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)

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Molecular weight

2.016
g/mol
Content in dry 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 (at boiling point)

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

/

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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)

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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

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H₂

Hydrogen

Safety & Compatibility

Information to safely use this molecule

Major hazards
Material compatibility

Safety

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 NBR

Satisfactory
Chloroprene

Satisfactory
Chlorofluorocarbons

Satisfactory
Silicon

Acceptable
strong rate of permeation
Perfluoroelastomers

Satisfactory
Fluoroelastomers

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.

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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 !