Chlorine is used to purify drinking wate | Class 11 Chemistry Chapter Redox Reactions, Redox Reactions NCERT Solutions

Question:

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.

Answer:

The given redox reaction can be represented as:

Cl2(s)  + SO2(aq)  +  H2O(l)   →  Cl-(aq)  +   SO2-4(aq)

The oxidation half reaction is:

S+4 O2(aq)  →   S+6O2-4(aq)

The oxidation number is balanced by adding two electrons as:

SO2(aq)  →   SO2-4(aq)  + 2e-

The charge is balanced by adding 4H+ ions as:

SO2(aq)   →   SO2-4(aq)  +   4H+(aq) + 2e-

The O atoms and H+ ions are balanced by adding 2H2O molecules as:

SO2(aq)  + 2 H2O(l)   → SO2-4(aq)  + 4H+(aq) + 2e-      ..........(i)

The reduction half reaction is: The chlorine atoms are balanced as:

Cl2(s)    →  Cl-(aq) 

The oxidation number is balanced by adding electrons

Cl2(s)   + 2e-    →   2 Cl-(aq) ............(ii)

The balanced chemical equation can be obtained by adding equation (i) and (ii) as:

Cl2(s)   + SO2(aq)  + 2 H2O(l)   →   2 Cl-(aq)  + SO2-4(aq)  +  4H+(aq)


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Welcome to the NCERT Solutions for Class 11 Chemistry - Chapter . This page offers a step-by-step solution to the specific question from Excercise 1 , Question 23: Chlorine is used to purify drinking water. Excess of chlorine is harmful. The excess of chlorine is ....