Biology Forums - Study Force

A sample of pure tin metal is dissolved in nitric acid to produce 15.00 mL of solution containing Sn2+.  When this tin solution is titrated, a total of 42.1 mL of 0.145 mol/L KMnO4 is required to reach the equivalence point.


b.    What is the concentration of the Sn2+ solution?

  Find the concentration of the Sn2+(aq) in mol/L:  (give your answer to 3 decimal places)

Complete balanced overall redox reaction is:

16 H+ + 5Sn2+ + 2MnO4- → 2Mn2+ + 5Sn4+ + 8H2O

Explanation:

In acidic medium, potassium permanganate acts as a strong oxidizing agent. An oxidizing agent oxidizes the substrate present in the solution and gets reduced in the process. When an acidic solution of tin reacts with potassium permanganate, it oxidizes tin from its +2 oxidation state to +4 oxidation state. Simultaneously, Mn from +7 oxidation state gets reduced to +2 oxidation state. The individual oxidation and reduction reaction can be expressed as:

Reduction reaction: 8H+ + MnO4- + 5e-→ Mn2+ + 4H2O ......(1)

Oxidation reaction: Sn2+ → Sn4+ + 2e- ......(2)

To cancel out the electrons, multiply equation (1) by 2 and equation (2) by 5, we get

16H+ + 2MnO4- + 10e-→ 2Mn2+ + 8H2O ......(3)

5Sn2+ → 5Sn4+ + 10e- ......(4)

Adding equation (3) and (4), we get the complete balanced redox reaction equation as:

16 H+ + 5Sn2+ + 2MnO4-→ 2Mn2+ + 5Sn4+ + 8H2O

Here, Mn in +7 oxidation state shows violet color and on getting reduced to +2 oxidation state becomes colorless. Therefore, acting as a self-indicator in this reaction. +2 oxidation state is the most reduced form of manganese and thus indicates the end point of the titration.

Please mark the topic solved if you're happy polishprodigy93 (https://biology-forums.com/index.php?action=profile;u=845988)

Otherwise, reply back for more explanations ;D

Content hidden