Difference between revisions of "Hydrogen"
| Line 19: | Line 19: | ||
|alt names= | |alt names= | ||
|allotropes= | |allotropes= | ||
| − | |appearance= | + | |appearance=Colorless gas |
<!-- Periodic table --> | <!-- Periodic table --> | ||
|above= | |above= | ||
| − | |below= | + | |below=[[Lithium|Li]] |
|left= | |left= | ||
| − | |right= | + | |right=[[Helium]] |
| − | |number= | + | |number=1 |
| − | |atomic mass= | + | |atomic mass=1.008 |
|atomic mass 2= | |atomic mass 2= | ||
|atomic mass ref= | |atomic mass ref= | ||
| Line 34: | Line 34: | ||
|series comment= | |series comment= | ||
|series color= | |series color= | ||
| − | |group= | + | |group=1 |
|group ref= | |group ref= | ||
|group comment= | |group comment= | ||
| − | |period= | + | |period=1 |
|period ref= | |period ref= | ||
|period comment= | |period comment= | ||
| − | |block= | + | |block=s |
|block ref= | |block ref= | ||
|block comment= | |block comment= | ||
| − | |electron configuration= | + | |electron configuration=1s<sup>1</sup> |
|electron configuration ref= | |electron configuration ref= | ||
|electron configuration comment= | |electron configuration comment= | ||
| − | |electrons per shell= | + | |electrons per shell=1 |
|electrons per shell ref= | |electrons per shell ref= | ||
|electrons per shell comment= | |electrons per shell comment= | ||
<!-- Physical properties --> | <!-- Physical properties --> | ||
|physical properties comment= | |physical properties comment= | ||
| − | |color= | + | |color=Colorless gas |
| − | |phase= | + | |phase=Gas |
|phase ref= | |phase ref= | ||
|phase comment= | |phase comment= | ||
| − | |melting point K= | + | |melting point K=13.99 K |
| − | |melting point C= | + | |melting point C=−259.16 |
| − | |melting point F= | + | |melting point F=−434.49 |
|melting point ref= | |melting point ref= | ||
|melting point comment= | |melting point comment= | ||
| − | |boiling point K= | + | |boiling point K=20.271 |
| − | |boiling point C= | + | |boiling point C=−252.879 |
| − | |boiling point F= | + | |boiling point F=−423.182 |
|boiling point ref= | |boiling point ref= | ||
|boiling point comment= | |boiling point comment= | ||
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|sublimation point ref= | |sublimation point ref= | ||
|sublimation point comment= | |sublimation point comment= | ||
| − | |density gplstp= | + | |density gplstp=0.08988 |
|density gplstp ref= | |density gplstp ref= | ||
|density gplstp comment= | |density gplstp comment= | ||
| Line 82: | Line 82: | ||
|density gpcm3nrt 3 ref= | |density gpcm3nrt 3 ref= | ||
|density gpcm3nrt 3 comment= | |density gpcm3nrt 3 comment= | ||
| − | |density gpcm3mp= | + | |density gpcm3mp=0.07 |
|density gpcm3mp ref= | |density gpcm3mp ref= | ||
| − | |density gpcm3mp comment= | + | |density gpcm3mp comment=(solid: 0.0763 g/cm<sup>3</sup>) |
| − | |density gpcm3bp= | + | |density gpcm3bp=0.07099 |
|density gpcm3bp ref= | |density gpcm3bp ref= | ||
|density gpcm3bp comment= | |density gpcm3bp comment= | ||
| Line 92: | Line 92: | ||
|molar volume ref= | |molar volume ref= | ||
|molar volume comment= | |molar volume comment= | ||
| − | |triple point K= | + | |triple point K=13.8033 |
| − | |triple point kPa= | + | |triple point kPa=7.041 |
|triple point ref= | |triple point ref= | ||
|triple point comment= | |triple point comment= | ||
| Line 100: | Line 100: | ||
|triple point 2 ref= | |triple point 2 ref= | ||
|triple point 2 comment= | |triple point 2 comment= | ||
| − | |critical point K= | + | |critical point K=32.938 |
| − | |critical point MPa= | + | |critical point MPa=1.2858 |
|critical point ref= | |critical point ref= | ||
|critical point comment= | |critical point comment= | ||
| − | |heat fusion= | + | |heat fusion=0.117 |
|heat fusion ref= | |heat fusion ref= | ||
|heat fusion comment= | |heat fusion comment= | ||
| Line 110: | Line 110: | ||
|heat fusion 2 ref= | |heat fusion 2 ref= | ||
|heat fusion 2 comment= | |heat fusion 2 comment= | ||
| − | |heat vaporization= | + | |heat vaporization=0.904 |
|heat vaporization ref= | |heat vaporization ref= | ||
|heat vaporization comment= | |heat vaporization comment= | ||
| − | |heat capacity= | + | |heat capacity=28.836 |
|heat capacity ref= | |heat capacity ref= | ||
|heat capacity comment= | |heat capacity comment= | ||
| Line 123: | Line 123: | ||
|vapor pressure 100= | |vapor pressure 100= | ||
|vapor pressure 1 k= | |vapor pressure 1 k= | ||
| − | |vapor pressure 10 k= | + | |vapor pressure 10 k=15 |
| − | |vapor pressure 100 k= | + | |vapor pressure 100 k=20 |
|vapor pressure ref= | |vapor pressure ref= | ||
|vapor pressure comment= | |vapor pressure comment= | ||
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<!-- Atomic properties --> | <!-- Atomic properties --> | ||
|atomic properties comment= | |atomic properties comment= | ||
| − | |oxidation states= | + | |oxidation states='''−1''', '''+1''' |
|oxidation states ref= | |oxidation states ref= | ||
| − | |oxidation states comment= | + | |oxidation states comment=(an amphoteric oxide) |
| − | |electronegativity= | + | |electronegativity=2.20 |
|electronegativity ref= | |electronegativity ref= | ||
|electronegativity comment= | |electronegativity comment= | ||
| − | |ionization energy 1= | + | |ionization energy 1=1312.0 |
|ionization energy 1 ref= | |ionization energy 1 ref= | ||
|ionization energy 1 comment= | |ionization energy 1 comment= | ||
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|atomic radius calculated ref= | |atomic radius calculated ref= | ||
|atomic radius calculated comment= | |atomic radius calculated comment= | ||
| − | |covalent radius= | + | |covalent radius=31±5 |
|covalent radius ref= | |covalent radius ref= | ||
|covalent radius comment= | |covalent radius comment= | ||
| − | |Van der Waals radius= | + | |Van der Waals radius=120 |
|Van der Waals radius ref= | |Van der Waals radius ref= | ||
|Van der Waals radius comment= | |Van der Waals radius comment= | ||
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|crystal structure prefix= | |crystal structure prefix= | ||
|crystal structure ref= | |crystal structure ref= | ||
| − | |crystal structure comment= | + | |crystal structure comment=Hexagonal |
|crystal structure 2= | |crystal structure 2= | ||
|crystal structure 2 prefix= | |crystal structure 2 prefix= | ||
|crystal structure 2 ref= | |crystal structure 2 ref= | ||
|crystal structure 2 comment= | |crystal structure 2 comment= | ||
| − | |speed of sound= | + | |speed of sound=1310 |
|speed of sound ref= | |speed of sound ref= | ||
| − | |speed of sound comment= | + | |speed of sound comment=(gas, 27 °C) |
|speed of sound rod at 20= | |speed of sound rod at 20= | ||
|speed of sound rod at 20 ref= | |speed of sound rod at 20 ref= | ||
| Line 191: | Line 191: | ||
|thermal expansion at 25 ref= | |thermal expansion at 25 ref= | ||
|thermal expansion at 25 comment= | |thermal expansion at 25 comment= | ||
| − | |thermal conductivity= | + | |thermal conductivity=0.1805 |
|thermal conductivity ref= | |thermal conductivity ref= | ||
|thermal conductivity comment= | |thermal conductivity comment= | ||
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|Curie point ref= | |Curie point ref= | ||
|Curie point comment= | |Curie point comment= | ||
| − | |magnetic ordering= | + | |magnetic ordering=Diamagnetic |
|magnetic ordering ref= | |magnetic ordering ref= | ||
|magnetic ordering comment= | |magnetic ordering comment= | ||
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|Brinell hardness ref= | |Brinell hardness ref= | ||
|Brinell hardness comment= | |Brinell hardness comment= | ||
| − | |CAS number= | + | |CAS number=12385-13-6 |
|CAS number ref= | |CAS number ref= | ||
| − | |CAS number comment= | + | |CAS number comment=1333-74-0 (H<sub>2</sub>) |
<!-- History --> | <!-- History --> | ||
|naming= | |naming= | ||
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|prediction date ref= | |prediction date ref= | ||
|prediction date= | |prediction date= | ||
| − | |discovered by= | + | |discovered by=Henry Cavendish |
|discovery date ref= | |discovery date ref= | ||
| − | |discovery date= | + | |discovery date=1766 |
|first isolation by= | |first isolation by= | ||
|first isolation date ref= | |first isolation date ref= | ||
|first isolation date= | |first isolation date= | ||
|discovery and first isolation by= | |discovery and first isolation by= | ||
| − | |named by= | + | |named by=Antoine Lavoisier |
|named date ref= | |named date ref= | ||
| − | |named date= | + | |named date=1783 |
|history comment label= | |history comment label= | ||
|history comment= | |history comment= | ||
Revision as of 16:12, 16 October 2017
| General properties | |||||
|---|---|---|---|---|---|
| Name, symbol | Hydrogen, H | ||||
| Appearance | Colorless gas | ||||
| Hydrogen in the periodic table | |||||
| |||||
| Atomic number | 1 | ||||
| Standard atomic weight (Ar) | 1.008 | ||||
| Group, block | , s-block | ||||
| Period | period 1 | ||||
| Electron configuration | 1s1 | ||||
per shell | 1 | ||||
| Physical properties | |||||
| Colorless gas | |||||
| Phase | Gas | ||||
| Melting point | 13.99 K K (−259.16 °C, −434.49 °F) | ||||
| Boiling point | 20.271 K (−252.879 °C, −423.182 °F) | ||||
| Density at (0 °C and 101.325 kPa) | 0.08988 g/L | ||||
| when liquid, at | 0.07 g/cm3 (solid: 0.0763 g/cm3) | ||||
| when liquid, at | 0.07099 g/cm3 | ||||
| Triple point | 13.8033 K, 7.041 kPa | ||||
| Critical point | 32.938 K, 1.2858 MPa | ||||
| Heat of fusion | 0.117 kJ/mol | ||||
| Heat of | 0.904 kJ/mol | ||||
| Molar heat capacity | 28.836 J/(mol·K) | ||||
| pressure | |||||
| Atomic properties | |||||
| Oxidation states | −1, +1 (an amphoteric oxide) | ||||
| Electronegativity | Pauling scale: 2.20 | ||||
| energies | 1st: 1312.0 kJ/mol | ||||
| Covalent radius | 31±5 pm | ||||
| Van der Waals radius | 120 pm | ||||
| Miscellanea | |||||
| Crystal structure | Hexagonal | ||||
| Speed of sound | 1310 m/s (gas, 27 °C) | ||||
| Thermal conductivity | 0.1805 W/(m·K) | ||||
| Magnetic ordering | Diamagnetic | ||||
| CAS Registry Number | 12385-13-6 1333-74-0 (H2) | ||||
| History | |||||
| Discovery | Henry Cavendish (1766) | ||||
| Named by | Antoine Lavoisier (1783) | ||||
Hydrogen is an element with the symbol H and the atomic number 1. It is a colorless, light gas at room temperature, and with most hydrogen atoms consisting of a single proton and electron, they are the simplest possible atoms in the universe. Some atoms may have one or two neutrons in their nucleus, forming the isotopes deuterium and tritium.
Contents
Properties
Physical properties
Hydrogen is a very light gas, with an atomic mass of 1.00797 and a density of 0.08988 g/L. Balloons filled with hydrogen will readily rise. Producing liquid hydrogen is completely infeasible to the amateur, but it has one of the highest energy densities of all fuels per mass. Hydrogen normally exists as a diatomic gas, which has two spin isomers: orthohydrogen and parahydrogen.
Pure hydrogen has no smell, but if the gas is freshly prepared from acids and zinc, or alkali and aluminium, it may have a pungent smell because of corrosive droplets or acid vapors carried by it.
Chemical properties
Hydrogen will form compounds with many different elements. Combustion with hydrogen produces water and a large amount of heat, light and sound. With fluorine, the corresponding redox reaction occurs explosively when the gases contact each other, forming hydrogen fluoride. Hydrogen and chlorine will react explosively on exposure to ultraviolet light to form hydrogen chloride, which can be dissolved in water to form hydrochloric acid. Bromine and iodine need sufficient activation energy to form their respective hydrogen halides. Some metals will react with hydrogen to form hydrides. Others alloy with the gas - palladium is notable for being able to absorb 900 times its weight in hydrogen.
With the proper catalyst (palladium, platinum, or Raney nickel) alkene and alkyne functionality can be converted to alkane functionality. With Lindlar's catalyst, a poisoned variant, alkynes can be reduced only to alkenes.
In air, hydrogen burns with a flame that is very dimly bluish in darkness and invisible under any kind of light. If hydrogen is freshly prepared, gasiform or aerosol contaminants may color the flame and make it visible; for example, hydrogen made by reacting aluminium with sodium hydroxide produces a sodium yellow flame.
Availability
Hydrogen is available as compressed gas in cylinders, though it's availability varies.
An important thing to remember is that hydrogen must NEVER be stored in other common gas cylinders, such as propane tanks. The presence of oxygen in the cylinder poses a risk when liquifying the gas inside. Hydrogen liquifies at 800 atm, a pressure difficult to achieve by an amateur chemist. Lastly, hydrogen will also cause embrittlement in many types of steels, such as high-strength and low-alloy steels, as well as titanium and nickel alloys.
Preparation
Hydrogen gas can be liberated by dissolving any sufficiently electropositive metal in a non-oxidizing acid, such as hydrochloric acid or dilute sulfuric acid. Normally, aluminium, magnesium or zinc are used for this process. The acid can also be replaced with a strong base, such as sodium hydroxide, but this will only work with amphoteric metals that can form hydroxometalate salts with sodium, such as aluminium and zinc; purely basic metals such as magnesium will not work. All these reactions produce large amounts of heat and may pose a fire or explosion hazard.
Another way to produce hydrogen is to electrolyze water with a small amount of electrolyte. Hydrogen gas is produced at the anode and oxygen is produced at the cathode.
Projects
- Hydrogen balloons
- Metal hydrides
- Reduction of organic compounds
- Ammonia synthesis
Handling
Safety
Hydrogen poses an asphyxiant hazard at high concentrations, in closed environments. When mixed with air, it poses a great explosive hazard in concentrations from 5% to 95% by volume.
Storage
Compressed and cryogenic hydrogen should only be stored in cylinders made of metal that is not susceptible to embrittlement. The cylinders should be checked from time to time for signs of corrosion and to make sure the valves work properly. They must also be stored in dark cold places, away from any heat source, and if possible in a semi-open space to prevent a possible build-up.
Due to the very small size of diatomic hydrogen, hydrogen can easily diffuse out of many materials such as latex. Thus, filling a balloon with hydrogen should be done only when you plan to use the balloon.
Disposal
Hydrogen can be safely released in open air. Ignition of the hydrogen may be preferable to prevent an unexpected explosion from occurring. This however, should never be done in a closed environment, as even a small amount of hydrogen in the air can cause a fire or explosion. Continuous venting is highly recommended.
