Name: electrode weighing in electrogravimetric analysis
Uploaded: 2024-12-05T18:31:57.000Z
Duration: 1 min 30 s
Channel: JoVE

Electrogravimetric analysis determines an analyte&#39;s mass in a sample solution by electrolytically depositing it onto a suitable pre-weighed working electrode.
Applying the appropriate potential deposits the analyte through metal cation reduction at the cathode or oxidation at the anode, or even through oxidation of the anode metal itself.
The electrode&#39;s increase in weight after deposition gives the analyte&#39;s weight in the solution.
The deposition completeness can be evaluated by exposing the fresh electrode surface to the used solution while continuing the electrolysis and checking for new deposits.
Other methods include observing the disappearance of a colored analyte or quantitatively testing for the analyte using a spectrophotometer.
Quantitative analyte deposition requires an overpotential&#8212;a potential past the Nernst equilibrium potential&#8212;because an underpotential often favors the formation of a monolayer on the electrode surface over bulk metal deposition.
In a constant-current method, the overpotential may cause unwanted reactions that affect the accuracy of the analysis. Depolarizers prevent these reactions by scavenging excess electrons into non-interfering reactions.
In addition, controlling the working electrode&#39;s potential can help avoid unwanted side reactions that change the mass of the analyte deposited.&#160; &#160;

elektrogravimetrische analyse: overzicht

Electrogravimetric Analysis: Overview

Elektrogravimetrische analyse meet het gewicht van een analyt die elektrolytisch op een geschikte werkelektrode is afgezet. Deze methode omvat het toepassen van een potentiaal op een vooraf gewogen elektrode die in een oplossing is ondergedompeld, wat resulteert in het afzetten van de gewenste substantie door reductie bij de kathode of oxidatie bij de anode. Het gewicht van de elektrode wordt na depositie geregistreerd en het verschil in gewicht geeft het gewicht van de analyt in de oplossing.

Om de volledigheid van de afzetting te testen, wordt het verse elektrodeoppervlak blootgesteld aan de oplossing terwijl de elektrolyse wordt voortgezet en er wordt gecontroleerd op nieuwe afzettingen. De afwezigheid van nieuwe afzettingen betekent dat de reactie is voltooid. Andere tests omvatten het controleren op kleurverdwijning of het uitvoeren van een kwalitatieve test voor de analyt in de oplossing.


Onderpotentiaal Afzetting, of monolaagvorming op het elektrodeoppervlak, vindt plaats bij een potentiaal onder het Nernst-evenwichtspotentiaal. Omgekeerd is overpotentiaal (een potentiaal boven het Nernst-potentiaal) vereist voor bulkmetaalfilmafzetting. Overpotentiële factoren kunnen ongewenste reacties veroorzaken en de nauwkeurigheid van de analyse beïnvloeden.


Depolarisatoren kunnen worden toegevoegd om ongewenste nevenreacties te voorkomen door overtollige elektronen in niet-interfererende reacties te vangen en het potentieel van de werkende elektrode te regelen.

Elektrogravimetrische analyse: overzicht

Electrogravimetric analysis measures the weight of an analyte deposited electrolytically onto a suitable working electrode. This method involves applying ...

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Analytical Chemistry

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Electrochemical Analyses and Redox Titration

Elektrochemische analyses en redox-titratie

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KEY TERMS AND CONCEPTS

KERNTERMEN EN CONCEPTEN

electrode weighing in electrogravimetric analysis

Electrogravimetric analysis measures an analyte by weighing the material that deposits on an electrode. A pre-weighed working electrode is placed in solution, and a potential is applied. The target substance then deposits by reduction at the cathode or by oxidation at the anode.

After electrolysis, the electrode is weighed again. The mass increase gives the weight of the analyte in the solution. To check that deposition is complete, the fresh electrode surface is exposed to the solution while electrolysis continues. If no new deposit forms, the reaction is finished.

Other checks can also be used. The solution may lose its color, or a qualitative test can show whether any analyte remains. These signs help confirm that the measured mass reflects the full amount of deposited material.

The process also depends on electrode potential. Underpotential deposition is monolayer formation on the electrode surface at a potential below the Nernst equilibrium potential. Bulk metal film deposition needs overpotential, which means a potential above the Nernst potential.

Overpotential can lead to unwanted reactions and reduce accuracy. Depolarizers may be added to limit these side reactions. They do this by scavenging excess electrons into non-interfering reactions and helping control the working electrode potential.

Electrode Weighing in Electrogravimetric Analysis

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electrochemistry: overview

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Electrogravimetric analysis measures an analyte by weighing the material that deposits on an electrode. A pre-weighed working electrode is placed in solution, and a potential is applied. The target substance then deposits by reduction at the cathode or by oxidation at the anode. After electrolysis, the electrode is weighed again. The mass increase gives the weight of the analyte in the solution. To check that deposition is complete, the fresh electrode surface is exposed to the solution while...

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key terms and concepts

Learn how electrogravimetric analysis uses a pre-weighed electrode, mass gain, and deposition checks to measure an analyte in solution.

Electrode Weighing in Electrogravimetric Analysis | JoVE K12

analytical chemistry

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Electrode Weighing in Electrogravimetric Analysis

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