its deformation will be, so it will have more elastic potential energy. The more elastic potential energy will be converted into kinetic energy, and it will be able to push the gears of the clock to do more work and make the clock run. longer.

5. When the pen absorbs water, if you press the spring leaf on the pen a few times, the ink will be sucked into the rubber tube. What is the reason? Answer: When the spring leaf is pressed, part of the air in the rubber is squeezed out. After letting go, the rubber tube returns to its original shape, causing the air pressure inside the tube to be lower than the atmospheric pressure outside the tube. The ink is forced into the water tube by the atmospheric pressure outside the tube.

6. Food cooked in a pressure cooker cooks faster than in an ordinary pot. Why? Answer: Because the boiling point of water is related to pressure. As the pressure increases, the boiling point rises. When cooking food, the air pressure in the pressure cooker is higher than that in an ordinary pot. Therefore, when the water boils, the temperature in the pressure cooker is higher than that in an ordinary pot. The temperature The higher it is, the faster the food will cook. 7. How would you feel if you rub a little alcohol on your skin? What does this mean? Answer: If you rub a little alcohol on your skin, you will feel cool. This is because when the alcohol evaporates, it absorbs heat from the body, lowering the temperature of the skin and making it feel cold.

8. Incandescent light bulbs will turn black after being used for a long time. Why? Answer: Because the tungsten filament is heated and sublimates, and then the tungsten gas condenses on the wall of the bulb, incandescent bulbs will turn black after being used for a long time. 9. In winter, when people feel their hands are cold, they can rub their hands to warm them up, or they can put their hands in their trouser pockets to warm them up. In each of these two ways, the hands get heat. of? Answer: Rubbing hands gets heat through work; hand *** trouser pockets are heated with body temperature, which is getting heat through heat transfer.

10. Use the knowledge of molecular kinetic theory to explain that evaporation can occur at any temperature. Answer: At any temperature, molecules are constantly moving irregularly. There are always some molecules in the liquid that are so fast that they can overcome the attraction of other molecules on the liquid surface and run out of the liquid to become gas molecules. The liquid becomes gas.

11. When drinking boiled water, if you feel the hot water scalding your mouth, you usually blow air towards the water surface. What is the reason? Answer: This is because the temperature will decrease when the liquid evaporates, which means that the evaporation of the liquid has a cooling effect. Blowing air onto the water surface can speed up the flow of air on the water surface. The faster the air flows on the surface of the liquid, the faster it will evaporate. This will speed up the temperature drop of the water and prevent the hot water from scalding your mouth.

12. In winter, after people come into the house from outside, they always like to breathe into their hands with their mouths, and at the same time they like to rub their hands against each other. Why is this? Answer: It’s very cold outside in winter, and people’s hands are always wet, and the temperature exhaled by the human body is close to the human body temperature. Breathing into the hands can cause the hands to absorb the heat of the breath exhaled from the mouth; the hands rub against each other, and the friction force does work, increasing the The internal energy of the hand can make the hand warm. 13. In the winter in the north, when a person wearing glasses walks from outdoors into a warm room, a layer of small water droplets will appear on the lenses. Why? Answer: In winter, eyeglass lenses are cold outdoors. After entering a warm room, the water vapor contained in the air in the room encounters the cold lenses and liquefies (condensates) into small water droplets, which adhere to the lenses.

14. Theoretical explanation of the kinetic theory of hand molecules: In places where coal has been piled for a long time, there is a thick layer of soil that is black. Answer: Because coal is black, coal molecules are constantly moving irregularly, and the blackening of the soil is due to the diffusion of coal molecules; 15. When installing lighting circuits, if the fuse is not tightened tightly, Often easy to fuse.

Why? Answer: If the fuse is not tightened tightly, the contact resistance between the fuse and the terminal will increase. When the power is turned on, the ice in the contact part of the fuse and the terminal will heat up, and it will easily melt after a long time. 16. When electricians repair circuits, they use tools with wooden handles or rubber covers on the handles, and they often stand on a dry wooden bench. Why? Answer: Wooden handles, rubber covers and dry wooden benches are all insulators, which can prevent the current in the circuit from flowing into the earth through the human body, which can prevent electricians from getting electric shock.

17. The electric stove wire is so hot that it turns red, but the copper wire connected to the electric stove wire is not very hot. Why? Answer: Because the copper wire and the electric furnace wire are connected in series, according to Q=I2Rt, the current passing through is equal, but the resistance of the copper wire is much smaller than that of the electric furnace wire, so the electric furnace wire is hot and red, but the copper wire is not very hot. .

18. Under what circumstances does the fuse work? What does it protect? Answer: The fuse is connected in series in the circuit. When the current exceeds a certain value, the fuse will automatically blow and cut off the power supply, thus protecting the electrical appliances and circuits.

19. The picture on the right is the schematic diagram of an alarm alarm. K is the touch switch, and B is a funnel-shaped bamboo cylinder with a float A inside. Try to explain its working principle. Answer: When the water level rises and exceeds the warning line, float A rises, turning on the control circuit, and the electromagnet draws down the armature, so the alarm indicator circuit is turned on, and the light turns on to alarm.

3. Application of common sense of physical chemistry in life

This essay does not have 2000 words. You can add some points yourself. Copy below some things that can give you inspiration. When it comes to chemistry, Many people immediately think: Chemistry courses offered in middle school or college classrooms or that "chemistry" is a matter for chemists and scientists and has nothing to do with me.

However, chemistry is everywhere in our lives. For example, steel rusts, objects burn, proteins poison people, acid rain, etc. are all chemical phenomena.

So, what is chemistry? In layman's terms, it is the phenomenon in which one substance combines with another substance to synthesize another substance with new properties. For example, steel rusting is a chemical phenomenon.

As we all know, ordinary ironware will become rusty within one or two months if placed in a humid and ventilated place. You can go to the museum and see that none of the ironware on display is rusty.

The reason why iron rusts is because it contains impurity carbon, and carbon reacts with oxygen in the air under normal temperature conditions. Under the action of water (water vapor in the air), oxygen (symbol O) in the air breaks into the interior of the iron and combines with iron (Fe) to form another substance - ferric oxide (Fe3 O4).

Water is the main culprit that causes iron to rust. Chemists have proven that iron will not rust if placed in water-free air for several years.

If a piece of iron is placed in a boiled, completely closed distilled water bottle (no air in the bottle), it will not rust. Iron will rust only when oxygen and water attack iron at the same time.

In addition, carbon dioxide (CO2) in the air will also cause iron to rust when it encounters iron. Rust is loose and soft, and like a sponge, it will continuously absorb water, causing the rusted area of ????the iron to continue to increase.

The rate of corrosion is accelerating. I have done experiments. After a piece of iron is completely rusted, its volume is several times larger than its original size.

Some metals also rust (i.e. "oxidize"). For example, after being used for a long time, the surface gloss of an aluminum pot will gradually disappear and be covered by a layer of "aluminum rust". This "aluminum rust" is aluminum oxide - it is formed after a chemical reaction between aluminum and oxygen in the air. formed.

In order to reduce iron rust, smelters smelt the initially refined ordinary iron through high-temperature oxygenation smelting to further remove the carbon contained in the pig iron. The performance of the iron smelted in this way and its anti-oxidation reaction are improved compared to the original.

At this time, iron becomes "steel". People have come up with all sorts of ways to protect steel.

The most common method is to "dress" the iron - coating the surface with paint or plating other metals that are not prone to rust. For example, the car is dressed in shiny spray paint, the heating pipe is coated with aluminum paint, the tinplate used for cans is plated with a layer of tin, the surface of the tin plate is plated with a layer of zinc, and so on.

Its purpose is to insulate steel from water and air so that it cannot undergo chemical reactions. As we all know, burning objects requires fire.

So, how did the case above and those large-scale forest fires occur without fire? It turns out that whether an object burns, in addition to air (oxygen), it also needs a temperature limit, called the "ignition point". That is, when a certain temperature is reached, the object will burn without fire.

Dry paper and trees have very low ignition points and can easily spontaneously ignite without fire at high temperatures. This is how the above cases and forest fires occurred.

The burning of objects seems to have nothing to do with chemistry, but in fact it is very closely related.

Combustion is a violent chemical reaction phenomenon: a substance oxidizes with air (oxygen) at high temperature to produce another substance (such as carbon dioxide). During the oxidation reaction, huge amounts of energy—heat energy—are released, which is what we see as fire.

The carbon contained in paper, wood, and leaves reacts with oxygen in the air at high temperatures to form a gaseous substance called carbon dioxide (symbol CO2) that floats into the air and disappears. Therefore, after burning gasoline, there is no paper, clothing, and only a few and light ash is left after burning wood.

These ash are other impurities contained in the object that cannot react with oxygen. Coal, gasoline, clothing, and other objects burn similarly.

After understanding the principle of combustion, people have come up with various ways to prevent and extinguish fires. For example, use high-temperature resistant fireproof materials to build houses, use foam fire extinguishers to put out fires when making furniture, etc.

If the oil pan burns because the temperature is too high while you are cooking, don’t panic. Just cover the pan immediately and the fire in the oil pan will be extinguished. If a fire breaks out in an electrical appliance due to aging or short circuit, don’t be afraid. Cover the burning electrical appliance with a thick quilt immediately to extinguish the fire.

Please think about the reason for this (water will make the fire more intense if the oil pan is on fire and water will hurt people if the appliance is on fire). The spontaneous combustion of matches used by people without fire during friction is also a chemical reaction phenomenon.

There are sulfur particles, gunpowder and other substances in the match head. "Rubbing" is made of rough paper coated with a layer of phosphorus.

Sulfur, gunpowder, phosphorus, etc. are all flammable substances with very low ignition points. When making a fire, just rub the match head hard on the phosphorus paper. At this time, the friction between phosphorus and sulfur will generate high temperature, and the stick will ignite.

But the previous matchsticks could be rubbed on the wall and were unsafe. The match of the little girl in the famous fairy tale "The Little Match Girl" is this kind of match.

1. Why do shrimp crackers swell when fried in oil? Shrimp crackers are made with cooked starch. During production, some air is enclosed in the many micropores formed inside.

Because these micropores are so small, we cannot see them with the naked eye. Put the shrimp slices into the hot oil pan. On the one hand, the cooked starch will soften when heated, and on the other hand, the air in the micropores will expand rapidly when heated.

The air inside will be squeezed out, and the cooked starch outside will soften again, so the shrimp crackers will expand immediately. When the temperature drops and the starch on the outside hardens, the shrimp chips become soft, crispy and chubby.

2. Why are women usually more likely to float on their backs than men? In the summer, we went swimming together. Several male classmates tried to float on the water without moving. They found that their feet always sank down. But the female classmates next to them could float on their backs on the water.

Why is this? We know that the average density of humans varies around 1.0*l03kg/m3. When a person holds his breath, the density of humans is less than that of water, and humans should be able to float on the water; but the density of men is greater than that of women. This is because the proportion of body fat in women is higher than that in men. Women's body fat accounts for about 20% of their body weight.

4. Common sense about physics and chemistry in life

1. Two chemical humors (1) Husband: Send me to the hospital quickly, I just choked on gasoline! Wife: (slowly) Cough, it’s okay, as long as you don’t smoke these days.

(2) Long-distance passenger bus station. A man hurried over with a large bucket of something. As he was squeezing to get on the bus, the conductor asked: "Hey, what is this?" The man sulked and said, "Alcohol" while squeezing up.

"No, no, this is flammable and cannot be brought on board," the ticket seller frowned. The man shouted again: "This is ethanol."

"Why didn't you tell me earlier? Haha, hurry up!" the conductor complained to the man with a smile. The bus finally started... 2. Ethanol contains injustice "Bring the defendant with you!" Uncle Tie sat on the judge's bench with a dignified manner, staring at me coldly.

"Who is the defendant?" "Little...the little one is called ethanol, and everyone calls me alcohol. I was born in a fermentation tank, born of corn and sorghum.

Now working in cars, providing energy for cars. ""You are charged with intentional injury and murder.

According to relevant witnesses, you got into the "***" at 9 o'clock yesterday. In the wine bottle, he did evil things in the human body, causing five people to lose their sight and two people to die..." The elder brother of the judge said plausibly. "It's unfair. Yesterday, I worked with Gasoline on the car.

The younger one is a good citizen and a friend of mankind. I wonder if the witness saw my brother as me.

Next, let me introduce myself. My body is composed of 6 hydrogen atoms, 2 carbon atoms, and 1 oxygen atom.

Once I see oxygen, I will. I will dance with it in the fire, release all my enthusiasm, and my body will magically become two parts.

One is the CO2 that joins the air family; the other is the source of life-water. . For my outstanding contribution, I was also awarded the Green Energy Award.

This also gave me a new job. I am a good citizen and never do anything wrong.

Outside of work, I also play a game of disguise with my good friend Sodium. We take apart various parts of our bodies and then enter each other's bodies according to the rules we agreed on, thus becoming sodium acetate and hydrogen. At the time of the crime, I was playing a game of disguise. How could I commit the crime? "Yes, I can prove that I was with him at the time of the crime."

Seeing friends in times of trouble, Na. My little brother is worthy of being my life and death friend. At this moment, a man broke into the door.

The audience was in an uproar, because it is my brother-methanol! "I surrender!" he said expressionlessly. "I...I am the criminal who caused blindness and death."

The trial is over. I am free again.

Long live freedom. 3. Metal fights for the throne The residents of the Metal Kingdom have been living a peaceful life.

It is said to be a "kingdom", but the metal kingdom has never had a king. So one day, the oldest metal copper in the kingdom called everyone together and said: "I don't think this can continue. Other kingdoms have kings. How can we still live a primitive life like us? Now, let's come Choose a king!" After hearing this, all the metals immediately started talking, wondering who should be chosen as the king.

While everyone was hesitating, the shining gold jumped out and shouted: "Is there still a choice? Of course I will be the king! No one knows my reputation, no one knows it Everyone knows that I am the most valuable metal, because I have the least content in the earth’s crust. What’s more, people are willing to use me as decorations to beautify their lives. How about giving medals made by me to those who win the big competitions! "Well, what's so great about having a high status?" The shining silver man stood up and said with dissatisfaction. , "To say that the best candidate for the king is me, Lao Tie. First of all, my qualifications are also very old, only a few years later than Tong Laosheng; secondly, my uses are very wide, which is wider than any metal, so I am also the metal with the highest annual output in the world.

Even the human body cannot lack me! It seems that I will be the king! "" Wait a minute!" The young metal aluminum said indifferently to the elders. Without being polite, "You two, step aside. One of you says you are worth a lot, and the other says you have a large output. I don't think you are qualified! Look at me, I am the person with the third highest element content and the highest metal content in the earth's crust. The number of years of mining is also at the top of the list, far exceeding that of your uncle Iron. Besides, people have used me much later than copper and iron, but my density is small and I have excellent properties such as corrosion resistance. The annual output has exceeded that of copper, ranking second only to iron.

People can say that they care more about me now, but they don’t care about copper and iron as much as before, and they even have more. A derogatory term like "broken copper and scrap iron".

So, it’s not an exaggeration for me to be a king! ""presumptuous! Tong, the eldest man, stood aside with anger and his beard stood up, "You actually insulted me, your elder, in public. If you want to be the king, it would be better for me."

First of all, I am older than you. People have been using bronze as early as the Shang Dynasty; then, because of its good electrical conductivity and low cost, it has been widely used in human power projects; in addition, it has good electrical conductivity and is not expensive. I also have many uses, such as making coins, making decorations, etc. Even if you are dissatisfied, you must respect me as an elder and my contribution to mankind! "After listening to their heated debate about the four metals, everyone started talking and getting excited, and the election scene suddenly became tense.

"Then I am the metal element with the highest content in the human body! "Calcium was the first to shout. "My worth is not low, and I have the best electrical and thermal conductivity. Why can't I be the king? "Yin also couldn't sit still.

"I have the highest hardness, and I am also qualified to run. "Chrome couldn't help shouting.

"I'm different. I'm usually in a liquid state. This is because I have the lowest melting point. Should I be chosen? "Hurry, who is usually gentle, became anxious today. "And I..." Various metals have come up with their own special skills, trying to overwhelm other metals. Everyone has become the king, and no one will give in.

So, the "planner" Tong quickly announced: "Stop, stop, let's get here today, and we will talk about electing the king another day..." I don't know if they can finally elect the king. This is really a headache for them. A big problem! 4. Fe Wandering Adventures was used as early as the Spring and Autumn Period and the Warring States Period. It turns out that I am a gray-white mineral that grows in the deep mountains and old forests.

I condense.