Question

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

Name the drying agent used and justify your 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 quicklime (CaO) cannot be used because they react with hydrogen chloride.

2P₂O₅ + 3HCl → POCl₃ + 3HPO₃

CaO + 2HCl → POCl₃ + 3HPO₃