Potentiometry

Potentiometry is a method for measuring the potential difference between two electrodes to determine the concentration of a solute in a solution. Potentiometric titration involves monitoring the potentials of the indicator and reference electrodes, as the name indicates. Other titrations that employ other chemicals as indicators provide more precise and reliable results. Potentiometric titration is therefore preferred over manual titration. In 1893, Robert Behrend conducted the first potentiometric titration.

What is the definition of Potentiometric Titration?

Potentiometric titration is identical to direct titration except that instead of using an indicator reagent, an electrode is used. In potentiometric titrations, a cell with a reference electrode, salt bridge, analyte, and indicator electrode is employed. The electrolyte solution is used as an analyte for the most part. Hydrogen electrodes, silver chloride electrodes, and calomel electrodes are often used as reference electrodes. Two popular kinds of indication electrodes are glass electrodes and metal ion electrodes.

Titration Principle of Potentiometry potentiometric Titration Principle

The potential difference between two electrodes is revealed by the addition of a titrant or a change in ion concentration when they are submerged in a sample solution or analyte.

The two kinds of electrodes are reference electrodes and indication electrodes. The reference electrode retains its potential and remains steady when immersed in a sample solution. An indication electrode responds to changes in an analyte solution’s potential. To prevent analyte contact with the reference electrode, a salt bridge is utilized. The electric potential of the cell is determined by the concentration of ions in contact with the indicator electrode, as shown in the graph above. As a consequence, following each titrant addition, the Ecell is measured.

Method of Potentiometric Titration

Potentiometric titration is the measurement of the potential of an indicator electrode concerning a reference electrode as a function of titrant volume. We measured the cell potential after every addition of titrant in this titration. We begin administering titrants in very little doses as we move closer to the target. The most basic and extensively used way of endpoint detection in potentiometric titration is to plot a graph between cell potential and titrant volume. The midpoint of the graph’s or curve’s quickly ascending portion is visually assessed and utilized as the terminal. As seen in the graph below,

Types of Potentiometric Titration.

The principle of Potentiometry titration includes four types of titration: acid-base, redox, complexometric, and precipitation titration. Each of these titration techniques is briefly discussed below.

Acid-base titration: This kind of potentiometric titration is used to measure the concentration of an acid/base by accurately neutralizing it with a known standard base/acid solution.

Redox Titration: In this kind of Principle of Potentiometric titration, an analyte and titrant undergo a redox reaction. Titration of an iodine solution with a reducing agent to create an iodide ion is one kind of titration (a starch indicator is used to get the endpoint).

Titration based on Complexometry: This titration technique is also known as keratometry. In this process, a colored complex is formed to represent the titration’s endpoint. This method is used to determine the metal ion content of a solution.

Precipitation Titration: This titration technique involves contact between the analyte and the titrant, which results in the production of an insoluble precipitate. The titration is complete when the addition of the titrant no longer produces a precipitate.

The Benefits of Potentiometric Titrations

Potentiometric titrations are a kind of direct titration that does not need the use of an indicator. However, two electrodes, an indicator, and a reference electrode may exist in some setups. With milliliter accuracy up to three digits, this kind of titration is substantially more accurate and precise than manual titration.

Potentiometric titrations are available in a range of formats, with varied options dependent on the need to identify analytes. Examples are acid-base, redox, precipitation, and complexometric.

Potentiometry Slideshare titrations work effectively in automated systems with bigger sample processing capacities. While more advanced processes, such as high-performance liquid chromatography and capillary electrophoresis, may be used to determine pH, potentiometric titrations are less expensive and easier to execute. They can automate as well as calibrate software. These properties ensure that potentiometric titrations will continue to be useful in the future.

Conclusion

Titrations do not often need indicator solutions, however, they may make manual titrations using a burette easier. One of the most often used indicator solutions in acid/base titrations is phenolphthalein. When the pH is raised to 8.3, this indicator becomes a vivid pink color. Because the molecule of phenolphthalein is colorless, but its ion is, this works. As the solution becomes more basic, the molecule loses its H+ ions, and the ionized phenolphthalein produces its unique pink color. When the ionization process is complete, the indicator solution has turned the whole sample pink, signaling the conclusion of the experiment.