Chemical formula: H₂. 

A molecule of hydrogen gas consists of two atoms of hydrogen that are chemically bonded together.

Physical properties

Appearance: Colorless and odorless, tasteless gas, at room temperature.

Density: It has a very low density; at STP, it is approximately 0.08988 g/L.

Solubility: Sparingly soluble in water but more soluble in organic solvents

Flammability: Extremely flammable. It forms explosive mixtures with air.

Boiling Point: -252.9 °C (-423.2 °F).

Melting Point: -259.2 °C (-434.6 °F).

Molecular Weight: Approximately 2.016 g/mol.

Chemical properties

Combustion:

Hydrogen catches fire in the presence of oxygen and yields water

Energy liberated is quite high, around 286 kJ/mol and is exothermic

The product can be gaseous and liquid, depending upon temperature and pressure

Reactivity:

It combines with nonmetals

With Oxygen: It yields water. It is explosive in nature, if it gets ignited by any spark or flame under conditions.

With Halogens: Hydrogen combines with halogens like chlorine and bromine to produce hydrogen halides, HCl and HBr. These are highly strong acids in aqueous solution.

Reducing Agent: Hydrogen is a reducing agent in many reactions. Hydrogen can reduce the metal oxides into their respective metals.

where M is a metal and MO is its oxide. This property is crucial in many metallurgical processes.

Acid-Base Behavior:

Hydrogen acts as a weak acid by donating protons (H⁺) in reactions with strong bases. It can combine with water to form hydronium ions (H₃O⁺) in the following process.

Formation of Acids:

Hydrogen reacts with electronegative elements, resulting in the formation of acids. Here are some examples of acids formed by hydrogen:

Hydrogen Chloride (HCl)

Hydrogen Sulfide (H₂S): In addition, hydrogen can react with sulfur to form a very toxic gas called hydrogen sulfide.

Formation of Complexes:

Hydrogen can form hydrides, which is the ability to combine with metals, change their properties and reactivity.

Application

Fuel Cells: Converts fuel into electricity with water as the only byproduct.

Direct Fuel: Used in compression ignition of combustion engines and turbines.

Production of Ammonia: Comprises Haber process for fertilizers.

Hydrogenation: Hydrates unsaturated fats by converting them to saturated fats.

Reducing Agent: Converts metal ores into pure metals by reducing them.

Heat Treatment: Deoxidizes a metal during the processing stage.

Removal of Oxides: Prevents oxides during semiconductor manufacturing.

Fats and Oils: Hydrogenerates oils to enhance shelf life.

Reducing Atmosphere: Prevents oxidation during the glass-making process.

Rocket Fuel: Propellant in space vehicle

Medicines:Active pharmaceutical ingredients 

Energy Storage: Renewable energy storage

Waste Treatment: Effluent wastewater decontamination.

Conclusion

Hydrogen will find widespread application in many industries as a clean-burning fuel, of great promise for future use, particularly in sustainable energy source applications and carbon reduction. Its role will become that much more prominent as technology advances.

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