Question

Draw a labelled diagram and explain the laboratory preparation of hydrogen chioride gas.

Answer 1

Hydrogen chloride gas is prepared by the reaction of sodium chloride and sulphuric acid at the temperature below 200°C. Sodium chloride is preferred for laboratory preparation of HCI gas since it is cheapest and most easily available chloride. Lower temperature is preffered because at higher temperature sodium sulphate forms a hard crust and sticks to the bottom of the flask and is difficult to remove.
\[\ce{\underset{\text{Sodium chloride}}{NaCl} + \underset{\text{Sulphuric acid(conc.)}}{H2SO4} ->[<200°C] NaHSO4 + \underset{\text{Hydrogen chloride gas}}{HCl}}\]