Chemistry - Hydrogen

Introduction

• In the periodic table, hydrogen is the lightest element, its atomic weight is merely 1.008.

• The symbol of hydrogen is ‘H’ and the atomic number is ‘1.’

• In the early 16^th century, hydrogen gas was first artificially produced by the reaction of acids and metals.

• Henry Cavendish first recognized the hydrogen gas a discrete substance during the period of 1766-81, as it produces water when it is burned.

Salient Features of Hydrogen

• In their plasma state, the non-remnant stars are primarily composed of hydrogen.

• At standard temperature and pressure, hydrogen appears colorless, tasteless, odorless, nonmetallic, non-toxic, and highly combustible diatomic gas.

• The molecular formula of hydrogen is H₂.

• On the earth, hydrogen exists in molecular forms, for example, water or other organic compounds.

• Hydrogen also plays an important role in acid–base reactions.

• Hydrogen gas is highly flammable in the air.

• Pure hydrogen-oxygen flames radiate ultraviolet light; further, with high oxygen mix are nearly invisible to the naked eye.

• Hydrogen can react with almost every oxidizing element.

• At room temperature, Hydrogen normally reacts spontaneously and viciously with chlorine and fluorine and forms the corresponding hydrogen halides.

Occurrence of Hydrogen

• Consisting roughly about 75 percent of all baryonic mass, hydrogen is the most abundantly found chemical subsistence in the universe.

• Throughout the universe, hydrogen is typically found in the atomic and plasma states; however, the properties quite different from those of the molecular hydrogen.

• On the earth, hydrogen exists as the diatomic gas, i.e. H₂.

• Because of having light weight, hydrogen easily escapes from the earth’s atmosphere.

• Hydrogen is the third most abundant element found on the Earth's surface, but largely found in form of hydrocarbons and water.

Compounds of Hydrogen

• Following are the major compounds of hydrogen −

  • Water - H₂O

  • Ammonia - NH₃

  • Hydrogen chloride - HCl

  • Hydrogen fluoride - HF

  • Hydrogen sulfide - H₂S

  • Methane - CH₄

  • Hydroxide - OH^-

  • Hydrogen bromide - HBr

  • Hydrogen iodide - HI

  • Hydrogen cyanide - HCN

  • Phosphine - PH₃

  • Hydrogen selenide - H₂Se

  • Methanol - CH₃OH

  • Lithium hydride - LiH

  • Bicarbonate - HCO₃

  • Hydrogen telluride - H₂Te

  • Liquid hydrogen - H₂

  • Cyanide - CN

  • Calcium hydride - CaH₂

  • Heavy water - D₂O

  • Diborane - B₂H₆

  • Sodium hydride - NaH

  • Potassium hydride - KH

Uses of Hydrogen

• The largest amount of H₂ is used in the processing of fossil fuels as well as in the production of ammonia.

• Hydrogen (H₂) is extensively used in the petroleum and chemical industries.

• H₂ is typically used as a hydrogenating agent, especially in increasing the saturation level of unsaturated fats and oils.

• H₂ is also used as a shielding gas in welding procedures, such as atomic hydrogen welding, etc.