STD IX – STUDY OF FIRST ELEMENT – HYDROGEN – (Online)

Position of the non-metal (Hydrogen) in the periodic table

Hydrogen, H2, is the simplest element. It is the first element in the periodic table, and it is placed in Group I of the periodic table.

Some previous attempts have been made to classify hydrogen as Group 1 (Alkali metal) or as group 7 (halogen), but neither were satisfactory.

Hydrogen is the lightest element and the most abundant element in the universe.Its atom consists of just a proton and an orbiting electron.

Without hydrogen we would not be here; all organic compounds making up living things contain hydrogen and it is also a constituent of water, necessary for all known life.

Hydrogen is therefore arguably the most important element for life.

Lab Preparation of Hydrogen

Since hydrogen gas is almost insoluble in water, it can be collected by displacement of water. It is not collected by downward displacement of air because it forms an explosive mixture with air.

Impurities and their removal

Hydrocarbons are the major source for the production of hydrogen gas, by, for instance, reforming of fossil fuel, natural gas, or biomass. However, the hydrogen produced by this process is not pure, but a mixture of gases known as reformate.

Manufacture of hydrogen by Bosch process

Bosch process:

In this method, water gas is mixed with twice its volume of steam and passed over heated catalyst Fe2O3 in the presence of a promoter Cr2O3 at 773 K when CO2 and H2 are obtained.

Manufacture of Hydrogen from water [ Electrolysis]

Commercially hydrogen is obtained by the “electrolysis” of acidulated water.

A small amount of ulphuric acid (H2SO4) is added to water because pure water being a poor conductor of electricity, and adding a less volatile acid makes it a conductor.

Electric current is passed through this acidulated water and the water dissociates.

Test for Hydrogen

Hydrogen is combustible but does not support combustion. A hydrogen–air mixture burns with a characteristic ‘pop’ sound. Pure hydrogen burns silently in the air with a pale blue flame.

Using a flame is the best method of testing for the presence of hydrogen. When using the flame test, hydrogen comes into contact with oxygen, creating hydrogen oxide. This process is called oxidation.