Conductometric titrations advantage

Attention is finally focused on the advantages of conductometric titrations, which include (i) colored solutions where no indicator is found to function satisfactorily can be successfully titrated by this method (ii) the method is useful for titrating weak acids against weak bases, which does not produce a sharp change in color with indications in ordinary volumetric analysis and (iii) more accurate results are obtained because of the graphical determination of the end-point. 

Conductometric titrations offer several advantages compared with potentiometric titration methods, such as better precision and better differentiation of the basic components in polymers, but they are more laborious. ASTM D 4928-96 is an established KF method for the determination of water in crude oils. 

The advantages of the bipolar pulse technique include speed (discrete measurements at a rate as high as 30 kHz), accuracy, and signal-to-noise ratio. The system has been employed as a detector in automated conductometric titrations and in stopped-flow mixing systems with excellent results. 

The conductometric titration method has several advantages over the potentiometric titration method. It is applicable in a straight forward manner, without back titration or other modifications, to the determination of TBN for a wide range of petroleum products including fresh and heavily used oils. The conductometric method is quick and easy to perform, with two intersecting lines at the equivalent point, also contamination of electrodes is eliminated. The... 

An advantage of the conductometric titration is that it can be used for titrations based on relatively unfavorable equilibria. 

Advantages and Limitations of Radiometric Titrations. Radiometric detection of the equivalence point is a general method that does not depend on the chemical reaction employed. This contrasts with other methods of detection, which depend on specific chemical or physical transitions at the equivalence point. Amperometric titrations are applicable only to electrochemically active systems conductometric titrations apply only to ionic solutions, and so on. In principle, any titration system in which a phase separation can be effected is amenable to radiometric detection, provided there exist suitable radioactive labels. The major limitation of the method is the requirement for phase separation. In precipitation titrations, the phase separation is automatic and the method is well suited to this class of titrations. For other classes of titrations, special phase-separation methods, such as solvent extraction, need to be applied. At the present time, the method suffers from a lack of phase-separation techniques suitable for continuous monitoring of the titration curves. 

An estimation of the amounts of weak acid was made from direct titration on the samples (method D). Most oil samples have TAN of 1 to 2 units (mg KOH g 1 oil) however, samples 8 and 9 have an acidity index of around 4.5 units. Heat of neutralization of acidic products ranges from -3.7 to -20.4 kJ mol"1 and indicates the presence of weak acids in engine oil samples. The precision of calorimetric titration is comparable with conductometric and potentiometric methods. The advantages of calorimetric and conductometric techniques are rapidity, good reproducibility and avoidance of poisoning of detectors by organic substances. 

The electromotoric force (emf) of a cell depends on the ionic concentration of the solutions. To locate the equivalence point, the variation in emf is monitored as the concentration of the analyte changes. When the measured emf is plotted against the total volume of titrant added, the curve produced is similar to that of a titration curve Fig. 4. This technique has all the advantages of the conductometric method and gives an experimental curve from which the endpoint can be detected accurately. 

The prime advantage of polarisation titrations is the ability to handle reactions of poor equihbrium constant. This stems from the location of the endpoint by extrapolation to intersection from either side of the endpoint zone. This ability renders the method capable of carrying out titrations not easily possible by the potentiometric method. This characteristic is shared with other titration techniques (e.g., conductometric, photometric). 

Electrical methods of determining the end-point of titrations are widely used some of the advantages of the technique are obvious, such as the ability to titrate coloured solutions where the change of a visual indicator would be difficult or impossible to detect and the ability to carry out titrations for which no suitable visual indicator exists. Electrometric endpoints may often be employed with greater accuracy than visual ones and with greater sensitivity. It should always be remembered, however, that where a suitable visual method of end-point detection is available, it is usually more rapid and more economical to use. Electrometric methods may be classified into potentiometric, conductometric and amperometric methods. 

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