Liquid hydrogen has a density of 70 kg/m3. Gaseous hydrogen at standard atmospheric pressure and temperature has a density of 0,089 kg/m3.
The metabolism of human beings, animals and microbes depends on water, composed of hydrogen and oxygen. The human body contains about 70% water. Human beings need about 2 liters water per day for drinking, hard working people need even more.
- Hydrogen may be used directly as a fuel for a propulsion system, or, through the sabatier reaction, in the form of methane for the same purpose.
- Hydrogen can be used to react with iron ore or aluminium ore to create metals and water.
- Hydrogen can be combined with carbon to create carbohydrates, amino acids and hydrocarbons, the building blocks all all living organisms.