However, electrical conductance measurements can also be used as a tool to locate the end point, e. Electrochemists prefer to start with double layers on mercury for reasons of practice and principle. The conductometric titration curve is a plot of the measured conductance or conductivity values as a function of the volume of the NaOH solution added.

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The gap between the electrodes acts as a resistor, responding to differences in the conductivity of the migrating zone. Acid-base coonductometry and redox titrations are often performed in which common indicators are used to locate the end point e.


For this reason, on-column detection is rarely used. To suppress interfering redox reactions at the electrode surfaces measurements are typically made with Conduxtometry voltages at a frequency of about 1 kHz. The conductometric method is extremely temperature-sensitive, and cannot be used to measure overlapping p K a values. After the equivalence point is achieved the conductivity increases rapidly due to the excess OH- ions.

This, together with the advantages of operational robustness and a small effective detector volume, could result in the contactless conductivity detector acquiring a higher profile for ion detection.

The pressure and flow rate of the analyzed gas are controlled by a manostat and flow-meter; the gas then comes into contact with the conductometru reagent in the reaction space, where they react.

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Conductometry - Wikipedia

Marked increases or decrease in conductance are associated with the changing concentrations of the two most highly conducting ions—the hydrogen and hydroxyl ions. Conductometric methods are useful for the determination of substances in the concentration range from conduxtometry to hundreds of ppm.

The determination of a number of other gases HCl, HF, SO 2NH 3NO 2 is carried out using their absorption in deionized water, whose electrical conductivity is increased by the ions produced. Conductometry can be used to determine carbon dioxide by absorbing it in an aqueous suspension of BaCO 3.

However, it is preferable to employ a dilute NaOH solution 0. In addition to these sections, double layers have also been encountered in sec. The following reaction is employed in the determination of oxygen dissolved in water: Sensors and Actuators B: From Wikipedia, the free encyclopedia.

The determination of hydrogen sulphide is based on the reaction with an aqueous bromine solution: In other projects Wikimedia Commons.

Continuous SO 2 determination by conductometric measurements was discussed above. Conductometry has notable application in analytical chemistrywhere conductometric titration is a standard technique.

Sulphur dioxide is determined using its reaction with a dilute hydrogen peroxide solution, where the sulphuric acid produced increases the conductivity of the solution. As mentioned above, solubility is p K a -dependent, so if the solubility is measured at several pH values on a curve, such as is shown in Figure 15the p K a could be deduced.

The function of the suppressor see section 5. The solution conductivity before and after the reaction is measured by a differential method. They are employed primarily to measure emissions in the atmosphere and trace impurities in industrial gases, which affect technological processes e.

Fluorescence methods have the advantage of using very dilute drug solutions, and may be applicable in cases where UV methods are restricted.

2. Conductometry - Pharmaceutical Analysis [Book]

Thallium is inert in water, while thallium hydroxide produced by reaction with traces of oxygen is soluble in water and increases its conductivity. Therefore, in the conductometric method the most important property of the electrolytic solution, in conductomettry boundary layer, is its conductivity, which varies in accordance with quite a wide range of biological reactions.

For each amount of NaOH added equivalent amount of hydrogen ions is removed. By continuing you agree to the use of cookies.

Views Read Edit View history. Jaffrezic-Renault, in Biological Identification6. Poole, in The Essence of Chromatography

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