STD VIII – HYDROGEN (Online)

Introduction to Hydrogen

Hydrogen is the main fuel of stars and the only fuel for red dwarfs.

Hydrogen does not exist in a pure form on earth but is mostly found as part of water.

We will study the occurrence and various methods of preparing hydrogen.

 Preparation of Hydrogen

Hydrogen is produced when the acidified water is electrolyzed by using the platinum electrodes. To obtain high purity hydrogen, we can electrolyze the warm aqueous barium hydroxide solution between the nickel electrodes.

Lab preparation of hydrogen

Collection of hydrogen is by downward displacement of water as it is sparingly soluble in water. Granulated zinc is used because it contains copper as an impurity. Copper acts as a catalyst in the reaction

Tests for Hydrogen:

Ordinary hydrogen burns in air with a characteristic pop sound.

Hydrogen burns in air or oxygen with a pale blue flame and water is formed.

Redox Reactions – Both oxidation and reduction takes place simultaneously.

Oxidation Reaction – Removal of hydrogen and addition of oxygen. Reduction Reaction – Removal of oxygen and addition of oxygen