Name: endpoint detection in potentiometric titration
Uploaded: 2024-12-05T18:31:57.000Z
Duration: 1 min 31 s
Channel: JoVE

Potentiometric titrations determine the concentration of an analyte by measuring the potential difference between the reference and indicator electrodes in the solution following the addition of the titrant.
A sudden change in the titration curve, which is obtained by plotting the potentials against the titrant volume, indicates the end point of the titration.
Additionally, the endpoint can be more precisely identified from the maximum of the first derivative curve or the zero point from the second derivative curve.
Potentiometric titrations can involve acid&#8211;base, precipitation, complexometric, or redox reactions.
Acid&#8211;base titrations typically use glass electrodes to measure pH, which is plotted against titrant volume to identify the endpoint.
Precipitation titrations measure the potential derived from concentration changes in the anion or cation due to precipitation with an ion-selective electrode via the Nernst equation.
Ion-selective electrodes are also used in complexometric titrations to record the change in metal-ion concentration as a function of added complexing ligands such as EDTA.
Redox titrations employ inert metal electrodes, like platinum. Plotting the potentiometric titration curve alongside curves from different visual indicators helps develop an alternative visual indicator to potentiometric titration.

potentiometrische titratie: overzicht

Potentiometric Titration: Overview

Potentiometrische titratie is een kwantitatieve analytische techniek die de concentratie van een analyt bepaalt door het potentiaalverschil tussen de twee elektroden in de oplossing te meten. Het eindpunt van een potentiometrische titratie is het punt waarop er een significante verandering is in het potentiaalverschil. Het treedt op wanneer de stoichiometrische reactie tussen de analyt en de titrant voltooid is. Het eindpunt wordt meestal grafisch bepaald door het gemeten potentiaalverschil uit te zetten als een functie van het volume toegevoegde titrant. De resulterende grafiek wordt een titratiecurve genoemd. Afgeleide curven worden verkregen door de afgeleide van de titratiecurve uit te zetten met betrekking tot het volume toegevoegde titrant. Ze helpen om het eindpunt nauwkeuriger te identificeren. De afgeleide curve vertoont doorgaans een maximum- of minimumpunt bij het eindpunt, wat een nauwkeurigere eindpuntbepaling mogelijk maakt. Potentiometrische titratie is zeer veelzijdig en kan worden gebruikt voor zuur-base-, neerslag-, complexometrische of redoxreacties. Zuur-basetitraties gebruiken doorgaans glazen elektroden om de pH te meten ten opzichte van het titrantvolume.


Daarentegen gebruiken neerslagtitraties ionselectieve elektroden die zijn ontworpen om selectief te reageren op een bepaald ion in de oplossing. Redoxtitraties gebruiken daarentegen inerte metaalelektroden zoals platina, en de titratiecurve helpt bij het selecteren van een geschikte visuele indicator voor het titratieproces. Complexometrische titraties gebruiken ionselectieve elektroden om veranderingen in metaalionconcentratie vast te leggen door EDTA toe te voegen.

Potentiometrische titratie: overzicht

Potentiometric titration is a quantitative analytical technique that determines the concentration of an analyte by measuring the potential difference ...

Education

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Analytical Chemistry

Analytische chemie

Unit 1

Electrochemical Analyses and Redox Titration

Elektrochemische analyses en redox-titratie

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KEY TERMS AND CONCEPTS

KERNTERMEN EN CONCEPTEN

endpoint detection in potentiometric titration

Potentiometric titration is a quantitative analytical method used to find the concentration of an analyte by measuring the potential difference between two electrodes in a solution. The endpoint is the point where this potential changes sharply. It usually appears when the stoichiometric reaction between the analyte and the titrant is complete.

To find the endpoint, the measured potential difference is plotted against the volume of titrant added. This graph is called a titration curve. A derivative curve can also be made by plotting the change in the titration curve with respect to titrant volume. The endpoint is easier to spot on this curve because it often shows a maximum or minimum at that point.

This method is useful for several kinds of reactions, including acid-base, precipitation, complexometric, and redox titrations. Acid-base titrations often use glass electrodes to measure pH as titrant volume increases. Precipitation titrations use ion-selective electrodes that respond to a specific ion in the solution. Redox titrations use inert metal electrodes such as platinum, and the titration curve can help choose a suitable visual indicator. Complexometric titrations use ion-selective electrodes to track metal-ion concentration as EDTA is added.

Endpoint Detection in Potentiometric Titration

endpoint-detection-potentiometric-titration

electrochemistry: overview

Electrochemistry and Redox Reactions

Electrochemistry connects electrical measurements with chemical reactions, especially oxidation and reduction. It focuses on how electron movement helps explain reaction behavior. Oxidation is the loss of electrons from a substance, and reduction is the gain of electrons. A species with strong electron affinity is an oxidizing agent, or oxidant. A species that donates electrons is a reducing agent, or reductant. These redox steps are often described with half-reactions. When electrons move...

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Types of Electrodes in Electrochemistry

Electrodes are conductive materials in an electrochemical cell. They allow electron transfer reactions to happen at their surfaces. Electrochemical measurements use them to control and measure current and potential. The working electrode, also called the indicator electrode, is the main sensing electrode. Its potential changes with the analyte concentration and with the activity of the electroactive species. Common indicator electrodes include inert platinum electrodes, silver electrodes that...

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Reference and Indicator Electrodes in Potentiometry

Potentiometric measurements use reference electrodes and indicator electrodes to track changes in a solution. A reference electrode gives a stable baseline, while indicator and working electrodes respond to changes in the solution’s composition. The Standard Hydrogen Electrode, or SHE, is a common reference electrode. It keeps a zero potential at all temperatures. However, it needs a continuous supply of hydrogen gas, so it is not practical for routine use. The Saturated Calomel Electrode, or...

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Redox titration uses electron transfer in a redox, or reduction-oxidation, reaction to find the concentration of an unknown solution. The titrant has a known concentration, and it is added gradually to the analyte, which is the solution being tested. The endpoint shows when the reaction between the two substances is complete. Before a redox titration begins, the analyte should be in a single oxidation state. If needed, this is done by pre-oxidizing or pre-reducing the sample with an auxiliary...

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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,...

potentiometric titration: overview

Potentiometric titration is a quantitative analytical method used to find the concentration of an analyte by measuring the potential difference between two electrodes in a solution. The endpoint is the point where this potential changes sharply. It usually appears when the stoichiometric reaction between the analyte and the titrant is complete. To find the endpoint, the measured potential difference is plotted against the volume of titrant added. This graph is called a titration curve. A...

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A Gran plot helps predict the endpoint of a potentiometric or acid-base titration before the endpoint is reached. It uses titration data collected only up to a point that is still below the equivalence volume. The data are then transformed into a straight-line format. To build the plot, the line is extended to the x-axis. That x-intercept shows the titrant volume needed to reach the equivalence point. In potentiometric titration, the Gran plot uses the volume-corrected base-10 antilogarithm of...

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Electrically Generated Reagents in Titration

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key terms and concepts

Learn how potentiometric titration uses electrode potential, titration curves, and derivative plots to identify endpoints in acid-base, redox, precipitation, and complexometric reactions.

Endpoint Detection in Potentiometric Titration | JoVE K12

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JoVE Core Analytical Chemistry simplifies complex chemical principles by breaking them down into clear, engaging animations, making topics from SI Units to NMR spectroscopy more accessible and straightforward. Additionally, the scientist-in-action videos highlight the application of these concepts in real-world research conducted in laboratories globally.

Endpoint Detection in Potentiometric Titration

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