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Question #44103
The Question
A aqueous solution at initially contains of an amphiprotic salt . The acid dissociation constants of the diprotic acid are and . To this solution, of and an excess of are added. The is completely reduced to by , which is oxidized to . Assuming no change in volume, that all escapes, and no is formed, what is the final pH of the solution?
(Given: , )
Options
- A.
7.18
- B.
5.00
- C.
7.60
- D.
6.82
Check Your Answer
Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Mechanism_Trap
Don't get tricked by the process! Learn the mechanical traps used in competitive exam questions.
Concepts Behind This Question
Amphiprotic Ion pH|KMnO₄ Redox pH Dependency|Successive Equilibrium Constants
Why This Question Is Tricky
Common Mistakes
This problem tests the coupling between redox stoichiometry and amphiprotic buffer equilibria.
The primary trap is assuming the pH remains constant at because is amphiprotic.
A secondary trap is failing to balance the overall redox reaction, mistakenly using the consumed in the permanganate half-reaction and ignoring the produced per oxidized, which would lead to an incorrect consumption of instead of .
Quick Facts About This Question
Question Information
| Subject | Chemistry |
| Chapter | Equilibrium - Class 11 Part 1 |
| Concept | Amphiprotic Ion pH |
| Difficulty | 8 |
| Cognitive Load | 7 |
| Target Solve Time | 160 sec |
| Access | Free |