Hydrogen chloride gas is prepared in the laboratory by the action of concentrated sulphuric acid on sodium chloride.
(a) Give balanced chemical equation for the above reaction.
(b) State the method of collection of the gas formed above.
(c) What is the property of sulphuric acid that makes it a suitable reagent for the reaction?
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(a) NaCl + H2SO4 $\xrightarrow{\text{\textless 200°C}}$ NaHSO4 + HCl↑
(b) HCl gas formed is collected by upward displacement of air method.
(c) As conc. H2SO4 is non-volatile and has a high boiling point, therefore, it displaces the volatile hydrogen chloride from the salt sodium chloride. Hence, conc. H2SO4 is used as a reactant in the laboratory preparation of HCl from sodium chloride.
Conc. nitric acid cannot be used in place of conc. H2SO4 since it is volatile and may volatize out along with the hydrogen chloride.