Hydrogen – In a class by itself!

Hydrogen. The most abundant and lightest element in the universe. Essential to life on earth as water. An important component of all organic compounds. Clearly, no matter if its atomic number is 1, hydrogen is certainly no inconsequential lightweight.

It’s true, it accounts for just 0.14% of the earth’s crust by weight, and its low density results in it being present in small quantities in the earth’s atmosphere. But, hydrogen covers almost three-fourths of the earth in the form of water. It is also present in countless carbon compounds in vegetable and animal matter and petroleum, and even accounts for two-thirds of the atoms that make up the human body. Coming back to the universe, hydrogen and helium together account for around 99.9% of all known matter in the universe. Hydrogen is the major component of all stars. During their lifetime, they keep fusing hydrogen into helium as they burn. Interestingly, while helium is classified as an unattractive, noble gas, hydrogen on the other hand is highly reactive, forming bonds with all kinds of elements.

Despite being pro­duced for several de­cades, it took a while for scientists to recognise hy­drogen. In 1671, Robert Boyle noted that gas bub­bles were formed when iron filings reacted with acid. Almost a century later, in 1766, Henry Cavendish first identified hydrogen as an element. He called the gas “inflammable air” and showed that unlike other flammable gases, water was formed when it was burned. In 1783, the French scien­tist Lavoisier gave this gas a name – hydrogène (from the Greek words ‘hydro genes’ meaning water forming), from which we have derived the English name hydrogen.

A look at the periodic table shows that hydrogen does not belong to any family of elements. Although a non-metal, it appears on the left side of the table, above the Group I alkali metal family, to which it clearly does not belong. It occupies a position marking it as the No. 1 element, in a class apart from the rest.

Significance of the discovery of hydrogen

In 1800, Nicholson and Carlisle, followed a few months later by Ritter, succeeded in decomposing water into hydrogen gas and oxygen gas through electrolysis. This led to electrolysis of water being used for the production of hydro­gen gas. The fact that we hardly have any natural hydrogen deposits made the production of hydrogen from abundantly available water assume even greater significance. But electrolysis of water being an energy-intensive process, nowadays hydrogen is mostly produced from fossil fu­els like natural gas.

Listed below are a few of the ways hydrogen has significantly impacted our lives.

Industrial applications

Today around two-thirds of the hydrogen produced in the world is used for manufacturing ammonia. Some other major applications include refining of fuels, pro­duction of fertilizers, nitric acid, and methanol, hydro­genation of unsaturated vegetable and animal oils and fats to make margarine and vegetable shortening, re­ducing aldehydes, fatty acids, and esters to the corre­sponding alcohols, reducing aromatic compounds to the corresponding saturated compounds, reducing ni­tro compounds to amines, reducing iron ores to metal­lic iron, and reducing oxides of tungsten and molybde­num to their metal states.

The aviation connection

Its density being lower than that of air and its ready availability made molecular hydrogen a good lifting gas for balloons and then later in the early twentieth century for the first lighter-than-air airships or zeppe­lins for transporting people by air. With this, the world was introduced to the first form of air travel.

The British airship R34 successfully completed the first non-stop trans-Atlantic flight in 1919. However, the airship Hindenburg bursting into flames mid-air while flying over New Jersey, USA in 1937, put an end to commercial air travel in hydrogen-filled air­ships. Soon, the noble gas helium, having the same lift­ing power as hydrogen, came to be used in airships in America, after which further developments in aviation led to the construction of heavier-than-air aircraft like aeroplanes. And the rest is history.

Rocket fuel

By the 1960s, almost two centu­ries after the first hydrogen inflat­ed balloon was launched, liquid hydrogen came to be used for fill­ing the fuel tanks of NASA rockets. Combustion of hydrogen with ox­ygen or fluorine became the pre­ferred choice for propelling nucle­ar-powered rockets into space.

 The Hydrogen bomb

Unlike the atomic bomb that uses the energy re­leased through the splitting or fission of a heavy atomic nucleus, the hydrogen bomb is a thermonuclear bomb that uses the energy released when two light atoms fuse to form a heavier nucleus. In the H-bomb, two at­oms of either of the two isotopes of hydrogen – deu­terium or tritium – fuse to form a heavier helium nu­cleus. The modern design for the hydrogen bomb was developed in America in 1951. But in 1961, the Soviet Union’s hydro­gen bomb – Tsar Bomba be­came the most powerful nu­clear weapon to be ever test­ed when it was dropped over the Mityushikha

Bay nuclear testing range north of the Arctic Circle. The bomb’s explosive power was so im­mense, its mushroom cloud was around 64 km high. That’s sev­en times the height of Mount Everest. And now North Korea is threatening to detonate one too.

Quantum mechanics

The hydrogen atom H and the hydrogen molecule H2 have the simplest structure possible. And so, they have been used for several decades, ever since the birth of quantum mechanics, as the ideal prototype of an atom and molecule respec­tively for critically evaluating various quantum me­chanical models.

Further advances by the first element

From the days when NASA first used hydrogen-ox­ygen fuel cells for firing space capsules and satellites, fuel cells have seen many more applications and un­dergone further development. One of them was the successfully created early form of the rechargeable bat­tery in the 1970s based on electrochemical storage of hydrogen in the form of a metal hydride, resulting in the introduction of nickel – metal hydride batteries for powering vehicles. This in turn led to a renewed inter­est in electric vehicles by almost all the major automo­bile manufacturers.

Also, since the last few decades, scientists and oth­er experts have been discussing ‘the hydrogen econo­my’ that could lead to hydrogen possibly replacing pe­troleum-based fuels. Hydrogen’s probable role in the future as a primary energy carrier for various purpos­es including transportation would certainly have sig­nificant advantages. For one, since hydrogen fuel cells generate electricity and water, they would produce ze­ro pollutants. Secondly, hydro­gen can be produced from mul­tiple sources such as natural gas, oil, other fossil sources, and through electrolysis of water. Hence, the possibility of feed­stock shortages too could be mi­nimised. However, there are a few hurdles to be overcome be­fore the general public can use hydrogen technologies safely and conveniently. For instance, hydrogen being highly flam­mable, safer systems for storing and transporting it would need to be developed. Currently, the industrial production of hydrogen from methane re­leases CO2 into the air. A way out would be develop­ing low-cost methods for splitting water using renew­able electrical resources like solar energy and wind as a clean way of mass producing hydrogen economically.

With even further advances in the applications of hydrogen, it perhaps won’t be too long before what Jules Verne had written in his novel The Mysterious Island way back in 1874 becomes a reality. One of Verne’s characters says, “I believe that water will one day be employed as fuel, that hydrogen and oxygen … will furnish an inexhaustible source of heat and light …” Prophetic words perhaps.

References

  1. Wojciech Grochala: First there was hydrogen – Nature Chemistry, 7, 264, 20 February, 2015
  2. Judith Klinman: Hydrogen – C&EN, Vol 81, Number 36, September 08, 2003
  3. Renewable Energy World: Hydrogen Energy – http://www. renewableenergyworld.com
  4. Science Learning Hub: Hydrogen – the number 1 element, https://www.sciencelearn.org.nz, 28 October 2009
  5. Laura Geggel: Why is hydrogen the most common element in the universe?- www.livescience.com, April 1, 2017
  6. Agata Blaszczak-Boxe: Facts about hydrogen – www.li­vescience.com, January 23, 2015
  7. Ashwin Kumar: Hydrogen Economy – A Future Where Hydrogen Is The Energy Currency, www.techstory.in, December 22, 2016
  8. www.sciencedaily.com : Low cost, scalable water split­ting fuels the future hydrogen economy, Source: Penn State Materials Research Institute, May 31, 2017
  9.     9. Mitch Jacoby: Moving toward a hydrogen economy – C&EN, Vol 81, Number 23, June 9, 2003

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