Hydrogen

Hydrogen was discovered by Henry Cavendish in 1766. The name is derived from the Greek ‘hydro’ and ‘genes’ meaning water forming. In 1783, Antoine Lavoisier first obtained hydrogen from water and recognized that water is the compound of hydrogen and oxygen.

Hydrogen

Hydrogen, denoted by H and has chemical formula H2 is the very simplest chemical element. Its atomic number is 1 and its atomic weight 1.00797 g/mol. Hydrogen has only one electron in its orbital which is the member of s-block elements.

Hydrogen is the lightest element of the earth. It is odourless, colourless, tasteless, non-toxic, and a highly combustible element. The hydrogen atom is formed by a nucleus with a unit positive charge and one electron. Hydrogen has a +1, -1 oxidation state. It has a density of 0.00008988 grams per cubic centimetre. It has a melting point of 13.81 K (-259.34°C or -434.81°F) and boiling point is 20.28 K (-252.87°C or -423.17°F). 

Nearly 90% of the visible universe is composed of hydrogen. Hydrogen is the most abundant of all elements in the universe. Hydrogen could not occur in free state and form diatomic molecules (H₂) by the covalent bonding. Therefore, the nature of molecular hydrogen is diatomic and covalent. 

Isotopes of hydrogen

There are three hydrogen isotopes which is protium, mass 1, found in something about 99,985% of the natural element; deuterium, mass 2, found in nature something about 0.015%, and tritium, mass 3, which appears in small quantities in nature but can also be artificially produced by various nuclear reactions.

1. Protium or Simple hydrogen: It is the most abundant isotope of hydrogen. Nucleus of a protium contains only one nucleus, it does not contain a neutron. Atomic number of protium is 1 and the electronic configuration is 1s¹. Extent of protium in hydrogen found

in nature is 99.99%. It is represented as 12H or 11P.

2. Deuterium or Heavy hydrogen : It is present in heavy water (D₂O). It is obtained by the electrolysis of heavy water. Its atomic number is 1 and mass number is 2. Its nucleus contains one proton and one neutron. The extent of it in naturally occurring hydrogen is 0-016%. It is represented by 21H. 

3. Tritium or Radioactive hydrogen : It is not stable due to its radioactivity. Tritium emits low energy B-particles. Its half life period is 12.33 year. Nucleus of tritium contains one proton and two neutrons. Its atomic number is 1 and mass number is 3. Its abundance in nature is 1×10-17. Thus, it is a very rare isotope. It is represented by 31H. 

Formation of hydrogen:
Hydrogen is an organic and commercially important element. To form ammonia large amounts of hydrogen are combined with nitrogen from the air to produce ammonia (NH3) through a process called the Haber process. 

Ammonia is produced by heating nitrogen (1 volume) and hydrogen (3 volume) at 450°-500°C, under a high pressure of 200-800 atmosphere in the presence of ferric oxide (Fe₂O3) as a catalyst and molybdenum as promoter. 

                         N₂ + 3H₂ ——->2NH3 +92-4 KJ mol-¹ 

Nitrogen obtained from liquid air is mixed with three times hydrogen and compressed at pressure of 200-800 atmosphere. The compressed air is passed through a chamber containing Fe2O3 as catalyst and molybdenum powder as promoter at supset 450-500⁰C. The gas coming out of the chamber contains 15-40% ammonia. The gases are passed through a condenser where only ammonia liquefies. The uncondensed mixture of N2 and H₂ is pumped to the compressor from where it is sent to the catalytic chamber again. 

Hydrogen is also added to fats and oils, such as peanut oil, through a process called hydrogenation.

Hydrogen as a fuel: Advantages

Nowadays Efforts are being made to obtain an alternative fuel. Hydrogen in the liquid form is probably the best solution since a large amount of energy is released by the combustion of hydrogen. Dihydrogen has been proposed as a fuel for other optional energy sources. Some advantages are as follows in the form of fuels.  

1. It is abundantly available as the form of water in their combined state.

2. Its use as fuel is pollution free because it forms only water on combustion. 

3. The calorific value of heat arises from the combustion of hydrogen more than the other fuel.

4. Efficiency of the combustion engine for hydrogen is 25 to 50% greater than that of petrol. 

5. Hydrogen-oxygen fuel cells can be easily used for driving motor vehicles. 

6. Hydrogen is a good reducing agent. It is used instead of coal and is pollution free. 

7. Regeneration of it from water is more convenient and less time consuming. 

Obstacles in the use of hydrogen as a fuel

However, hydrogen is indicated as the fuel for future references but its use is not so convenient. It has some behavioural difficulties which are as follows:

1. Availability of Hydrogen: Hydrogen is available in free state. Thus, for the production of fuel its economical production is essential. For the production of hydrogen from water, nuclear energy and solar energy needs to be used. 

2. Storage and transportation: Hydrogen is combustible in nature. Thus, its storage and transportation from one place to another place is difficult. For the storage, three times greater tank than the petrol tank will be required. 

Conclusion

For years researchers have been experimenting with hydrogen with great interest because of its potential as an environmentally friendly fuel. “Hydrogen is a carbon-free ingredient, so when you burn it you produce only water,” making it pure, non-exhaust gas. The major problem with Hydrogen gas is it is more expensive than the others.