Question

The following question is pertaining to the laboratory preparation of hydrogen chloride gas.

Name the drying agent used and justify your choice.

The following question is pertaining to the laboratory preparation of hydrogen chloride gas.

Name the drying agent used in the above preparation and give a reason for the choice.

Answer 1

The drying agent used in the laboratory preparation of hydrochloric acid is conc. sulphuric acid. The other drying agents, such as phosphorus pentoxide (P₂O₅) and quick lime (CaO) cannot be used because they react with hydrogen chloride.

\[\ce{2P2O5 + 3HCl -> POCl3 + 3HPO3}\]

\[\ce{CaO + 2HCl -> POCl3 + 3HPO3}\]