2. The metal used to make metal foil (metal paper) for packaging cigarettes and sweets is aluminum.
The melting point of gold is 1064.4℃, and there are many metals with higher melting point than it. This is about three times higher than the melting point of gold.
The metal commonly used to make incandescent filament is tungsten.
4. A woman made a pair of goldsmith's earrings from an old gold ring of 6. 10g. She was afraid that the craftsman would steal it.
Gold or adulteration, always stay by. She saw the craftsman heat and beat the ring, releasing a liquid.
After many times of processing, a pair of beautiful earrings were processed. After a few days, balance the earrings.
Weighing, only 5.20 grams. Then the liquid used by craftsmen to steal gold is aqua regia.
5. The black substance in black-and-white photos is: silver.
6. Many chemical elements play an important role in people's life. Without them, people will get sick.
For example, children often suffer from rickets because of a lack of: calcium.
7. A lamp made by filling a quartz tube with a certain gas emits hundreds of millions of times more light than a fluorescent lamp.
Light, so it is called "artificial little sun". The gas in this lamp is xenon.
8. Making a fire to keep warm in a room with closed doors and windows or taking a bath with a water heater often produces a colorless and tasteless taste.
The gas that is easy to combine with human hemoglobin (Hb) and cause poisoning is: CO.
9. The destruction of the earth's atmosphere will form an ozone hole, which will make people resist the ultraviolet rays of the sun.
The destroyed ozone layer is destroyed, which causes diseases such as skin cancer and destroys the ecological balance of nature.
. The main cause of the ozone hole is the leakage of freon in the refrigerator.
10. The concentration of medical disinfection alcohol is 75%.
1 1. Normal saline commonly used in hospital infusion contains sodium chloride, which is roughly the same as that in blood.
Wait a minute. The mass fraction of NaCl in physiological saline is 0.9%.
12. After the "gunpowder paper" (spark) in the starting gun is fired, the white smoke produced is phosphorus pentoxide.
13. Naphthalene sanitary balls will become smaller when put in the closet, because naphthalene sublimates slowly at room temperature.
14. People's skin is itchy or red and swollen after being bitten by mosquitoes. The simple treatment method is to rub dilute ammonia or bicarbonate.
Sodium solution.
15. Because a certain gas A is excessively accumulated in the atmosphere, the infrared radiation of the earth cannot penetrate the atmosphere, so
The gas A that causes the atmospheric temperature to rise and produces the "greenhouse effect" is carbon dioxide.
16. Acid rain refers to rain, snow or other forms of atmospheric precipitation with a pH value less than 5.6. Acid rain is air pollution.
A manifestation of dyeing. The main causes of acid rain are: secondary emissions from fuel combustion.
Sulfur oxide, nitrogen dioxide, etc.
17. The iron wire bought at the hardware store was coated with a layer of "anti-corrosion" metal, namely zinc.
18. All-steel watch means that its case and back cover are all stainless steel. Stainless steel is shiny, isn't it?
It rusted because chromium and nickel were added in the steelmaking process.
19. Photocells are made according to the nature that ordinary light irradiates metals to release electrons, and are widely used in movies.
In cameras and video recorders. The metal used to make photovoltaic cells is cesium.
20. "Barium meal" radiography is often used in hospital radiology to check diseases in esophagus, stomach and other parts. Used as "barium"
The substance of this meal is: barium sulfate.
2 1. Mr. Hou is a world-famous expert in alkali production in China. He invented Hou's alkali production method in 1942. prepare
Alkali is not only used in industry, but also added to fried dough sticks and steamed bread in daily life. This alkalinity
The chemical name is sodium carbonate.
22. The door and window frames of modern buildings are made of hard aluminum plated with bronze.
Composition: Al-Cu-Mg-Mn-Si alloy.
23. Barium chloride is highly toxic, with a lethal dose of 0.8g When taken by mistake, in addition to swallowing a large amount of egg white to detoxify,
And take a certain amount of antidote. This antidote is magnesium sulfate.
Printed circuit boards are usually produced by chemical etching. This chemical etchant is: ferric chloride.
25. Liquefied petroleum gas has already entered the family. Its main components are propane and butane.
26. The main component of natural gas is methane. If there is a set of stoves that use natural gas as fuel and burn liquefied petroleum gas instead.
The correct measures to be taken are: increasing the air intake or reducing the air intake of liquefied gas.
27. After the gas tank filled with liquefied gas is used up, you will often hear the sound of shaking when shaking, but this kind of water sound
Do not dump liquid without permission. The main reason is that this liquid is a hydrocarbon with a little more carbon, just like gasoline.
Flammable, prone to fire and other accidents.
28. Recording tapes are made of acetate fibers, polyester fibers and other fibers, and are uniformly coated with a layer of magnetism.
Material-made of magnetic powder. The main material for preparing magnetic powder is ferroferric oxide.
29. When masons paint walls with slaked lime, they often add a small amount of coarse salt to the lime, which is the purpose of coarse salt.
The deliquescent substances contained in it deliquesce, which is beneficial to the absorption of carbon dioxide. This easy-to-relieve substance is chlorine.
Magnesium oxide.
30. The reason why the original works of ancient calligraphers in China can be preserved so far is to use ink or carbon ink to make handwriting.
Do not fade for a long time, because the chemical properties of carbon are stable.
3 1. The author's seal is often left on paintings and calligraphy, which is bright and ruddy because the red inkpad contains indelible ink.
The chemically stable red substance should be cinnabar (mercury sulfide).
32. With the improvement of people's living standards, gold jewelry has become a favorite ornament. Made of gold
The unit of purity is K, and 24K usually represents pure gold or red gold, and the actual gold content is above 99%. Gold nib, gold
The watchcases are all 14K, and their usual gold content is: not less than 56%.
Smoking can cause bronchitis and cardiovascular diseases, as well as lung cancer, oral cancer, gastric cancer and bladder cancer.
Waiting for cancer, so smoking is a chronic suicide. The World Health Assembly designated April 7th every year as "World Quit Smoking Day".
"。 According to analysis, the most harmful substances in tobacco components are nicotine and benzo (a) pyrene.
34. The submarine has been sailing in deep water for a long time, and the best substance to provide oxygen for the crew to breathe is excess oxygen.
Sodium oxide.
35. The glass sheet of color-changing glasses will darken in the sun because the right amount of people are added to the glass.
Silver halide crystals and copper oxide.
36. Lead poisoning can lead to anemia, headache, memory loss and digestive system diseases. Acute poisoning can cause slowness.
Sexual brain injury is often life-threatening. The main source of lead pollution in urban air is automobile exhaust.
37. The cooling water in the water tanks of automobiles and diesel engines will burst when it freezes in winter. To prevent
When freezing, a small amount of ethylene glycol is often added.
38. The gray manganese oxide or PP powder in the hospital is potassium permanganate.
39. The preservative in high orange drinks and cans is sodium benzoate.
40. The main components of scale in kettles, thermos bottles and boilers are calcium carbonate and magnesium hydroxide.
4 1. The substance that can't be used to make wine is: soybean. The substances that can be used to make wine are: millet, corn, sorghum and red.
Potatoes and so on.
42. After strenuous exercise, I feel sore all over. This is because lactic acid in my muscles has increased.
43. Among nutrients, the one with high calorific value and the longest stay in the gastrointestinal tract after eating (satiety) is: fat.
Fat.
44. monosodium glutamate, also known as monosodium glutamate, has a strong meat flavor and its chemical name is 2- aminosuccinic acid.
Sodium (monosodium glutamate).
45. After the first frost, vegetables and radishes taste sweet, because the starch in vegetables is planted.
Glucose is produced by hydrolysis under the action of enzymes in substances.
46. Why did the ancients "fish for three days and dry the net for two days"? Because fishing nets used to be made of hemp fiber,
Hemp fiber is easy to swell when it absorbs water, and it is easy to rot when it is wet, so the fishing net will be hung for two days after two or three days to prolong the fishing net.
Life expectancy. There is no need to do this now, because the materials used to weave fishing nets are generally nylon fibers.
47. When theatrical performances are shown on TV, we often see smoke on the stage, which is now widely used as a smoking agent.
Yes: ethylene glycol and dry ice.
48. To raise goldfish with tap water, you need to bask in the sun for a while, and then fill the fish tank with water. The purpose is:
Decomposition of hypochlorous acid in water.
49. If the edible oil is stored for a long time, the best container is a glass or ceramic container.
50. The non-stick pan does not stick to food because the bottom of the pan is coated with a special substance: "Teflon".
Its chemical name is PTFE, commonly known as plastic king.