Question

How will you prepare chlorine in the laboratory?

Answer 1

1. Chlorine is prepared by the action of cone, sulphuric acid on chlorides in presence of manganese dioxide.

\[\ce{4NaCl + MnO2 + 4H2SO4 -> Cl2 + MnCl2 + 4NaHSO4 + 2H2O}\]

2. It can also be prepared by oxidising hydrochloric acid using various oxidising agents such as manganese dioxide, lead dioxide, potassium permanganate or dichromate.

\[\ce{PbO2 + 4HCl -> PbCl2 + 2H2O + Cl2}\]

\[\ce{MnO2 + 4HCl -> MnCl2 + 2H2O + Cl2}\]

\[\ce{2KMnO4 + 16HCl -> 2KCl + 2MnCl + 8H2O + 5Cl2}\]

\[\ce{K2Cr2O7 + 14HCl -> 2KCl + 2CrCl3 + 7H2O + 3Cl2}\]

3. When bleaching powder is treated with mineral acids chlorine is liberated.

\[\ce{CaOCl2 + 2HCl -> CaCl2 + H2O + Cl2}\]

\[\ce{CaOCl2 + H2SO4 -> CaSO4 + H2O + Cl2}\]