Question

Question 8.23 Chlorine is used to purify drinking water. Excess of chlorine is harmful. The excess of chlorine is removed by treating with sulphur dioxide. Present a balanced equation for this redox change taking place in water.

Class XI Redox Reactions Page 274

Answer 1

                 O.N increases from +4 to +6
                 |---------------------------------------|
0             +4                              -1          +6
Cl₂    +     SO₄   +  H₂O--------> Cl⁻  +    SO₄²⁻
|-----------------------------------------|
  Oxidation number decreases
  from zero to -1   
step 1:-   Cl₂  -------------> 2Cl⁻  - 2e  [balanced reduction half reaction]
step 2 :-  SO₂  + 2H₂O  -------------> SO₄²⁻  + 4H⁺ + 2e
step 3 :- add equations of step 1 and step 2

               Cl₂  ----------> 2Cl⁻  - 2e
 SO₂  + 2H₂O ----------> SO₄²⁻ + 4H⁺ + 2e
_______________________________________
Cl₂ + SO₂ +2H₂O ------->2Cl⁻ + SO₄²⁻  balanced chemical reaction

Answer 2

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