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Hydrogen Formula – Structure, Properties, Uses, Sample Questions

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The most abundant chemical element in the universe is Hydrogen. It is the first element in the periodic table with the symbol H and atomic number 1. Hydrogen in its molecular state is a diatomic molecule, H2. Hydrogen is the lightest element found on earth, and it is colorless, odorless, and tasteless. Of the entire Hydrogen present on Earth, most of it is present in the form of water and organic compounds.

Hydrogen Formula

The molecular formula of hydrogen is H2. The bonding between two hydrogen atoms is a covalent bond. Each hydrogen molecule has one valence electron in its valence shell. Thus, two hydrogen atoms collectively share an electron and form a single covalent bond.

Structure of Hydrogen Gas

 

Production of Hydrogen

Hydrogen is obtained as a byproduct of many reactions taking place in chemistry and biology labs, but on a large scale, Hydrogen gas is prepared by the hydrogenation of unsaturated substrates. A few methods of hydrogen production are listed below:

  • Methane pyrolysis

Pyrolysis is the process of splitting hydrocarbons into their elemental compounds, i.e., Hydrogen and Carbon. Similarly, pyrolysis of methane under the presence of catalyst(Nickel) produces Hydrogen gas and Carbon. The reaction involved is as follows:

CH4(g) → C(s) + 2H2(g)

In the above reaction, one molecule of Methane breaks into one molecule of solid Carbon and 2 molecules of Hydrogen gas.

  • Water Electrolysis

Electrolysis of water is one of the best methods employed to produce Hydrogen gas. During this process, gaseous Oxygen is formed at the anode, and hydrogen gas is formed at the cathode. The reaction involved is as follows:

2 H2O(l) → 2 H2(g) + O2(g)

In the above reaction, two molecules of Water breaks into two molecules of Hydrogen gas and 1 molecule of  Oxygen gas.

Physical properties of Hydrogen

  • Hydrogen gas is a diatomic molecule.
  • Hydrogen gas is colorless, odorless, and tasteless.
  • The molar mass of Hydrogen gas is 2.016 g/mol.
  • The boiling point of Hydrogen gas is -252.9°C.
  • The melting point of Hydrogen gas is -259.2°C.

Chemical properties of Hydrogen

  • Hydrogen gas is highly reactive and flammable at high temperatures. The reaction involved is as follows:

2 H2(g) + O2(g) → 2 H2O(l) 

  • Hydrogen gas reacts with halogens to form acids.

H2 + Cl2 → 2HCl

Hydrogen gas reacts with disulphur to form hydrogen sulfide. The reaction involved is as follows,

H2 + S2  → 2H2S

Uses of Hydrogen Gas

  • Hydrogen is used as a good reducing agent. It reduces aldehydes and esters to corresponding alcohols.
  • Hydrogen gas can be used as rocket fuel.
  • It is also used to reduce iron ores to metallic iron.
  • Hydrogen gas is used as a lifting gas in balloons.
  • Hydrogen gas is used in atomic hydrogen welding.

Sample Questions

Question 1: List the important isotopes of Hydrogen.

Answer:

There are three naturally occurring isotopes of Hydrogen namely, protium (1H), deuterium (2H), and tritium (3H).

  • Protium: It consists of one proton and one electron.
  • Deuterium: It consists of one proton, one neutron, and one electron.
  • Tritium: It consists of one proton, two neutrons, and one electron.

Question 2: Describe the bonding and atomic nature of hydrogen.

Answer:

Hydrogen is made of a single proton and one electron, and no neutrons. Hydrogen can impart its solitary electron to different molecules, and subsequently, it can frame a bond with other reactive atoms.

Question 3: Write about the two molecular forms of hydrogen.

Answer:

There are two types of molecular hydrogen. They are para-hydrogen and ortho-hydrogen.

Ortho-hydrogen: In a hydrogen molecule if the spin of both the nuclei is in the same direction then it’s called ortho-hydrogen.

Para-hydrogen: In a hydrogen molecule if the spin of both the nuclei is in the same direction then it’s called ortho-hydrogen.

Question 4: Write the reaction involved in the production of Hydrogen gas by Serpentinization reaction.

Answer:

In the process of serpentinization,  H+ ions are reduced by ferrous (Fe+2) ions from fayalite (Fe2SiO4). The reaction forms magnetite, quartz, and hydrogen gas.

3Fe2SiO4 + 2 H2O → 2 Fe3O4 + 3 SiO2 + 3 H2

Question 5: List a few health hazards caused due to Hydrogen gas.

Answer:

  • If the presence of hydrogen gas is very high, then the availability of oxygen is very less, which causes difficulty in inhalation.
  • Inhalation of hydrogen gas leads to headache, dizziness, nausea, and vomiting.

Question 6: What happens when hydrogen gas reacts with metal oxides at high temperatures and pressure?

Answer:

Hydrogen gas reacts with metal oxides at high temperatures and pressure and reduces the metal oxides into corresponding metals. One such reaction is as follows:

H2 + FeO → Fe + H2O

In the above reaction, when one molecule Hydrogen reacts with one molecule Ferric Oxide then it produces one molecule of Iron and 1 molecule of Water.

Question 7: Explain the reaction between hydrogen gas and palladium chloride.

Answer:

Hydrogen gas reacts with palladium chloride and reduces it to palladium metal. Hydrochloric acid is obtained as a byproduct of this reaction. The reaction involved is as follows:

 H2 + PdCl2 → Pd + 2HCl

In the above reaction, when one molecule Hydrogen reacts with one molecule palladium chloride then it produces one molecule of palladium and 2 molecules of Hydrochloric acid.



Last Updated : 20 Dec, 2023
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