Dihydrogen

What is Dihydrogen?

Dihydrogen is the homonuclear diatomic molecule formed from two hydrogen atoms. This molecule features a covalent bond between two hydrogen atoms, satisfying each of their required duet configurations. Since hydrogen is the lightest element on the modern periodic table, dihydrogen is the lightest known molecule. Since the standard atomic weight of the hydrogen atom is 1.008u, the molecular weight of the dihydrogen molecule is 2.016 atomic mass units.

Under standard conditions for temperature and pressure (often abbreviated to STP), dihydrogen exists as a colourless, tasteless, and odourless gas which is highly combustible in nature. The molecular formula of dihydrogen is H2.

Structure of Dihydrogen

The dihydrogen molecule features a single covalent bond between the two hydrogen atoms that constitute it. This molecule has a linear shape and is nonpolar in nature. Each hydrogen atom contributes one electron towards the covalent bond. Therefore, the duet configuration requirements of both the hydrogen atoms that constitute the dihydrogen molecule are satisfied.

Properties of Dihydrogen

  • At STP, dihydrogen exists in the gaseous state.
  • The melting point of H2 is 13.99 Kelvin. Converting this value to the celsius scale, the melting point of dihydrogen can be represented as -259.16 degrees celsius.
  • The boiling point associated with dihydrogen corresponds to 20.271 on the Kelvins scale. Converting this value into the celsius scale, the boiling point of H2 can be expressed as -252.879 degrees celsius.
  • The latent heat of fusion associated with the H2 molecule corresponds to 0.117 kilojoules per mole.
  • The latent heat of vaporization (also known as the enthalpy of vaporization) of dihydrogen is equal to 0.904 kilojoules per mole.
  • The molar heat capacity of H2 is roughly equal to 28.83 joules per mole Kelvin.
  • The speed of sound when it propagates through gaseous H2 is 1310 meters per second.

Applications of Dihydrogen

In the chemical industry and the petroleum industry, large quantities of H2 are required on a regular basis. Dihydrogen’s main use is in the refining of certain fossil fuels and also in ammonia manufacturing. The petrochemical industry is one of the main consumers of H2. This industry utilizes dihydrogen for processes like hydrodesulfurization, hydrodealkylation, and also hydrocracking. Dihydrogen has many other important applications. For example, this compound can be used as a hydrogenating agent, especially in order to increase the saturation level of unsaturated fats and oils (which are usually found in products like margarine). This compound is also used in methanol development. Similarly, dihydrogen serves as the source of hydrogen in hydrochloric acid production. H2 also acts as a reducing agent and can, therefore, be used to treat metallic ores.

Biochemistry of Dihydrogen

It is not uncommon for dihydrogen to be formed as a result of certain forms of anaerobic metabolism. This compound is also formed by many microorganisms, generally via chemical reactions that are catalyzed by enzymes. These enzymes which catalyze biochemical reactions involving the release of dihydrogen are known as hydrogenases, and are known to contain iron or nickel.

Hydrogenases are known to catalyze the reversible redox reaction of two protons and two electrons (reactant side) and molecular dihydrogen (product side). The creation of hydrogen gas occurs when reducing equivalents (which are formed during pyruvate fermentation) are transferred to water. It can be noted that the natural cycle of the production and consumption of hydrogen through different phases of the ecosystem is called the hydrogen cycle.

Hazards Associated with Dihydrogen

Dihydrogen reacts with almost all elements that behave as oxidizing agents or have any amount of oxidizing power. H2 has the ability to react with halogens like chlorine and fluorine in a very spontaneous and violent manner, even at reaction temperatures as low as room temperature. The products formed from these violent reactions include halides of hydrogen such as hydrogen chloride and hydrogen fluoride, both of which are also potentially harmful acids.

To learn more about the properties and applications of dihydrogen along with its biochemistry and biochemical role in human metabolism, register with BYJU’S and download the mobile application on your smartphone.

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