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Hydrogen

 

Hydrogen
Physical Properties
Color  -  Colorless
Odor  -  Rotten-egg Odor
Density -  \(0.00000296 \; lb/in^3 \;(0.0000820 \; g/cc)\)
Molar Mass  -  \(2.016 \; g/mol \;(2.016 \; g/mol)\)
Vapor Pressure  -  \(75.0 \; torr \;\)@\(\; -433.5 \; F^\circ \; (0.1000 \;bar \;\)@\(\; -258.6 \; C^\circ)\)
Chemical Properties
Atomic Number  -  \(1\)
Chemical Formula  -  \(H_2\)
Atomic Mass  -  \(1.007825 \; amu \;(1.007825 \; amu)\)
State of Matter  -  Gas
Flammability  -  Highly Flammable
Electrical Properties
Dielectric Constant  -  \(1.228 \;\)@\(\; -423 \; F^\circ \;(1.228 \;\)@\(\; -253 \; C^\circ)\)
Thermal Properties
Melting Point  -  \(-434.81 \; F^\circ \; (-259.34 \; C^\circ)\)
Boiling Point  -  \(-423.17 \; F^\circ \; (-252.87 \; C^\circ)\)
Autoignition Temp.  -  \(932 \; F^\circ \; (500 \; C^\circ)\)
LFL  -  \(4.0 \;(4.0)\)%
UFL  -  \(75.0 \;(75.0)\)%
Heat of Fusion  -  \(25.6 \; BTU/lb \; (59.5 \; J/g)\)
Heat of Vaporization  -  \(192.0 \; BTU/lb \; (446.4 \; J/g)\)
Specific Heat Capacity  -  \(3.414 \; BTU/lbF^\circ \; (14.29 \; J/gC^\circ )\)
Thermal Conductivity  -  \(0.476 \;\)@\(\; 0.00 \;psi \;\)@\(\; -280 \; F^\circ \; (0.0686 \;\)@\(\; 0.00 \; MPa \;\)@\(\; -173 \; C^\circ )\)
Optical Properties
Refractive Index  -  \(1.1096 \;\)@\(\; -423 \; F^\circ \; (1.1096 \;\)@\(\; -253 \; C^\circ )\)
Hydrogen \(H_2\) is the simplest and most abundant chemical element in the universe, consisting of a single proton and a single electron in its most common form (protium).  It's a colorless, odorless, and tasteless gas, and despite its abundance in the cosmos (making up about 75% of all normal matter), it's relatively scarce in its elemental gaseous form on Earth.  This is because hydrogen readily combines with other elements to form compounds, most notably water (H₂O), but also hydrocarbons, ammonia, and other organic molecules crucial for life.

As a highly flammable gas, hydrogen can burn in air across a wide range of concentrations, and mixtures of hydrogen and oxygen can be explosive.  Its extremely low density and weak intermolecular forces give it the lowest melting and boiling points of all elements, except for helium.  While hydrogen is not an energy source itself, it is a versatile energy carrier, meaning it can store and deliver energy produced from other sources like natural gas, nuclear power, or renewables such as solar and wind.  It's increasingly seen as a key component in a low-carbon future, with potential applications in powering vehicles through fuel cells (producing only water as a byproduct), generating electricity, and decarbonizing heavy industries like steelmaking and chemical production by replacing fossil fuels.

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