Question

The following questions are pertaining to the laboratory preparation of Hydrogen chloride gas.

Name the drying agent used and justify your choice.

Answer 1

• Hydrogen chloride($\mathbf{HCl}$) formed in the laboratory contains moisture.
• Drying agents are used to make a gas pure that is to make it free from water.
• For Hydrogen chloride($\mathbf{HCl}$) gas the drying agent that can be used for removing water is Sulphuric acid (${\mathbf{H}}_{\mathbf{2}}{\mathbf{SO}}_{\mathbf{4}}$).
• Since Sulphuric acid is a powerful dehydrating agent, it will easily remove the water content from Hydrogen chloride gas.
• Other drying agents such as Calcium oxide ($\mathbf{CaO}$) and Phosphorus pentoxide (${\mathbf{P}}_{\mathbf{2}}{\mathbf{O}}_{\mathbf{5}}$) react with Hydrogen chloride gas. Therefore, they are not used as drying agent.
• Therefore, Sulphuric acid is the drying agent used in dry Hydrogen chloride.