question_answer

When \[KMn{{O}_{4}}\] reacts with acidified \[FeS{{O}_{4}}\] [MP PET 1996]

A) Only \[FeS{{O}_{4}}\] is oxidised

B) Only \[KMn{{O}_{4}}\] is oxidised

C) \[FeS{{O}_{4}}\] is oxidised \[KMn{{O}_{4}}\] and is reduced

D) None of these

Correct Answer: C

Solution :

\[FeS{{O}_{4}}\]is oxidised and \[KMn{{O}_{4}}\] is reduced. \[2KMn{{O}_{4}}+3{{H}_{2}}S{{O}_{4}}\,\to \,{{K}_{2}}S{{O}_{4}}+2MnS{{O}_{4}}\]  \[[2FeS{{O}_{4}}+{{H}_{2}}S{{O}_{4}}\,\to \,F{{e}_{2}}{{(S{{O}_{4}})}_{3}}+2H]\times 5\] \[[2H+[O]\,\to \,{{H}_{2}}O]\times 5\] \[2KMn{{O}_{4}}+8{{H}_{2}}S{{O}_{4}}+10FeS{{O}_{4}}\,\to \]\[{{K}_{2}}S{{O}_{4}}+2MnS{{O}_{4}}+5F{{e}_{2}}{{(S{{O}_{4}})}_{3}}+8{{H}_{2}}O\] In this reaction oxidation state of \[Mn\] is changing from +7 to +2 while oxidation state of \[Fe\] is changing from +2 to +3.