Name: choosing oxidizing titrants in redox titration
Uploaded: 2024-12-05T18:31:57.000Z
Duration: 1 min 26 s
Channel: JoVE

In addition to iodine, several other oxidizing or reducing agents can be employed as titrants in redox titrations.
Potassium permanganate is a strong oxidizing titrant that reduces from manganese(VII) to manganese(II) in a strongly acidic solution.
Here, the purple permanganate acts as a self-indicator because manganese(II) is colorless.
Reducing analytes can also be titrated using acidic cerium(IV) solutions while using redox indicators for end point detection. In the titration, the analyte is oxidized while cerium(IV) reduces to cerium(III).
Potassium dichromate is a moderately strong oxidizing titrant that reduces from chromium(VI) to chromium(III) in acidic solutions. The dichromate end point is observed using a redox indicator.
In contrast, most reducing titrants are oxidized by atmospheric oxygen, so they are rarely used for the direct titration of oxidizing analytes.
For instance, thiosulfate is used indirectly as a typical reducing titrant for iodometric titrations.
However, an acidified iron(II) solution can be used to titrate some strong oxidizing analytes, such as cerium(IV), chromium(VI), and vanadium(V).

redoxtitratie: andere oxiderende en reducerende middelen

Redox Titration: Other Oxidizing and Reducing Agents

Naast jodium kunnen andere oxiderende of reducerende middelen dienen als titranten in redoxtitraties. Veelvoorkomende oxiderende titranten zijn KMnO_4, cerium(IV) en K_2Cr_2O_7. De keuze van oxiderende titranten hangt af van factoren zoals stabiliteit, kosten, analytsterkte en reactiesnelheid tussen de analyt en de titrant. KMnO_4 is een sterk oxiderende titrant die reduceert van Mn(VII) naar Mn(II) in een zeer zure oplossing, waarbij de analyt tegelijkertijd wordt geoxideerd tot een hogere oxidatietoestand. In dit geval fungeert KMnO_4 als een zelfindicator en wordt kleurloos na voltooiing van de reactie.

Reducerende analyten kunnen ook worden getitreerd met behulp van zure cerium(IV)-oplossingen, waarbij redoxindicatoren worden gebruikt voor eindpuntdetectie. De analyt wordt geoxideerd tijdens de titratie terwijl Ce(IV) reduceert tot Ce(III). Kaliumdichromaat (K_2Cr_2O_7), een matig sterk oxiderende titrant, reduceert tot Cr^3+ in zure oplossingen. Het dichromaat-eindpunt wordt waargenomen met behulp van een redoxindicator.


Daarentegen worden de meeste reducerende titranten geoxideerd door atmosferische zuurstof, waardoor ze ongeschikt zijn voor directe titratie van oxiderende analyten. Thiosulfaat wordt bijvoorbeeld indirect gebruikt als een typische reducerende titrant voor jodometrische titraties. Een verzuurde ijzer(II)-oplossing kan echter worden gebruikt om sommige sterk oxiderende analyten te titreren, zoals cerium(IV), chroom(VI) en vanadium(V).

Redoxtitratie: andere oxiderende en reducerende middelen

Besides iodine, other oxidizing or reducing agents can serve as titrants in redox titrations. Common oxidizing titrants include KMnO4, cerium(IV), and ...

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Education

JoVE Core

Analytical Chemistry

Analytische chemie

Unit 1

Electrochemical Analyses and Redox Titration

Elektrochemische analyses en redox-titratie

electrochemical-analyses-and-redox-titration

KEY TERMS AND CONCEPTS

KERNTERMEN EN CONCEPTEN

choosing oxidizing titrants in redox titration

Redox titrations can use oxidizing titrants other than iodine. Common choices include potassium permanganate (KMnO4), cerium(IV), and potassium dichromate (K2Cr2O7). The best titrant depends on stability, cost, analyte strength, and the reaction rate between the analyte and the titrant.

Potassium permanganate is a strong oxidizing titrant in highly acidic solution. It reduces from Mn(VII) to Mn(II) while it oxidizes the analyte to a higher oxidation state. KMnO4 also works as a self-indicator, so the solution turns colorless when the reaction is complete.

Cerium(IV) solutions can titrate reducing analytes in acidic conditions. During the reaction, the analyte is oxidized and Ce(IV) is reduced to Ce(III). A redox indicator is used to detect the endpoint.

Potassium dichromate is a moderately strong oxidizing titrant. In acidic solution, dichromate reduces to Cr3+, and a redox indicator is again used to spot the endpoint. Most reducing titrants are oxidized by atmospheric oxygen, so they are not suitable for direct titration of oxidizing analytes.

Thiosulfate is a common reducing titrant used indirectly in iodometric titrations. An acidified iron(II) solution can also titrate some strong oxidizing analytes, including cerium(IV), chromium(VI), and vanadium(V).

Choosing Oxidizing Titrants in Redox Titration

choosing-oxidizing-titrants-in-redox-titration

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Iodometry and iodimetry use iodine to measure unknown concentrations in redox titrations. These methods help determine the amount of an oxidizing or reducing agent in a sample. The key idea is that iodine changes color and reacts in a known stoichiometric ratio with the analyte. In iodometric titrations, the sample usually contains an oxidizing agent. The solution is acidified and then treated with an excess of iodide ions, which releases an equivalent amount of iodine in equilibrium with...

redox titration: other oxidizing and reducing agents

Redox titrations can use oxidizing titrants other than iodine. Common choices include potassium permanganate (KMnO4), cerium(IV), and potassium dichromate (K2Cr2O7). The best titrant depends on stability, cost, analyte strength, and the reaction rate between the analyte and the titrant. Potassium permanganate is a strong oxidizing titrant in highly acidic solution. It reduces from Mn(VII) to Mn(II) while it oxidizes the analyte to a higher oxidation state. KMnO4 also works as a self-indicator,...

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key terms and concepts

Explore how KMnO4, cerium(IV), and dichromate are used in redox titrations, how endpoints are detected, and why some reducing titrants are used indirectly.

Choosing Oxidizing Titrants in Redox Titration | JoVE K12

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Choosing Oxidizing Titrants in Redox Titration

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