Hydrogen
Hydrogen is the most abundant element in the universe. It is also the lightest element and is so light and diffusive that uncombined hydrogen can escape from the atmosphere. Hydrogen gas ordinarily is a mixture of two molecular forms, ortho- and para-hydrogen, which differ by the spins of their electrons and nuclei. Normal hydrogen at room temperature consists of 25% of the para form and 75% of the ortho form.
Properties
- Highly flammable
- Colourless
- Odourless
- Non-toxic
Applications
- Used as a chemical reagent in the chemical and pharmaceutical industries
- Controlled atmospheres for heat treatment
- Because of its light weight, hydrogen is used for cooling in rotating machinery (e.g. electricity generators)
- Hydrogen is important in the proton-proton reaction and carbon-nitrogen cycle. Liquid hydrogen is used in cryogenics and in the study of superconductivity. Great quantities are used for the fixation of nitrogen from the air in the Haber ammonia process. Hydrogen is use in welding, for the hydrogenation of fats and oils, in methanol production, in hydrodealkylation, hydrocracking, and hydrodesulfurization. Other applications include producing rocket fuel, filling balloons, making fuel cells, producing hydrochloric acid, and reducing metallic ores.
Physical Properties
Hydrogen, symbol H, is one of the atoms making up water and also one of the atoms in all hydrocarbons and is therefore readily available everywhere on the earth. Hydrogen has an atomic number of 1.
| Gas | Hydrogen |
| Chemical formula | H2 |
| Molecular weight | 2.0 |
| Gas density | 0.08988 Kg/m3 |
| SG vapour | 0.07 |
| Boiling point | -253°C |
| Critical temperature | -240°C |
| Critical pressure | 12.98 bar |
Production
Hydrogen occurs in the free state in volcanic gases and some natural gases. Hydrogen is produced by electrolysis of water and is collected at the negative electrode (cathode). It is also prepared by steam on heated carbon, decomposition of certain hydrocarbons with heat, action of sodium or potassium hydroxide on aluminum, or displacement from acids by certain metals.
Safety
Hydrogen is highly flammable and also in high enough concentrations may cause asphyxiation and death. For more detail on the hazards associated with hydrogen check the Safety Data sheet.