IMAT 2011 Q69 [Oxidation Reduction]

Which one of the following is not an oxidation/reduction reaction?

A. {2Fe} + {3Cl_2}{2FeCl_3}
B. {Cl_2} + {H_2O}{HCl} + {HClO}
C. {KClO_4}{KCl} + {2O_2}
D. {NaCl} + {H_2SO_4}{NaHSO_4} + {HCl}
E. The electrolysis of sodium chloride solution

Reviewing each option carefully we can see:

In A-
Iron has been oxidised from 2Fe^0 -6e \rightarrow 2Fe^{3+}
Cholrine has been reduced from 6Cl^0 + 6e\rightarrow 6Cl^{-1}
This is a redox reaction.

In B-
Chlorine undergoes both oxidation and reduction itself;
Cl^0 -1e \rightarrow Cl^1
Cl^0 + e \rightarrow Cl^{-1}
This is a redox reaction.

In C-
Oxygen has been oxidized from 4O^{-2} - 8e \rightarrow 4O^0
Chlorine has been reduced from Cl^7 + 8e \rightarrow Cl^{-1}
This is a redox reaction.

In D-
All of the element’s oxidation states seem to remain the same; Na^{2+}, Cl^-, HSO_4^{2-}.This is not a redox reaction.

In E-
During the electrolysis of Sodium Chloride,
At the Anode (+); Chloride Ions are oxidized into Chlorine Gas.
Cl^- \rightarrow Cl_2 +2e

At the Cathode (-); Hydrogen Gas is evolved (reduced) in the case of a dilute solution and Sodium is formed in the case of a molten solution.
2H^+ + 2e \rightarrow H_2
Na^{2+} +2e \rightarrow Na
This is a redox reaction.

Therefore, we can confidently assume the answer is D.