Chlorine : Methods of Preparation

Chlorine

source : emaze.com

Method of preparation of chlorine :

1. By heating MnO₂ with concentrated hydrochloric acid :

MnO₂ +4HCl ———> MnCl₂ +2H₂O + Cl₂

2. By oxidizing  HCl with KMnO₄: HCl is oxidized to Cl₂.

2KMnO₄ + 16HCl ——–> 2KCl +2MnCl₂+ 8H₂O + 5Cl₂

3. By oxidizing HCl with Potassium dichromate ( K₂Cr₂O_{7) :}

K₂Cr₂O₇ +14 HCl  ———> 2KCl + 2CrCl₃ +7H₂O +3Cl₂

4. By heating a mixture of  NaCl, MnO₂ and Concentrated H₂SO₄ : 

2NaCl +MnO₂ +3H₂SO₄ ——-> 2NaHSO₄ +MnSO₄ + 2H₂O +Cl₂

Manufacture:

1. Deacon’s process:

Principle : HCl is oxidized by air at 450^oC in presence of cupric chloride catalyst.

4HCl + O₂       —–> 2Cl₂ +2H₂O

Mechanism:

2 CuCl₂(Cupric chloride)   ——-> 2CuCl (Cuprous chloride)+ Cl₂

4CuCl +O₂      ——–>     2[CuO.CuCl₂] (Copper oxy chloride)

CuO. CuCl₂ +2HCl  ——–> 2CuCl₂ (Cupric chloride)   +H₂O.

Method:

Mixture of HCl gas and preheated air at 220^o C is introduced in oxidizing chamber. Pumice stones soak in cupric chloride solution are placed on the shelves in oxidizing chamber. Temperature of this chamber is kept 450 degree C. In this chamber HCl gas is oxidized into chlorine.

4HCl +O₂ ———-> 2Cl₂+ 2H₂O

Chlorine obtained is contaminated with HCl gas and water vapour. Gaseous mixture is cooled by cooler and then passed in washing tower. In this chamber, water is sprayed from the top and impurity of HCl is removed. Now the gaseous mixture is passed in absorption tower. Concentrated H2SO4 is sprayed from the top which absorbs water vapour. Mixture of chlorine and air left is collected. Chlorine obtained is impure.

Physical Properties:

1)  It is yellow green gas having pungent  & suffocating smell .

2) Chlorine  is poisonous gas & affect  lungs , nose & throat.

3) It is soluble in H₂O. Aqueous solution of chlorine is called chlorine- water.

4) It acts as  powerful oxidizing agent.

5) It is 2.5 times heavier than air.