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Conductometry- Introduction, Conductivity Cell, Conductometric Titrations, Applications

Conductometric titration is a quantitative technique that consists of replacing an ion with another. Conductometric titration application.
Conductometric titration is a quantitative technique that consists of replacing an ion with another, and invariably the ionic conductivity of the entrants differs with the entrant and so the conductivity varies during the titration. Plotting the change in conductance versus the addition of titrant allows the point of equivalence to be located. The conductometric titration curve should be optimized to minimize the error by keeping the angle between the two branches as small as possible. Conductance data whose angle is very obtuse can produce large deviations when a small error occurs. These approximate rules can be helpful.

As reactants are added to the reaction mixture, the conductivity of the mixture is continuously monitored by conductometric means. In this titration, conductometers are used to measure conductance. Therefore, it doesn't need an indicator since the conductance or the increase/decrease in the number of ions is measured by a conductometer. Due to its high titration efficiency, color solutions can be analyzed accurately. Conductometric titrations include several specific terms which need to be explained before its principle for you to better comprehend the subject.

Titrant - In a titration, a titrant is a solution whose concentration is known and which is titrated against a substance whose concentration is unknown.
Analyte - Taking titration measurements of a substance whose concentration is unknown.
Equivalent point - When conducting a conductometric titration at a constant concentration, the equivalence point occurs.

Strong Acids and Strong Bases: Conducted Titration

With NaOH as a powerful base and HCl as a strong acid, we can demonstrate this. The burette is filled with NaOH and the beaker is filled with HCl. Having the conductivity cell immersed in it and connecting it to a conductometer allows it to be measured. There is a mains switch connected to this conductometer. It's now switched on and we can interpret the results. A high conductance is present at the start of the titration because the solution contains H+ ions with high mobility. Titration proceeds by adding bases and as we make progress in the titration process the conductance falls because hydrogen ions replace OH- ions in NaOH and form water. Conductance thus declines. This process is repeated until equivalence is reached. When the solution reaches equivalence, it contains only sodium chloride. In solutions containing OH- ions, the conductance increases after the equivalence point.

Conductive cell

Pyrex or quartz electrodes are attached to the Pyrex or quartz body of the electrode. A vessel containing water should be used to keep the temperature constant. There are TYPE-A conductivity cells, TYPE-B conductivity cells, and TYPE-C conductivity cells.

Electrodes - The sheets of platinum, each 1 cm wide, are fixed one to another. A layer of platinum black has been applied to the surface to decrease polarization effects and increase effective surface area. The plating of electrodes is achieved by coating the electrodes with chloroplatinic acid and lead acetate solutions to form a uniform layer. An electrode's performance is determined by its conductivity & concentration.

Conductometric titration application

Especially for trace-level acid-base titration. Each level has greater than 1% relative precision. The method has some disadvantages, however. When too many electrolytes are present, conductance is affected, which is a non-specific property. Electrical conductance measures the capacity of an ionic solution to carry current. Therefore, the total ionic strength determines the electrical conductance. The conductance measurement becomes of no use unless the electrolyte can be identified with some degree of accuracy in the solution if there are no other ionic species present in it. Titrations using conductometric titrations are more precise and efficient, as they include neutralization, precipitation, and other methods for removing ions from the solution.
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Ankur Choudhary is India's first professional pharmaceutical blogger, author and founder of Pharmaceutical Guidelines, a widely-read pharmaceutical blog since 2008. Sign-up for the free email updates for your daily dose of pharmaceutical tips.
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