Under normal conditions hydrogen is a colorless, odorless gas; gas molecules by a double atoms; melting point -259.14 ° C, the boiling point of -252.8 ° C, the critical temperature 33.19K, the critical pressure of 12.98 atmospheres, gas density 0.0899 g / l; water solubility 21.4 cm & sup3; / kg water (0 ° C), slightly soluble in organic solvents.
At room temperature, hydrogen relatively inactive, but can be used to make a suitable catalyst activation. At high temperatures, hydrogen is highly reactive. In addition to the rare gas element, almost all of the elements can form compounds with hydrogen. Hydrides is generally called a nonmetallic element hydrogen, such as hydrogen halide, hydrogen sulfide and the like; metal hydride element called metal hydrides, such as lithium hydride, calcium hydride.
Hydrogen is an important industrial raw material, but also the future of energy is the cleanest fuel.
The content of elements in the sun: (ppm) 7500000
Content of the crust: (ppm) 1500
At room temperature, hydrogen relatively inert, but can be the catalyst activation. The existence of a single hydrogen atom, there are strong reductive. Hydrogen at high temperatures is very lively. In addition to the rare gas element, almost all of the elements can form compounds with hydrogen.
Names, symbols, ID: hydrogen, H, 1
Series: Non-metallic
:( Atomic volume cc / mol) 14.4
Oxidation states: Main H + 1 Other H0, H-1
Family, period, zoning elements: Group 1, 1, s
Ionization energy (kJ / mol)
M - M + 1312
Density, Hardness: 0.0899 kg / m3 (273K), NA
Thermal conductivity: W / (m · K) 180.5
Bond energy: (kJ / mol)
H-H 454
H-F 566
H-Cl 431
H-Br 366
H-I 299
Cell parameters:
a = 470 pm
b = 470 pm
c = 340 pm
α = 90 °
β = 90 °
γ = 120 °
Color and Appearance: colorless
Sound propagation speed in which: (m / S) 1310
Image: H, 1.jpg
Atmospheric content: 0.0001%
Crustal content: 0.88%
Atomic Properties
Atomic weight: 1.00794 atomic mass units
Atomic radius :( calc) 25 (53) pm
Covalent radius: 37 pm
Van der Waals radius: 120 pm
Valence electron arrangement: 1s1
Electronic energy levels in each arrangement: 1
Price oxide (oxide): 1 (bisexual)
Crystal structure: Hexagonal
Physical Properties
Gaseous state of matter
Number of protons in the nucleus: 1
Extranuclear: 1
Nuclear audit: 1
Proton mass: 1.673E-27
Proton relative quality: 1.007
Respective period: 1
Number of affiliated group: IA
Molar mass: 1g / mol
Oxides: H2O
Highest price oxides: H2O
External electronic arrangement: 1s1
Extranuclear electron arrangement: 1
Colors and states: colorless gas
Atomic radius: 0.79
Common valence: +1, -1
Melting point: 14.025 K (-259.125 ° C)
Boiling point: 20.268 K (-252.882 ° C)
Molar volume: 22.4L / mol
Heat of vaporization: 0.44936 kJ / mol
Heat of fusion: 0.05868 kJ / mol
Vapor Pressure: 209 Pa (23K)
Sound velocity: 1270 m / s (293.15K)
Other properties
Electronegativity: 2.2 (Pauling scale)
Specific heat: 14304 J / (kg · K)
Conductivity: No data
Thermal conductivity: 0.1815 W / (m · K)
Ionization energy: 1312 kJ / mol
The most stable isotopes
Isotopic abundance of energy decay half-life decay mode
MeV decay products
1H 99.985% stable
2H 0.015% stable
3H 10-15% /
Artificial 12.32 on β decay 0.019 3He
4H artificial 9.93696 × 10-23 seconds neutron release 2.910 3H
5H artificial 8.01930 × 10-23 seconds neutron release 4H
6H artificial 3.26500 × 10-22 seconds three neutrons
Release? 3H
7H no artificial neutron data release?? 6H?
Nuclear magnetic resonance characteristic public
1H 2H 3H
Nuclear spin 1/2 1 1/2
Sensitivity 1 0.00965 1.21
distributed
The Earth and the atmosphere there is only a very few of the free state hydrogen. In the Earth's crust, if calculated according to weight, hydrogen is only 1% of the total weight, and if the calculated atomic percent, accounted for 17%. Hydrogen is widely distributed in nature, hydrogen is water "warehouse" - water containing 11% hydrogen; soil about 1.5% hydrogen; oil, natural gas, hydrogen also animals and plants. In the air, the hydrogen down much, of the total volume of 5/10000000. In the universe as a whole, in terms of atomic percentage, it is the most elemental hydrogen. According to the research, in the sun's atmosphere, the atomic percentage basis, accounting for 81.75% of hydrogen. In space, the number of hydrogen atoms and about 100 times larger than the total of all other elements of atoms.
preparation
Industrial production method: electrolysis of water 2H2O = O2 ↑ + 2H2 ↑
Laboratory Method: zinc and dilute hydrochloric reflect Zn + 2HCl = ZnCl2 + H2 ↑
Other Method: Fe + H2SO4 = FeSO4 + H2 ↑
Mg + H2SO4 = MgSO4 + H2 ↑
2Al + 3H2SO4 = Al2 (SO4) 3 + H2 ↑
Fe + 2HCl = FeCl2 + H2 ↑
Mg + 2HCl = MgCl2 + H2 ↑
Zn + 2HCl = ZnCl2 + H2 ↑
2Al + 6HCl = 2AlCl3 + 3H2 ↑
Industry Act electrolytic method, hydrocarbon cracking method, a method of hydrocarbon steam reforming, refinery gas extraction.
purification
With the development of the semiconductor industry, chemical industry and electric and optical fiber, resulting in a demand for high-purity hydrogen. For example, the semiconductor manufacturing process requires the use of more than 99.999% purity. But now all kinds of industrial hydrogen purity hydrogen production methods obtained is not high, in order to meet the demand for a variety of high purity hydrogen industry, the need for further purification of hydrogen gas. Hydrogen purification method can be broadly divided into two categories (physical and chemical methods), six methods.
Hydrogen purification method:
The method applies the basic principles of a feed gas obtained hydrogen purity (%) Applicable Standard
High-pressure catalytic catalytic reaction of hydrogen and oxygen and hydrogen to remove the oxygen-containing oxygen, mainly for electrolytic method of small hydrogen 99.999
Metal hydride hydrogen separation prior to the metal to form a metal hydride, followed by heating under reduced pressure or decomposed low hydrogen content gas> 99.9999 Small
High-pressure adsorption adsorbent selective adsorption of any impurity containing gas 99.999 big
Low temperature cryogenic separation of gas condensate any hydrogen-containing gas 90 to 98 large
Palladium alloy film diffusion method palladium alloy film selectively permeable to hydrogen, and other gases impermeable lower hydrogen content gas> 99.9999 Small
Polymer film diffusion method of gas diffusion rate through the film different refinery off-gas from 92 to 98 small

use
Hydrogen is an important industrial raw materials, such as the production of synthetic ammonia and methanol is also used to extract oil, hydrogenated organic substance as a contraction of the gas used in oxyhydrogen flame welding and rocket fuel. At elevated temperature with hydrogen reduction of metal oxides in the preparation of metal compared to other methods, the nature of the product easier to control, while the purity of the metal is also high. Widely used in tungsten, molybdenum, cobalt, germanium, and metal powder such as iron, silicon production.
Because hydrogen is very light, people use it to produce hydrogen balloon. When hydrogen and oxygen compounds and emit a lot of heat, being used to cut metal.
Use energy generated during nuclear fusion of hydrogen isotopes deuterium and tritium atoms can produce destruction and devastating hydrogen bomb, its much more powerful than the atomic bomb.
Now, hydrogen is also used as future clean energy one kind of substitutability for automobile fuel. To this end, the United States in 2002, also proposed a "national hydrogen program." But because technology is not mature, not yet conducted a large number of industrial applications. 2003 scientists discovered that the use of hydrogen fuel hydrogen atmosphere will increase by about 4 to 8 times. Think might make the same upper stratosphere colder, more clouds, but also aggravate the ozone hole. But some factors can offset this effect, reduce the use of chlorofluorocarbons such as methane, absorb the soil, and the development of new technologies such as fuel cells.
More expensive than gold water
Described above are ordinary hydrogen, its atomic weight is 1, it has two "do" big "brother" deuterium (sound knives) and tritium (Tone River) their atomic weight is 2 and 3 respectively. People sometimes refer to them as "heavy hydrogen" and "tritium", which combine to generate water and heavy water not call overweight water and oxygen.
The total water on Earth weighs about 14 billion tons, of which less than ten thousandths of heavy water. In order to obtain one kilogram of heavy water will consume 60,000 kWh of electricity and 101 tons of water, which is more than the cost of sand in the gold flower is much greater, and therefore the price of heavy water than Jin Zigui. Nature of the heavy water is very small, and even more overweight and less water in the wide expanse of the sea, one can not find even a billionth only by artificial means to manufacture. Generally the lithium metal in atomic reactors, under neutron bombardment, the lithium into tritium, then combines with oxygen to generate excess water. Manufacture one kilogram overweight tons of water to consume nearly atomic energy, and the production is very slow, but also a factory manufacturing year tens of kilograms overweight water, so the price of water overweight proportion of water is more expensive on the times, more expensive than gold dozens of times.
On the surface, heavy water and general water is no different. But temper quite different, if you use heavy water goldfish, not long after the fish will die, with heavy water soaked seeds will not germinate. Heavy water "head" than the big water, one cubic meter of heavy water than one cubic meter of water for a normal weight 105.6 kg. Ordinary water freezes at zero degrees, boiling at 100 ℃; and heavy water at 3.8 ℃ becomes ice, people call it "hot ice."
Although the production of heavy water and excess water takes up a great price, but people still continue to manufacture them. What happen?
They turned out to humans, there are many benefits. Speaking first heavy water, it radioactive, it's this characteristic, scientists can study the progress of certain biological or chemical processes. For example, allow patients to drink a little water containing a very small amount of overweight tea, half an hour later, you can check out the radioactivity from the urine, until 14 days later, radioactive disappear, indicating that the water in the human body residence time is 14 days. If you want to study a chemical process in the context of water, but not allowed to join something else to destroy the chemical reaction, then you can add some water in ordinary water overweight, overweight flow to where, where it appears radioactivity. Scientists can easily use the detector to measure its hiding place.
Heavy water atomic energy industry is an important role, it is the best atomic reactor moderator and the heating agent, after using it, you can greatly reduce the constituent atoms of the fuel. Heavy water is an important national defense materials, the polymerization reaction of the hydrogen bomb is to use it to manufacture, heavy hydrogen at very high temperatures will produce nuclei, where a strong explosion, its energy equivalent to several thousand ten thousand tons of high explosives. An ordinary hydrogen bomb could easily blow up a city. If it explode to release all the energy is converted into electrical energy, humans decades will not be exhausted!
Safety
Hydrogen is the lightest gas known gas. Hydrogen at normal temperature and pressure is a colorless, odorless flammable gas. It addition to lack of oxygen caused by suffocation, but also found no toxicity. Hydrogen and air, oxygen, halogens strong affinity. Hydrogen has a wide flammable range in air and oxygen. Hydrogen high flash point, but its ignition energy is very small, it can catch fire easily, at a small static spark can easily ignite. This is the nature of a special significance. When it can be exposed to heat from fire or combustion, and emit almost invisible flame. Hydrogen is a kind of high-energy fuel, when combined with air or other oxidizers fire way to heat or explosion releasing large amounts of energy, the ferocity of the reaction depends on combustion conditions. A mixture of hydrogen and halogen gas can explode in sunlight. Explosive range of hydrogen and nitrous oxide mixture of 5.2% to 80%, with a mixture of nitric oxide explosion in the range of 13.5% to 49%. This explosive hydrogen gas is extremely dangerous horrible characteristics. Hydrogen is very easy to spread and penetration of gas, it is very prone to leaks, and stays in good ceiling height.
Cryogenic hydrogen at room temperature and the density of hydrogen is different when it starts to evaporate from the liquid hydrogen is heavier than air and deposited on the ground, and so on after the warming began to spread. Cold fog of hydrogen gas can form when moist air encounters, and thus it can be seen in the proliferation of signs. But in the fog periphery can still be seen in the formation of explosive mixtures. If the hydrogen gas in the initial flash evaporation on fire, will produce fireballs.
Highly reducing hydrogen at high temperature with a metal oxide, a metal chloride to free the metal, so it is generally not corrosive. In the role of a catalyst such as platinum and the effect of reducing the organic compound aldehyde unsaturated hydrocarbons.
    C2H2 + H2- → C2H4
    C2H4 + H2- → C2H6
    CH3CHO + H2- → CH3CH2OH
    CH3COOC2H5 + 2H2- → 2CH3CH20H
    CH3COCH3 + H2- → CH3CH-CH3
                   | OH
But also between the lattice hydrogen immersion metal lattice expansion or deformation, resulting in a metallic material embrittlement. Steel produces the following decarburization reaction at high temperature and erosion by hydrogen.
    Fe3C + 2H2- → CH4 + 3Fe
    The transition metal can be hydrogen reversibly adsorbing or absorbing generated variable amounts of metal hydride. The amount of hydrogen is absorbed in the Pd, Pt, Ni, Ti, Fe, etc. are more of Pd, it can absorb 800 times its volume of hydrogen.
    Hydrogen slightly soluble in water, the absorption coefficient at 20 ℃ a is 0.0182.
    5. Toxicity
    Hydrogen itself is non-toxic, it is still the prototype discharge after inhalation. It is a choking agent, but examples in practical work because hydrogen gas suffocation deaths rarely, however, fires and explosions caused by the hydrogen gas has continued to occur. So the explosive nature of hydrogen should arouse enough attention.
    Usually after hydrogen filling packed in pressure cylinders or liquefied cryogenic containers. So in addition to the high-pressure hydrogen gas leak risk of fire or explosion, there was a cold liquid hydrogen burn hazard