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Hydrogen
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Hydrogen
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H2
Hydrogen

Physical Properties

Under solid (grey), liquid (blue) and vapor states (white) along the equilibrium curves

  • General properties
  • Solid phase
  • Liquid Phase
  • Gas Phase
(P)
log(P)
Download
  • Molecular weight
    2.016
    g/mol
  • Content in air
    /

Critical Point

  • Temperature
    - 240.01
    °C
    - 400.018 °F 33.14 K
  • Pressure
    12.964
    bar
    1.2964E6 pa 188.0268 lbf/in2 12.7945 Atm 1296.4 Kpa 9723.8265 mmHg
  • Density
    31.263
    kg/m³
    1.9517 lb/ft³

Triple Point

  • Temperature
    - 259.19
    °C
    - 434.542 °F 13.96 K
  • Pressure
    7.7E-2
    bar
    7700 pa 1.1168 lbf/in2 7.5993E-2 Atm 7.7 Kpa 57.7549 mmHg
Pressure 1.013 bar
  • Melting point
    - 259.2
    °C
    - 434.56 °F 13.95 K
  • Latent heat of fusion (at melting point)
    58.089
    kJ/kg
    24.9905 Btu/lb 13.8836 kcal/kg
  • Solid density
    /
Pressure 1.013 bar
  • Liquid density
    70.849
    kg/m³
    4.4229 lb/ft³
  • Boiling point
    - 252.78
    °C
    - 423.004 °F 20.37 K
  • Latent heat of vaporization (at boiling point)
    448.69
    kJ/kg
    193.0314 Btu/lb 107.2395 kcal/kg
Pressure1.013barTemperature
  • Compressibility factor Z
    1.0006
    1.0006
    1.0006
  • Cp/Cv ratio γ
    1.4098
    1.4069
    1.4054
  • Dynamic viscosity
    8.3969E-5
    Po
    8.3969 µPa.s 8.3969E-6 PA.S 5.6425E-6 lb/ft/s
    8.7098E-5
    Po
    8.7098 µPa.s 8.7098E-6 PA.S 5.8527E-6 lb/ft/s
    8.9154E-5
    Po
    8.9154 µPa.s 8.9154E-6 PA.S 5.9909E-6 lb/ft/s
  • Gas density at boiling point
    1.333
    kg/m³
    8.3216E-2 lb/ft³
    1.333
    kg/m³
    8.3216E-2 lb/ft³
    1.333
    kg/m³
    8.3216E-2 lb/ft³
  • Gas density
    8.99E-2
    kg/m³
    5.6123E-3 lb/ft³
    8.52E-2
    kg/m³
    5.3189E-3 lb/ft³
    8.23E-2
    kg/m³
    5.1378E-3 lb/ft³
  • Heat capacity at constant pressure Cp
    14.1976
    kJ/(kg.K)
    3.3933 BTU/lb∙°F 1.4198E4 J/kg∙K 3.3933 kcal/kg∙K
    14.2676
    kJ/(kg.K)
    3.41 BTU/lb∙°F 1.4268E4 J/kg∙K 3.41 kcal/kg∙K
    14.3063
    kJ/(kg.K)
    3.4193 BTU/lb∙°F 1.4306E4 J/kg∙K 3.4193 kcal/kg∙K
  • Heat capacity at constant volume Cv
    10.0704
    kJ/(kg.K)
    2.4069 BTU/lb∙°F 1.007E4 J/kg∙K 2.4069 kcal/kg∙K
    10.1409
    kJ/(kg.K)
    2.4237 BTU/lb∙°F 1.0141E4 J/kg∙K 2.4237 kcal/kg∙K
    10.1796
    kJ/(kg.K)
    2.433 BTU/lb∙°F 1.018E4 J/kg∙K 2.433 kcal/kg∙K
  • Liquid (at boiling point)/gas equivalent
    788.41
    mol/mol
    831.17
    mol/mol
    860.55
    mol/mol
  • Solubility in water
    /
    1.51E-5
    mol/mol
    1.411E-5
    mol/mol
  • Specific gravity
    0.07
    0.07
    0.07
  • Specific volume
    11.128
    m³/kg
    178.2533 ft³/lb
    11.739
    m³/kg
    188.0406 ft³/lb
    11.983
    m³/kg
    191.9491 ft³/lb
  • Thermal conductivity
    172.58
    mW/m∙K
    9.9781E-2 Btu/ft/h/°F 1.4849 cal/hour∙cm∙°C 4.1248E-4 cal/s∙cm∙°C 1.7258E-1 W/(m∙K)
    180.05
    mW/m∙K
    1.041E-1 Btu/ft/h/°F 1.5492 cal/hour∙cm∙°C 4.3033E-4 cal/s∙cm∙°C 1.8005E-1 W/(m∙K)
    184.88
    mW/m∙K
    1.0689E-1 Btu/ft/h/°F 1.5907 cal/hour∙cm∙°C 4.4187E-4 cal/s∙cm∙°C 1.8488E-1 W/(m∙K)
  • Vapor pressure
    /
    /
    /
H2
Hydrogen

Liquid / Gas Volumes

Calculate a liquid or gas volume or a mass

Liquid Phase

At boiling point at 1.013 bar

m3(Volume)
kg(Mass)

Gas Phase

at 1.013 bar and boiling point

m3(Volume)
kg(Mass)
H2
Hydrogen

Applications

Examples of uses of this molecule in Industry and Healthcare

Aeronautics

Aviation companies are currently testing and examining the potential for using hydrogen to replace the Auxiliary Power Units (APUs) and use fuel cells to generate electrical power for non-essential aircraft applications.

Aeronautics

Space

Liquid hydrogen is used as rocket or Lancher propellant. In combination with an oxidizer such as liquid oxygen, liquid hydrogen yields the highest specific impulse, or efficiency in relation to the amount of propellant consumed of any known rocket propellant.

Space

Automotive

Hydrogen is also a carbon-free fuel to electric vehicles. An on-board hydrogen tank and fuel cell are used to respectively store the hydrogen and produce electricity for the car vehicle. Hundreds of hydrogen forklifts, cars and buses are already in service. Hydrogen is used for metal heat treatment in vehicles. It is also used in mixtures for arc and plasma welding of stainless steels.

Automotive

Chemicals

Hydrogen is used for the synthesis of amines (e.g. aniline) or alkanes from alkenes (e.g. cyclohexane) via hydrogenation reactions. Hydrogen is used for methanol production from synthesis gas, a mixture of hydrogen and carbon monoxide. It is an important starting point to produce valuable products such as dimethyl ether (DME) and propylene that are important sources of industrial chemicals and plastic products.

Chemicals

Electronic components

Hydrogen is a carrier gas in semiconductor processes, especially for silicon deposition and crystal growing. It is also a scavenger gas in atmosphere soldering as well as for annealing of copper films. Hydrogen allows a complete elimination of oxygen and its inconveniences in medium to high temperature processes when used as forming gas (hydrogen diluted in nitrogen). Hydrogen provides a reducing atmosphere while mixing reactive molecules.

Electronic components

Food

Hydrogen is used for the hydrogenation of amines and fatty acids for food solid fats production.

Food

Glass

Hydrogen mixed with nitrogen creates a reductive atmosphere over the tin bath in glass production process preventing oxygen to react with the tin. Hydrogen is used in heat treatment (oxy-hydrogen flame) of hollow glass and optic fibers pre-forms.

Glass

Laboratories & Research Centers

Hydrogen is a carrier gas in gas chromatography and in various analytical instrument applications. It helps move the substance to analyse through the process.

Laboratories & Research Centers

Metal

Hydrogen, mixed with protective inert gases (H2 diluted in nitrogen) eliminates all oxygen traces, harmful for these medium and high temperature processes. Hydrogen, mixed with nitrogen, is used for metal heat treatment. Heat treatment is a sequence of heating operations applied to metals - sheets, tubes, wires or parts - to improve their mechanical properties, by modifying their structure or composition. Hydrogen is also used in mixtures for arc or plasma welding of stainless steels.

Metal

Oil & Gas

Hydrogen is used in refinery to remove sulfur from petroleum products (hydrodesulfurization process), thus reduce sulfur dioxide emissions during fuel combustion and prevent acid rain. Hydrogen is used in many other units in refineries : to crack long-chain hydrocarbons into lighter hydrocarbons (hydrocracking process), to convert normal paraffins into iso-paraffins and improve the product properties (hydroisomerisation) and to remove aromatic compounds from a mixture, especially as part of the oil refining process (dearomatisation).

Oil & Gas

Other

Hydrogen fuel cells can be used as clean and autonomous power supply for off-grid sites, such as telecommunication stations and to power residential homes.

Photonics

Hydrogen is used in the fabrication of fibre optic as a high purity gas.

Photonics
H2
Hydrogen

Safety

Information to safely use this molecule

  • Major hazards
  • Material compatibility
  • GHS02
    Flammable
  • GHS04
    Gas under pressure

Autoignition Temperature in Air at Patm and Flammability Limits in Air at Patm and 293.15 K (except if the temperature is indicated)

  • Europe (according to EN1839 for Limits and EN 14522 for autoignition temperature)

    • Auto-ignition temperature
      560
      °C
      1040 °F 833.15 K
    • Flash point
      /
    • Lower flammability limit
      4
      vol/%
      4.E4 ppm 4.E4 ppm 0.04 vol/vol
    • Upper flammability limit
      77
      vol/%
      7.7E5 ppm 7.7E5 ppm 0.77 vol/vol
  • US (according to NFPA for Limits and ASTM E659 for autoignition temperature)

    • Auto-ignition temperature
      500
      °C
      932 °F 773.15 K
    • Flash point
      /
    • Lower flammability limit
      4
      vol/%
      4.E4 ppm 4.E4 ppm 0.04 vol/vol
    • Upper flammability limit
      75
      vol/%
      7.5E5 ppm 7.5E5 ppm 0.75 vol/vol

Odor

none

Metals

  • Aluminium
    Satisfactory
  • Brass
    Satisfactory
  • Monel
    Satisfactory
  • Copper
    Satisfactory
  • Ferritic Steel
    Satisfactory
    risk of embrittlement
  • Stainless steel
    Satisfactory
    risk of embrittlement
  • Zinc
    Satisfactory
  • Titanium
    Satisfactory
    risk of embrittlement

Plastics

  • Polytetrafluoroethylene
    Acceptable
    strong rate of permeation
  • Polychlorotrifluoroethylene
    Satisfactory
  • Polyvinylidene fluoride
    Satisfactory
  • Polyvinyl chloride
    Satisfactory
  • Ethylene tetrafluoroethylene
    Satisfactory
  • Polycarbonate
    Satisfactory
  • Polyamide
    Satisfactory
  • Polypropylene
    Acceptable
    strong rate of permeation

Elastomers

  • Buthyl (isobutene- isoprene) rubber
    Satisfactory
  • Nitrile rubber
    Satisfactory
  • Chloroprene
    Satisfactory
  • Chlorofluorocarbons
    Satisfactory
  • Silicon
    Acceptable
    strong rate of permeation
  • Perfluoroelastomers
    Satisfactory
  • Fluoroelastomers
    Satisfactory
  • Nitrile rubber
    Satisfactory
  • Neoprene
    Satisfactory
  • Polyurethane
    Satisfactory
  • Ethylene-Propylene
    Satisfactory

Lubricants

  • Hydrocarbon based lubricant
    Satisfactory
  • Fluorocarbon based lubricant
    Satisfactory

Materials compatibility

Recommendations : Air Liquide has gathered data on the compatibility of gases with materials to assist you in evaluating which materials to use for a gas system. Although the information has been compiled from what Air Liquide believes are reliable sources (International Standards: Compatibility of cylinder and valve materials with gas content; Part 1- Metallic materials: ISO11114-1 (March 2012), Part 2 - Non-metallic materials: ISO11114-2 (April 2013), it must be used with extreme caution and engineering judgement. No raw data such as these can cover all conditions of concentration, temperature, humidity, impurities and aeration. It is therefore recommended that this table is only used to identify possible materials for applications at high pressure and ambient temperature. Extensive investigation and testing under the specific conditions of use need to be carried out to validate a material selection for a given application. Contact the regional Air Liquide team for expertise service.

H2
Hydrogen

Learn More

General information

More information

Hydrogen was discovered by Henry Cavendish in 1766. It owes its name to Antoine Laurent de Lavoisier, who combined the Greek "hydor", "water", and "genen", "to engender". Hydrogen is colorless, very light, and reacts easily with other chemical substances making it a very useful reactant for the chemical and oil industries. Hydrogen is found in the atmosphere at trace levels. In 1970, hydrogen fluxes have been detected in the oceans, resulting from serpentinization of rocks but the exploitation seems unlikely due to extreme geological conditions. More recently, natural hydrogen emissions from the ground have also been detected and are under investigation to understand the origin of this hydrogen. Today natural gas or hydrocarbons as well as water are used as raw materials to produce hydrogen. Moreover, hydrogen has a very high energy content (120 MJ/kg) while containing no carbon atom. This makes it a promising energy vector for the future. Associated to air or oxygen in a fuel cell, hydrogen is converted in electricity and heat, releasing only water. Driving an electric car over a long distance with no emission is a dream of many !