Chemical properties of hydrogen - Health effects of hydrogen - Environmental effects of hydrogen
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Hydrogen Atom MassBy: Mr. Pradeep Kshetrapal, Tutorials Point India Private Limited.
HydrogenFirst element in the periodic table. In normal conditions it’s a colourless, odourless and insipid gas, formed by diatomic molecules, H2. The hydrogen atom, symbol H, is formed by a nucleus with one unit of positive charge and one electron. Its atomic number is 1 and its atomic weight 1,00797 g/mol. It’s one of the main compounds of water and of all organic matter, and it’s widely spread not only in The Earth but also in the entire Universe. There are three hydrogen isotopes: protium, mass 1, found in more than 99,985% of the natural element; deuterium, mass 2, found in nature in 0.015% approximately, and tritium, mass 3, which appears in small quantities in nature, but can be artificially produced by various nuclear reactions. Uses: The most important use of hydrogen is the ammonia synthesis. The use of hydrogen is extending quickly in fuel refinement, like the breaking down by hydrogen (hydrocracking), and in sulphur elimination. Huge quantities of hydrogen are consumed in the catalytic hydrogenation of unsaturated vegetable oils to obtain solid fat. Hydrogenation is used in the manufacture of organic chemical products. Huge quantities of hydrogen are used as rocket fuels, in combination with oxygen or fluor, and as a rocket propellent propelled by nuclear energy. Properties: Common hydrogen has a molecular weight of 2,01594 g. As a gas it has a density of 0.071 g/l at 0ºC and 1 atm. Its relative density, compared with that of the air, is 0.0695. Hydrogen is the most flammable of all the known substances. Hydrogen is slightly more soluble in organic solvents than in water. Many metals absorb hydrogen. Hydrogen absorption by steel can result in brittle steel, which leads to fails in the chemical process equipment. At normal temperature hydrogen is a not very reactive substance, unless it has been activated somehow; for instance, by an appropriate catalyser. At high temperatures it’s highly reactive. Although in general it’s diatomic, molecular hydrogen dissociates into free atoms at high temperatures. Atomic hydrogen is a powerful reductive agent, even at ambient temperature. It reacts with the oxides and chlorides of many metals, like silver, copper, lead, bismuth and mercury, to produce free metals. It reduces some salts to their metallic state, like nitrates, nitrites and sodium and potassium cyanide. It reacts with a number of elements, metals and non-metals, to produce hydrides, like NAH, KH, H2S and PH3. Atomic hydrogen produces hydrogen peroxide, H2O2, with oxygen. Atomic hydrogen reacts with organic compounds to form a complex mixture of products; with etilene, C2H4, for instance, the products are ethane, C2H6, and butane, C4H10. The heat released when the hydrogen atoms recombine to form the hydrogen molecules is used to obtain high temperatures in atomic hydrogen welding. Hydrogen reacts with oxygen to form water and this reaction is extraordinarily slow at ambient temperature; but if it’s accelerated by a catalyser, like platinum, or an electric spark, it’s made with explosive violence.
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In kilograms, the mass of a hydrogen atom is 1.67 times 10 to the power of negative 27 or 1.67 x 10-24 grams. Virtual villagers 5 download free. full version mac. That conversion is based on one atomic measurement unit of atomic mass for an atom of hydrogen. In grams, the mass of an atom of hydrogen is expressed as 1.67 x 10 -24. The original standard of atomic weight, established in the 19th century, was hydrogen, with a value of 1. From about 1900 until 1961, oxygen was used as the reference standard, with an assigned value of 16. The unit of atomic mass was thereby defined as 1/16 the mass of an oxygen atom. Atomic Weights and Isotopic Compositions for Hydrogen Isotope Relative Atomic Mass Isotopic Composition Standard Atomic Weight Notes: 1: H: 1: 1.007 825 032 23(9). Find the abundance of natural isotopes and atomic weights of the elements quickly. Mass Spectrometry, Scientific Supplies & Manufacturing. Hydrogen: H(1) 1.
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| Isotope | Atomic mass (Da) | Isotopic abundance (amount fraction) |
|---|---|---|
| 1H | 1.007 825 0322(6) | [0.999 72, 0.999 99] |
| 2H | 2.014 101 7781(8) | [0.000 01, 0.000 28] |
The major stable isotope ¹H is also known as protium. The minor stable isotope ²H is known asdeuterium, with symbol D. The low concentration of ²H in normal sources of hydrogen may have delayed itsdiscovery until 1931 when hydrogen isotope fractionation was demonstrated by distillation, electrolysis, evaporation,and in environmental samples. The atomic weight of hydrogen has been based on mass-spectrometricmeasurements since 1938. In its report for 1961, CIAAW recommended Ar(H) = 1.007 97(1) basedon the average and the range of ²H concentrations measured in hydrogen extracted from fresh- and saltwaters; however, it was noted that substances other than water could have a wider range of atomicweights.
The currently accepted best measurement of the isotopic composition of hydrogen from asingle natural source was performed on VSMOW (distributed by the IAEA and NIST), the referencematerial endorsed by CIAAW as the basis of the delta scale for relative isotope-ratio measurements. According to this measurement, VSMOW has an amount fraction of x(²H) = 0.000 155 74(5), correspondingto Ar(H)VSMOW = 1.007 981 75(5). The uncertainty of that value corresponds to a δ²H uncertaintyof 0.3 ‰, which is equal to or slightly smaller than typical uncertainties of most relative isotope-ratio measurements of H. Variations in the isotopic composition of hydrogen in chemicals and naturalterrestrial systems are known to exceed +1000 ‰, which is much larger than the uncertainty due to isotope-ratio measurements.
For water sources, the range of published δ²H values extends from −495 ‰ (Ar(H) = 1.007 9042), to +129 ‰ (Ar(H) =1.008 0020). Seawater, the largest reservoir of water near the Earth's surface, has a relatively uniformisotopic composition and atomic weight near that of VSMOW; whereas precipitation, polar ice,lakes, rivers, and groundwaters have atomic weights that range widely, generally decreasing with latitudeand elevation and increasing with evaporation. The highest δ²H value reported for a material ofnatural terrestrial origin is +180 ‰ for atmospheric H2. An unusual anthropogenic occurrence ofwater from a H2S well yielded δ²H values as high as +375 ‰ (Ar(H)= 1.008 0404). Hydrogen samples with low atomic weights, some of which are outside the range of the standard atomic-weight uncertainties, have been reported from some types of natural and artificialH2 gases, hence the annotation 'g'. The naturally occurring hydrogen sample with the lowest atomicweight (δ2H = −836 ‰ and Ar(H) = 1.007 8507) is H2 gas collectedfrom a natural gas well in Kansas, USA. That sample, and other similar ²H-depleted H2-rich naturalgases elsewhere, may have formed by natural chemical reduction of water during low-temperaturereactions with ultramafic (Fe-Mg-silicate) rocks. Hydrogen gases produced artificially by electrolysisand as by-products of petrochemical processing commonly are depleted in ²H. Though not natural,those gases are considered to be important because they are used commonly in laboratories.Commercial tank H2 has been reported to have δ²H as low as −813 ‰ (Ar(H) = 1.007 8543).
The radioactive isotope ³H, also known as tritium with symbol T, decays by negative beta emissionto ³He with a half-life of 12.3 years. Tritium is formed naturally in the atmosphere by cosmic-rayreactions such as 14N(n,t)12C and artificially in nuclear reactors. Large quantities of tritium were injectedinto the atmosphere as a by-product of thermonuclear bomb tests, mostly in the 1950s and 1960s.Tritium reacts in the atmosphere to form HTO and other compounds that are distributed with widelyvarying concentrations in the near-surface environment of the earth. Those variations, and other localanthropogenic ³H anomalies, are used commonly in environmental studies; however, concentrations oftritium in normal sources of hydrogen are too low by several orders of magnitude to have a measurable effect onthe atomic weight of hydrogen.
Atomic weights of the elements 2009 by M.E. Wieser and T.B. Coplen. Pure Appl. Chem. 2011 (83) 359-396
CIAAW
Hydrogen
Ar(H) = [1.007 84, 1.008 11] since 2009
The name derives from the Greek hydro for 'water' and genes for 'forming' because it burned in airto form water. Hydrogen was discovered by the English physicist Henry Cavendish in 1766.
Atomic Mass Of Hydrogen In Grams
Natural variations of hydrogen isotopic composition
Atomic Mass Of Hydrogen In Kg
Isotopic reference materials of hydrogen.