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Difficulty: MediumOxidizing and Reducing Agents and Tests

Complete the statement below regarding the characteristic laboratory test observation and chemical role of acidified potassium tetraoxomanganate(VII) when reacted with iron(II) tetraoxosulfate(VI).

Answer:When acidified potassium tetraoxomanganate(VII) solution is added to a solution containing iron(II) tetraoxosulfate(VI), the purple color of the permanganate solution turns 【colorless】, because the permanganate ion acts as an 【oxidizing】 agent.

Answer

The purple solution turns colorless because potassium tetraoxomanganate(VII) acts as an oxidizing agent.
Acidified potassium tetraoxomanganate(VII) contains the intensely purple MnO4−MnO_4^- ion. Upon reacting with a reducing agent like Fe2+Fe^{2+}, the MnO4−MnO_4^- ion accepts electrons and is reduced to the colorless Mn2+Mn^{2+} ion. Because it removes electrons from iron(II) ions and oxidizes them to iron(III), potassium tetraoxomanganate(VII) functions as an oxidizing agent.

Step-by-Step Solution

1
Determine the color change of acidified potassium tetraoxomanganate(VII) when reacted with a reducing agent such as iron(II) ions.
The manganese in MnO4−MnO_4^- (purple) is reduced to Mn2+Mn^{2+}, which is colorless in dilute aqueous solution.
Permanganate ions undergo reduction from an oxidation state of +7 to +2 in acidic media.
2
Identify the chemical role of potassium tetraoxomanganate(VII) in this redox reaction.
Potassium tetraoxomanganate(VII) accepts electrons from iron(II) ions, converting Fe2+Fe^{2+} to Fe3+Fe^{3+}, making it an oxidizing agent.
A chemical species that causes another substance to be oxidized while undergoing reduction itself is defined as an oxidizing agent.

Key Concept

Laboratory test for reducing agents using acidified potassium tetraoxomanganate(VII)
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Topics

Oxidizing and Reducing Agents and Tests

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