isotope
Isotopes existing in nature are: H 1 (Pi), H2 (deuterium dāo, heavy hydrogen), H3 (tritium chuān, overweight hydrogen). Isotopes synthesized by artificial methods are: hydrogen 4, hydrogen 5, hydrogen 6 and hydrogen 7.
Alias, English name
Deuterium; Deuterium, heavy hydrogen.
Toxicity and safety protection
Heavy hydrogen is non-toxic and suffocating. Heavy hydrogen is flammable and explosive, so we should pay enough attention to it. Others see hydrogen.
[Edit this paragraph] Found that
1766 was discovered by H. cavendish in England. In the history of chemistry, the discovery of hydrogen and the discovery and proof that water is a hydroxide compound rather than an element are mainly attributed to the British chemist and physicist cavendish (H.1731-1810).
/kloc-cavendish, an English chemist in the 0/8th century.
Cavendish is a millionaire, but his life is very simple. He built a large-scale laboratory at home with his own money and devoted his life to scientific research. A historian of science once said: cavendish "is the richest among the learned and the most learned among the rich." He has a keen observation of things and is good at experimental design. His experimental results are quite accurate, and his research scope is very wide. He made important discoveries in many chemical, mechanical and electrical problems and in the study of the average density of the earth. But he believed in phlogiston, which made him take some detours in chemical research. In the past 50 years, he has only published 18 papers, all of which are experimental and observational except one which is theoretical. After his death, it was found that he wrote a lot of valuable papers, but they were not published. These manuscripts of his are precious documents of scientific research, which were later compiled and published by physicist Maxwell and chemist Thorpe respectively. There is an interesting story about these papers in the history of chemistry. Cavendish did an experiment in 1785. He let an electric spark pass through the mixture of ordinary air and oxygen, trying to oxidize all the nitrogen in it, and the nitrogen dioxide produced was absorbed by caustic potash. The experiment was done for three weeks, and finally there was a small bubble that could not be oxidized. His experimental records are kept in the manuscript, which reads: "The polluted air in the air is not a single substance (nitrogen), and there is another polluted air that is not combined with defluorinated air (oxygen), and the total amount does not exceed112. More than one hundred years later, 65,438+0,892, a physicist at Cambridge University, England. L.1842-1919), it is puzzling that the nitrogen obtained from the air is 0.0064 g per liter heavier than the nitrogen produced by ammoxidation. Chemist Ramsay (W.1852-1916) thinks that nitrogen in the air can contain heavier unknown gases. At this time, the chemistry professor Dewar (J. 1842- 1923) mentioned to them the above experiment of Cavendish, a doyen of Cambridge University, and the mystery of small bubbles. They immediately borrowed Cavendish's scientific data to read, and Rayleigh repeated Cavendish's experiment that year, and soon got a small bubble. Ramsar designed a new experiment. After removing water vapor, carbonic acid gas, oxygen and nitrogen from the air, this gas is also obtained, and its density is higher than that of nitrogen. It is proved by spectroscopic examination that it is a new element named argon. In this way, Cavendish's work in that year played an important role in the discovery of argon in 1894. From this story, we can see Cavendish's rigorous scientific research style and his great contribution to chemistry. 187 1 year, Cambridge university established a physics laboratory named after Cavendish. This is the famous Cavendish laboratory, which has been an important research center of modern physics in the world for decades.
The discovery of hydrogen and its properties.
Before the end of 18, many people had done experiments to make hydrogen, so it is hard to say who discovered hydrogen. Even cavendish, who has made great contributions to the discovery and research of hydrogen, thinks that the discovery of hydrogen is not only his credit. As early as16th century, the famous Swiss doctor's palace described that iron filings would produce a gas when they came into contact with acid. /kloc-in the 0/7th century, Helmont (J.B. 1579- 1644), a famous Belgian medical chemist, accidentally came into contact with this gas, but failed to separate and collect it. Although Boyle collected this gas by accident, he didn't study it. They only know that it is flammable and know little about it. 1700, French pharmacist Lhemery (n.1645-1715) was also mentioned in the report of the Paris Academy of Sciences. It was cavendish who first collected hydrogen and studied its properties carefully. 1766, cavendish submitted a research report "Artificial Air Experiment" to the Royal Society, which described that he made "combustible air" (i.e. hydrogen) by reacting iron and zinc with dilute sulfuric acid and dilute hydrochloric acid, and collected it for research by the drainage gas collection method invented by priestley. He found that a certain amount of a metal reacts with a sufficient amount of various acids, and the amount of this gas produced is fixed, regardless of the type and concentration of the acid. He also found that when hydrogen is mixed with air and ignited, it will explode; It is also found that hydrogen combines with oxygen to form water, thus realizing that this gas is different from other known gases. However, because he is a devout believer in phlogiston theory, according to his understanding: this gas burns so violently that it is bound to be rich in phlogiston; Sulfur turns into sulfuric acid after combustion, so there is no phlogiston in sulfuric acid; According to phlogiston, metals also contain phlogiston. So he thinks that this gas is decomposed by metal, not by acid. He imagined that when metal was dissolved in acid, "the phlogiston contained in it was released, and this combustible air was formed". He even assumed that hydrogen was phlogiston at one time, which was quickly endorsed by some outstanding chemists at that time, such as Scheler and Kilwan (Kirwan, R.1735-1812). Because the bladder balloon is filled with hydrogen, the balloon will rise slowly. This phenomenon is used by some believers of phlogiston theory as the basis of their "argument" that phlogiston has negative weight. But cavendish is an extraordinary scientist after all. Later, he calculated the buoyancy of the balloon in the air. Through accurate research, it is proved that hydrogen has weight, but it is much lighter than air. The experiment he did was as follows: first weigh the metal and the flask containing acid, then put the metal into the acid, collect hydrogen through drainage and gas collection and measure it, and then weigh the total amount of the flask and its contents after the reaction. In this way, he determined that the proportion of hydrogen is only 9% of that of air. But these chemists still refuse to give up the old theory easily. In view of the fact that hydrogen will produce water after burning, they say that hydrogen is a compound of phlogiston and water. The synthesis of water denies the wrong view that water is an element. In ancient Greece, empedocles proposed that there were only four elements in the universe, namely, fire, air, water and earth, which constituted everything. From then until the 1970s, people always thought that water was an element. 178 1 year, priestley put hydrogen and air into a closed glass bottle and detonated it with an electric spark. Dewdrops appeared on the inner wall of the bottle. In the same year, cavendish also repeated the experiment with a mixture of hydrogen and air in different proportions, confirming that the dew is pure water, indicating that hydrogen is a component of water. At this time, oxygen has been discovered. cavendish used pure oxygen instead of air to carry out experiments, which not only proved that hydrogen and oxidation synthesized water, but also confirmed that about 2 parts by volume of hydrogen and 1 part by volume of oxygen just synthesized water (published in 1784). These experimental results undoubtedly prove that water is a compound of hydrogen and oxygen, not an element, but cavendish, like priestley, still insists that water is an element, oxygen is water without phlogiston, and hydrogen is water with excessive phlogiston. He expressed the combustion of "combustible air" (hydrogen) with the following formula: (water+phlogiston)+(water-phlogiston) → water combustible air (hydrogen) phlogiston loses air (oxygen) 1782. lavoisier repeated their experiments, decomposed water vapor with a red-hot barrel, and clearly put forward the correct conclusion: water is not an element, but hydrogen. 1787, he named this gas "h-hydrogene", which means "producing water", and confirmed that it was an element.
[Edit this paragraph] Physical and chemical properties
Hydrogen is a colorless gas, and its density is lower than that of air. Under standard conditions, the mass of 1 liter hydrogen is 0.0899g, which is much lighter than air). Because hydrogen is insoluble in water, it can be collected by drainage and gas collection. In addition, at the pressure of 10 1 kPa and the temperature of -252.87℃, hydrogen can be converted into a colorless liquid. At -259. 1℃, it becomes a snow-like solid. At room temperature, the nature of hydrogen is very stable and it is not easy to react with other substances. But when the conditions change (such as ignition, heating, using catalyst, etc. ), the situation is different. For example, after hydrogen is adsorbed by metals such as palladium or platinum, it has strong activity (especially palladium adsorption). Palladium metal has the strongest adsorption effect on hydrogen. Summarized as: molecular formula: H2 boiling point: -252.77℃(20.38K) density: 0.09kg/m3 relative molecular weight: 2.0 16 production method: electrolysis, pyrolysis, coal gasification and other molecular weights: 4.032 triple point: -254.4℃ liquid density (equilibrium state, -252.8℃): 169 kg/m3 gas density (101.325kpa438+0.02961.02961.06001. Kg gasification heat △ HV (-249.5℃): 305kJ/kg specific heat (10 1.335kPa, 25℃, gas): CP = 7.243kJ/(kg k) cv = 5.170. 17.703): 10.67 kPa normal state,/10 1.325kPa, 0℃): 0℃): 0.010 lmpa s (liquid, equilibrium state,-. 0℃): 0.1289w/(m k) (liquid,-252.8℃):'1264w/(m k) Refractive coefficient nv( 10 1.325kPa). 25℃): 1.000 1265 Combustion limit in air: 5% ~ 75% (by volume) Flammability grade: 4 Toxicity grade: 0 Explosive grade: 1 it contains 0.0139% ~ 0.0 in water. Its chemical properties are exactly the same as ordinary hydrogen. However, due to the large mass, the reaction speed is small.
[edit this paragraph] hydrogen classification standard
Industrial hydrogen GB/T3634- 1995 H2≥99.90% (excellent product) H2≥99.50% (first-class product) H2≥99.00% (qualified product) Pure hydrogen GB/T7445- 1995 H2≥99.99%. T7445- 1995 H2≥99.999% ultra-high purity hydrogen GB/t7445-1995h2 ≥ 99.9999% hydrogen is hydrogen and oxygen generated by water electrification.
[Edit this paragraph] Main performance
High flammability, reducing agent, liquid temperature is lower than nitrogen.
A. Flammability:
The ignition temperature of pure hydrogen is 400℃. When hydrogen burns in the air, it actually reacts with oxygen in the air to produce water. During the reaction of 2H2+O2=2H2O (ignition), a lot of heat is released and the flame is light blue. The heat released during combustion is three times that of gasoline under the same conditions. Therefore, it can be used as high-energy fuel for rockets. China's Long March 3 rocket uses liquid hydrogen fuel. When impure H2 is ignited, it will explode. However, there are limits. When the volume of hydrogen contained in the air accounts for 4%-74.2% of the mixed volume, it will explode when ignited. This volume fraction range is called the explosion limit. Collect a tube of hydrogen with a test tube, and then put a burning wood on the mouth of the test tube. If you hear a slight "poof", it means that hydrogen is pure. If you hear a sharp crack, it means that the hydrogen is impure. At this time, it is necessary to collect and test again. If the exhaust method is used for collection, it is necessary to block the mouth of the test tube for a while with your thumb so that the flame in the test tube will not go out, and then hydrogen can be collected (or another test tube can be taken for collection). After collection, block the mouth of the test tube with your thumb, move it closer to the flame and then move it away to see if there is a "poof" until the test shows that the hydrogen is pure. When hydrogen burns in the air, it will emit a light blue flame, and its device will be ignited directly in the glass tip tube. So can we really see the light blue flame? There are sodium ions in the glass, but the flame color of sodium ions is yellow, so only the yellow flame can be seen by the above method, but the light blue flame can not be seen. If you want to achieve a light blue flame, you can adopt the following methods: method 1: use a timely catheter (expensive, not suitable for ordinary middle school laboratories); Method 2: use copper tube (deceptive, because the flame color of copper is green, copper can conduct heat, and the connection between copper tube and rubber tube will affect the air tightness); Method 3: Because the yellow flame is caused by sodium ions in the glass, we can use the flame reaction to test potassium through cobalt glass.
B. Reducing capacity
The reaction between hydrogen and copper oxide is essentially that hydrogen takes oxygen away from copper oxide to generate water, which turns copper oxide into red metallic copper. CuO+H2=Cu+H2O (heating) CO+3H2=CH4+H2O (catalyst) In this reaction, copper oxide loses oxygen and becomes copper, that is, copper oxide is reduced. This reaction of oxygen-containing compounds losing oxygen is called reduction reaction. A substance that can obtain oxygen from an oxide and make it undergo a reduction reaction is called a reducing agent. The reducing agent is reducible. According to the combustion characteristics of hydrogen, it can be used as fuel and applied to aerospace, welding, military and other aspects. According to its reducibility, it can also be used to smelt some metal materials. In addition, the addition reaction between hydrogen and organic matter also reflects the reducibility of hydrogen, for example, CH2 = CH2+H2→ CH3CH3 1) The test tube mouth of the reduction device should be slightly inclined downward; The conduit for introducing hydrogen should extend to the bottom of the test tube; The mouth of the test tube cannot be plugged with a rubber plug; 4) use alcohol lamp to heat; 2) pure hydrogen should be introduced for a period of time before the experiment, and then heating should be started; 2) After the experiment, the alcohol lamp should be removed to continue. The abbreviation is "first two, then two, first turn on the hydrogen, then turn on the light, first turn on the light and then stop the hydrogen."
[Edit this paragraph] Production method of hydrogen
A method for producing crude hydrogen:
Primitive hydrogen is hydrogen formed by primary particles in BIGBANG, which is mostly distributed in space and big planets. It is the nuclear fuel of stars and the initial substance of various elements and substances in the universe. There is no primitive hydrogen on the earth because gravity can't bind it. Only its compounds.
Production method of artificial hydrogen:
It can be divided into the following methods: (1) hydrogen production from coal and water (production equipment, gas-making equipment and pressure swing adsorption equipment) (2) production of cracked petroleum gas (production equipment, cracking equipment, pressure swing adsorption equipment and decarbonization equipment) (3) production of electrolytic water (production equipment and electrolytic cell equipment) (4) industrial waste gas. Civil hydrogen production method: ① ammonia decomposition (production equipment: gasifier, calciner, pressure swing adsorption equipment) ② active metal and acid (production equipment: stainless steel or glass container equipment) ② strong alkali and aluminum or silicon (production equipment: hydrogen balloon filling machine equipment) This method is generally used to produce hydrogen balloons. 3. Laboratory hydrogen production method: sulfuric acid and zinc particles (production equipment: Kipp generator) 4. Others (1) are electrolyzed with heavy water. (2) Liquid hydrogen is used for low-temperature refining.
[Edit this paragraph] Hydrogen production method
Laboratory preparation of hydrogen ⅰ. Laboratory preparation method
1. Reacts with strong acid and active metal, such as Zn+H2SO4 = ZnSO4+H2 = 2. React with alkali metal and water, such as 2Na+2H2O = 2NaOH+H2 =
Second, industrial law.
1. Electrolyze saturated brine to produce hydrogen, such as 2NaCl+2H2O = 2NaOH+Cl2 = 2. Industrial water will react with hot carbon. 3. It is made by the reaction of aluminum and sodium hydroxide: 2Al+2NaOH+2H2O = 2NALO2+3H2 =
Third, a new method of producing hydrogen.
The method of placing the gas container filled with hydrogen is 1. Cuprous oxide catalyzes hydrogen production from water. 2. Hydrogen production from water with a new molybdenum compound. 3. The method of completely decomposing water by photocatalyst reaction and ultrasonic irradiation. 4. Ceramics react with water to produce hydrogen. 5. Rapid pyrolysis of biomass oil to produce hydrogen. 6. Enzymes extracted from microorganisms produce hydrogen. 7. Use bacteria to produce hydrogen. 8. Using green algae to produce hydrogen. 9. Biological hydrogen production by organic wastewater fermentation. 10. Using solar energy to produce hydrogen from biomass and water. Using solar energy to produce hydrogen from biomass and water is the best way to produce hydrogen. The reason is that solar energy is huge, inexhaustible, clean and pollution-free, and does not need to be mined and transported. The cost of how to make hydrogen is greatly reduced. 1 1. With titanium dioxide as catalyst, water is decomposed into hydrogen and oxygen under laser irradiation.
[Edit this paragraph] Flammability of hydrogen.
Light the pure hydrogen at the mouth of the catheter with a sharp nozzle and observe the color of the flame. Then cover the flame with a cold and dry beaker. After a while, we can see pure hydrogen quietly burning in the air, producing a light blue flame (when hydrogen burns in a glass conduit, the flame is often yellowish). When the beaker is placed above the flame, water droplets will form on the wall of the beaker, and the hands touching the beaker will feel hot. Hydrogen burns in air. In fact, hydrogen reacts with oxygen in the air to produce water and give off a lot of heat. The chemical equation of this reaction is: 2h2+O2 = 2h2o (ignition). Take a paper tube (or plastic tube, etc. ) one end is open, the other end is drilled with a small hole, the small hole is plugged with a paper ball, and the paper tube is filled with hydrogen by exhausting downward to collect hydrogen. Remove the hydrogen generator, remove the paper ball that blocks the small hole, and light the small hole with the burning wood. Pay attention to what happens. When doing this experiment, people should stay away and pay attention to safety. ) We can see that when it was just ignited, hydrogen quietly burned. After a while, we suddenly heard a bang, and the exploding air billow blew the paper tube high. Experiments show that if the volume of hydrogen mixed in the air reaches 4% ~ 74.2% of the total volume, it will explode when it is ignited. This range is called the explosion limit of hydrogen. In fact, any combustible gas or combustible dust may explode in case of fire if it is fully mixed with air. Therefore, when combustible gases (such as hydrogen, liquefied petroleum gas, gas, etc. ) leakage, all fire sources and sparks should be eliminated, and electric sparks are prohibited to prevent explosion. It is for this reason that we should pay special attention to safety when using hydrogen. Be sure to check the purity of hydrogen before ignition. Collect a hydrogen test tube by drainage, plug it with your thumb, move closer to the flame, remove your thumb and light it. If you hear a sharp explosion, it means that hydrogen is impure and needs to be collected again and tested again until the noise is very low. There is only a bang, which means that hydrogen is pure. If the hydrogen is collected by downward deflation, if it is found to be impure, when it needs to be checked again, you should block the test tube mouth with your thumb for a while (to prevent the test tube producing hydrogen from being ignited) and then collect the hydrogen to check the purity, otherwise there will be the danger of explosion. Because the hydrogen flame may not go out in the test tube that has just been tested for purity, if hydrogen is collected in the test tube immediately, the hydrogen flame may ignite the hydrogen mixed with air in the hydrogen generator, leading to the explosion of the hydrogen generator. Plug the mouth of the test tube with your thumb for a while, so that the unburned hydrogen flame in the test tube is extinguished by oxygen-deficient gas. In addition, hydrogen can be ignited at low temperature with excessive oxygen and catalyst, and hydrogen peroxide (H2O2) can be generated (the valence of oxygen is 1).
[Edit this paragraph] Application
Hydrogen is not only the main industrial raw material, but also the most important industrial gas and special gas, which is widely used in petrochemical industry, electronic industry, metallurgical industry, food processing, float glass, fine organic synthesis, aerospace and other fields. At the same time, hydrogen is also an ideal secondary energy (secondary energy refers to energy that must be made from primary energy such as solar energy and coal). Generally speaking, hydrogen can easily combine with oxygen. This characteristic makes it a natural reducing agent to prevent oxidation in production. In the high temperature treatment of glass manufacturing and electronic microchip manufacturing, hydrogen is added in nitrogen atmosphere to remove residual oxygen. In petrochemical industry, crude oil needs to be hydrogenated by desulfurization and hydrocracking. Another important use of hydrogen is to hydrogenate fats in margarine, edible oil, shampoo, lubricant, household cleaner and other products. Because of its high fuel characteristics, liquid hydrogen is used as a fuel in aerospace industry.
[Edit this paragraph] Main uses and application industries
Uses: nuclear research, bombardment particles of deuterium accelerator, tracer. Application industries: petroleum refining, float glass, electronic food chemical production, aerospace automobile industry.
[Edit this paragraph] Packaging, storage and transportation
Packaging mode: hydrogen trailer/bottle group/steel cylinder transportation mode: there are four ways of hydrogen storage and transportation, namely gas storage and transportation, liquid storage and transportation, metal hydride storage and transportation and microsphere storage and transportation. At present, only the first three kinds are actually used, and the storage and transportation methods of microspheres are still under study.
[Edit this paragraph] Safety precautions
Hydrogen is a colorless, odorless, non-toxic, flammable and explosive gas, which is in danger of explosion when mixed with fluorine, chlorine, oxygen, carbon monoxide and air. Among them, the mixture of hydrogen and fluorine can spontaneously explode in low temperature and dark environment, and it can also explode in light when the mixing ratio with chlorine is 1: 1. Hydrogen is colorless and odorless, and the flame is transparent when burning, so its existence is not easily perceived by the senses. In many cases, ethanethiol is added to hydrogen for sensory detection, and the flame can be colored. Although hydrogen is non-toxic and physiologically inert to human body, if the hydrogen content in the air increases, it will cause hypoxia and suffocation. Like all cryogenic liquids, direct contact with liquid hydrogen can cause frostbite. Liquid hydrogen overflow and sudden large-scale evaporation will also cause environmental hypoxia, and may form an explosive mixture with air, causing combustion and explosion accidents.