Chemical Reactions of Hydrogen

Hydrogen is made up of one electron and one proton. It is one of the significant components of water (H20) and all the other organic substances present on the Earth. Saturn and Jupiter are made up of hydrogen, which shows that this gas is spread out. Like other alkali metals, it contains one electron in its valence shell and produces the monovalent ion H+, but it resembles halogens in ionisation energy. Hydrogen has a single positively charged proton, single negatively charged electron, and one, two, or three neutrons in its nucleus.

Isotopes are distinct versions of the same element with varying neutron counts. The mass of the hydrogen ion is affected by the number of neutrons that exist in it. Hydrogen is an odourless, tasteless, colourless, non-poisonous gas consisting of a diatomic molecule H2. Since hydrogen readily forms covalent compounds with many nonmetallic elements, most hydrogen found on Earth is in molecular forms, like water or organic molecules.

Chemical Structure of Hydrogen

Hydrogen atoms consist of one positive charge proton and one negative charge electron, and one (1), two (2) or three (3) neutrons in the nucleus of hydrogen. The atomic mass of a hydrogen atom is determined by the number of neutrons present in the nucleus. The isotopes of hydrogen are not to be confused with the allotropes of hydrogen.

Preparation of Hydrogen

Breaking chemical bonds is required to produce elemental hydrogen from molecules. The following are the most popular hydrogen preparation methods:-

• The chemical reaction of hydrogen
• The reaction of ionic metal hydrides with water
• Electrolysis
• Reaction with metals and acids
• From steam and carbon or hydrocarbons

Hydrogen is chemically inactive under normal conditions; it participates in various chemical processes through the heating process.

The synthesis of ammonia, a fertiliser utilised to produce nitric acid, consumes two-thirds of the world’s hydrogen. Large amounts of hydrogens were required in the hydrogenation process, covered in the organic chemistry chapter.

Hydrogen is a non-polluting fuel that can be used. The interaction between hydrogen and oxygen is highly exothermic, producing 286 kiloJoule of the energy/mole of H2O. Under a controlled situation, hydrogen burns without exploding. Due to the enormous heat of hydrogen combustion, the oxygen-hydrogen torch can reach temperatures of around 2800 °C. This torch’s intense flame is ideal for cutting heavy sheets of metal.

Reactions of Hydrogen with Elements

Hydrogen reacts with group 1 metals and Sr, Ba, and Ca when it is heated. In general, hydrogen reactions with nonmetals result in acidic hydrogen molecules containing hydrogen in a state of 1+ oxidation. As electronegativity of nonmetals grows, the reactions convert to highly volatile and exothermic. When heated, hydrogen reacts solely with sulphur and nitrogen, but it combines vigorously with fluorine (producing HF) and, in some cases, chlorine (producing HCl).

If the mixture of oxygen and hydrogen is ignited, it will explode. Due to the unstable nature of the reaction, attention should be exercised while dealing with hydrogen in confined spaces to reduce the production of explosive mixture. Although most nonmetal hydrides are acidic, ammonia and phosphine (PH3) are extremely weak acids used as bases.

Reaction of Hydrogen with Compounds

Many metals’ heated oxides are reduced by hydrogen, resulting in the creation of water and metal vapour. Passing H gas over hot CuO, for example, produces water and copper. Hydrogen can also lower the oxidation state of metal oxides:

H₂(g) + MnO₂(s) → ΔMnO(s) + H₂O(g)

Reaction with active metal and water

2 Na(s) +2 H₂O(l)  →2  Na+(aq)+2 OH-(aq)+H₂(g)

Reaction with ionic metal hydride and water

NaH(s) +H₂O(l)→ Na+(aq)+OH-(aq)+H₂(g)

Uses of Hydrogen

• Hydrogen is utilised in the making of nitrogenous fertilisers.
• Hydrogenating unsaturated vegetable oils make vanaspati fat.
• Hydrogen is utilised in the formation of various organic chemicals, like methanol.
• Hydrogen is a crucial compound in the formation of hydrogen chloride.
• Several metal oxides in metallurgical processes use hydrogen for making metals.
• It is used as rocket fuel in space research centres.