Preparation of Hydrogen


Great care should be ensured before preparing and collecting the hydrogen gas. It should be kept in mind that the removal of air from the apparatus is a foremost important step as the mixture of hydrogen with the air is highly explosive.

How Granulated Zinc is Used to Make Hydrogen

In the laboratory, hydrogen gas is prepared by the action of diluted hydrochloric acid or dilute sulphuric acid on the granulated zinc. In the granulated zinc, an impurity like the copper is present which acts as a positive catalyst. The general feature of a positive catalyst is to increase the rate of a chemical reaction. So, due to this reason, pure zinc is not preferred but granulated zinc is used to prepare hydrogen gas in the laboratory. The hydrogen gas which is produced by this reaction is collected by the downward displacement of the water.

Preparation of Hydrogen by Electrolysis of Water

The electrolysis of water is used to prepare the dihydrogen of high purity. The electrolysis of water is done in the small amount of a base or an acid. During this process dihydrogen is collected at the cathode and oxygen is liberated at the anode. Pure water is weakly ionized and it is the poor conductor of the electricity, but due to the presence of a base or acid, it conducts electricity in a better way. This method is quite expensive and is not used commercially.

Preparation of Hydrogen from Alkalis and Acids

Some metals such as Sn, Zn, and Be reacts with the boiling alkali solution and liberates dihydrogen. While on the other hand the metals which are more electropositive than the hydrogen such as Mn, Fe, and Zn reacts with the diluted mineral acids and liberate the dihydrogen gas. Some other metals like Ag, Hg, and Cu, which are less electropositive than the hydrogen does not liberate the hydrogen from the acids.

Preparation of Hydrogen from Hydrocarbons

Hydrogen gas can be prepared by partial oxidation of the hydrocarbons. A mixture of hydrocarbons is mixed with the steam and it is passed over the heated Nickel catalyst at a temperature of 1270K. In this process, natural gas can also be used and the whole process of obtaining the dihydrogen gas from the natural gas is also called as the steam reforming process. Thermal cracking of natural gas can also be used to produce dihydrogen.

Preparation of Hydrogen from the Syngas- Bosh Process

A mixture of dihydrogen and carbon monoxide is produced when the superheated steam is passed over the red-hot coke or coal at the temperature of 1270K in presence of Nickel catalyst. However, the removal of carbon monoxide is a difficult process.

Preparation of pure Dihydrogen Gas

Pure dihydrogen gas can be prepared in the following ways.

  • By the action of pure sulphuric acid on the magnesium ribbon.
  • By the electrolysis of the warm solution of barium hydroxide by using Nickel or Platinum electrodes.
  • By the action of water on the sodium hydride.
  • By the action of potassium hydroxide on the scrap aluminum.


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