AP EAMCET201922 Apr 2019Morning ShiftChemistryRedox ReactionsActual
(20 ~mL ) of ( Fe ²⁺ ) solution of certain concentration has completely reacted with (20 ~mL ) of (0.01 M K ₂ Cr ₂ O ₇ ) in acidic medium. If (20 ~mL ) of same ( Fe ²⁺ ) solution has reacted completely with (20 ~mL ) of ( KMnO ₄ ) solution in acid medium, the molarity of ( KMnO ₄ ) solution is
Options
- A(0.01 M )
- B(0.12 M )
- C(0.10 M )
- D(0.012 M )
Correct answer
D. (0.012 M )
Step-by-step solution
The reaction between ( Fe ²⁺ ) and ( Cr ₂ O ₇²⁻ ) (i.e. ( K ₂ Cr ₂ O ₇ )) in acidic medium occurs as follows : ( Cr ₂ O ₇²⁻+14 H ⁺+6 Fe ²⁺ 2 Cr ³⁺+7 H ₂ O +6 Fe ³⁺ ) The reaction between ( Fe ²⁺ ) and ( MnO ₄⁻ ) (i.e. ( KMnO ₄ )) in acidic medium occurs as follows : ( MnO ₄⁻+8 H ⁺+5 Fe ²⁺ Mn ²⁺+4 H ₂ O +5 Fe ³⁺ ) ( Cr ₂ O ₇²⁻ ) react with (6 Fe ²⁺ n₁ ) and ( MnO ₄⁻ )react with (5 Fe ²⁺ (n₂ ) ) in a balanced equation. Gram equivalent of ( Fe ²⁺ ) (= ) gram equivalent of ( K ₂ Cr ₂ O ₇ ) (= ) gram equivalent of ( KMn