Question
How HCl is prepared on a large scale from NaCl?
Answer
An early process to manufacture hydrochloric acid by distilling a mixture of Nacl and concentration H2SO4 at 500oC in a cast iron vessel, provided with delivery tubes. The evolved HCl vapour is absorbed in a series of glazed earthen receivers containing water. This acid contaminated with carried-over H2SO4 is removed by distilling over a mixture of BaCl2 and copper turnings.
2NaCl (s) + H2SO4 (l) → Na2SO4 (s) + 2HCl (g)