Redox titration evaluation

To evaluate a redox titration we must know the shape of its titration curve. In an acid-base titration or a complexation titration, a titration curve shows the change in concentration of H3O+ (as pH) or M"+ (as pM) as a function of the volume of titrant. For a redox titration, it is convenient to monitor electrochemical potential. 

After the total amount of the analyte 1 is oxidized, the potential changes become fast again as long as the oxidizing potential of the next analyte is achieved. Therefore, a transient slightly resembling a multiple redox titration curve is obtained. The transition times needed for the oxidation of the deposited metals are used for the evaluation. The peak shaped diJdE versus E plot makes the evaluation more convenient. 

One of the most important applications of redox titrimetry is in evaluating the chlorination of public water supplies. In Method 9.3 an approach for determining the total chlorine residual was described in which the oxidizing power of chlorine is used to oxidize R to 13 . The amount of 13 formed is determined by a back titration with 8203 . 

A proper description of electronic defects in terms of simple point defect chemistry is even more complicated as the d electrons of the transition metals and their compounds are intermediate between localized and delocalized behaviour. Recent analysis of the redox thermodynamics of Lao.8Sro,2Co03. based upon data from coulometric titration measurements supports itinerant behaviour of the electronic charge carriers in this compound [172]. The analysis was based on the partial molar enthalpy and entropy of the oxygen incorporation reaction, which can be evaluated from changes in emf with temperature at different oxygen (non-)stoichiometries. The experimental value of the partial molar entropy (free formation entropy) of oxygen incorporation, Asq, could be... 

An excellent example of the application of ICTs at OTEs to the study of a mixture of cytochrome c and cytochrome c oxidase is shown in Figure 9. In this experiment, each titration increment is 1.04 x 10 equivalents and methyl viologen was the reductive mediator. In addition to evaluating the n value of cytochrome c and the n values of each heme of cytochrome c oxidase, the data of Figure 9 can be plotted in log-log form for the ratios of the redox states of the two sample components as shown in Figure 10. Knowing the... 

T raditionally, titration curve calculations are described in terms of equations that are valid only for parts of the titration. Equations will be developed here that reliably describe the entire curve. This will be done first for acid-base titration curves. In following chapters, titration curves for other reaction systems (metal complexation, redox, precipitation) will be developed and characterized in a similar fashion. For all, graphical and algebraic means of locating the endpoints will be described, colorimetric indicators and how they function will be explained, and the application of these considerations to (1) calculation of titration errors, (2) buffo design and evaluation, (3) sharpness of titrations, and finally, (4) in Chapter 18, the use of titration curve data to the determination of equilibrium constants will be presented. 

The bismuth forms a sparingly soluble metal complex with the pyrrolidine dithiocarbamate. The potentiometric method of titration is highly sensitive for small quantities of bismuth. An evaluable jump is still obtained with the standard solution. However, no explanation has yet been given as to why there is a potential jump at all. During potentiometric titration there is presumably a small quantity of a reversible oxidation product present, with the result that a measurable redox potential may be formed between the... 

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