Titration competitive

Figure 4.8. Histogram of the results (expressed as percent error) of the 1997 Royal Australian Chemical Institute titration competition held in Sydney.

Figure 4.10. Scatter plot of the results of team member A against the results for team member B of the 1997 Royal Australian Chemical Institute titration competition held in Sydney, for results that follow a normal distribution (in the bell of figure 4.8). Dashed lines show the assigned values of the concentration of each solution.

Hibbert, (2006), Teaching modern data analysis with the Royal Australian Chemical Institute s titration competition. Aust.J. Ed. Chem. 66, 5-... 

Yappert, M. C. DuPre, D. B. Complexometric Titrations Competition of Complexing Agents in the Determination of Water Hardness with EDTA, J. Chem. Educ. 1997, 74, 1422-1423. 

An example—the Royal Australian Chemical Institute titration competition... 

Although the above sounds plausible, do we have any evidence for these definitions of error Take as an example the Royal Australian Chemical Institute s (RACI) schools titration competition of 1997. In this competition, each of a team of three high school students is asked... 

Table 1.2 The results of the 1997 RACI titration competition. The values are independent students results for the concentration of a solution of acetic acid (units M). The correct answer was 0.1147 M...

Figure 1.2 Results of the 1997 RACI titration competition. Inset results for teams 3-20. The line is the accepted result (0.1147M) and the dashed lines are 1%. 

Figure 1.3 Histogram of the 1997 RACI titration results. Each bar is the number of students whose result fell between the number indicated and the number to the right. Note that the 25 data points in table 1.2 represent a subset of all the data from the RACI titration competition. The entire data set of 75 results was used to generate this histogram.

Therefore, if the concentration of acetic acid in the titration competition was determined as 0.1146 M with a 95% confidence interval of 0.0096 M then we could state the value of the concentration of acetic acid as 0.1146 0.0096 M (95% confidence interval). However if the uncertainty were 0.011M then the concentration would be expressed as 0.115 0.011 M (95% confidence interval). 

The RSD of an analytical result is often quoted as it gives an immediate impression of the precision of the measurement. Less than 1 % is usually considered very good for routine measurements which are more often in the 1-5% range. For the RACI titration competition (see chapter 1) the mean and standard deviation were 0.1146M and 0.0006 M, respectively, after removing outliers from consideration. The RSD was therefore 0.0006/0.1146 x 100% =0.5%, a very good result. 

The average and sample standard deviation are known as estimators of the population mean and standard deviation. We have seen how the estimates improve as the number of data increases. As we have stressed, the use of these statistics requires data that are normally distributed, and for confidence intervals employing the standard deviation of the mean this tends to be so. Real data may be so distributed, but often the distribution will contain data that are seriously flawed, as with the RACI titration competition described in chapter 1. If we can identify such data and remove them from further... 

Table 2.1 The results of 25 competitors in the 1997 RACI titration competition of the concentration of a test acetic acid solution in units of mol L 1...

Use robust estimators to estimate the population mean and population standard deviation for the RACI titration competition data shown in table 2.1. Outliers from a normal distribution are shown in italics (see section 3.4 for details of how to do this) and the median is in bold. 

For the RACI titration competition data the median is 0.1146M and the normalized interquartile range is 0.00098 M. 

Figure 3.3 Rankit plots for results of the RACI titration competition (a) All data (b) with extreme outlier at 0.9083 M removed (c) with seven outliers removed. Note the shrinking x-axis range.

A ring test proved that surfactant-selective electrodes are suitable for quantitative determination of anionic surfactants including alkanesulfonates [21]. The precision of this method, however, does not yet correspond to the state-of-the-art of the two-phase titration. Therefore, further development is needed to enhance the reproducibility and competitiveness of surfactant-sensitive titration. 

During the titration with the nitrogen base B (which as a titrant must be a stronger base than the solvent Py), there are the competitive acid-base reaction ... 

Figure 3.3 Substrate titration of steady state velocity for an enzyme in the presence of a competitive inhibitor at varying concentrations. (A) Untransformed data (B) data as in (A) plotted on a semilog scale (C) data as in (A) plotted in double reciprocal form. For all three plots the data are fit to Equation (3.1).

Table 3. Representative affinity constants for the binding of metal to transport sites or whole cells/organisms. Ionic strengths and pH values are given for the conditional constants. In the column Comments , information on the method of determination (Km = Michaelis-Menten constant WC = whole-cell titrations) the type of constant (CC = conditional constant IC = intrinsic constant) and special conditions (Cl = competitive inhibitors NICA = nonideal competitive adsorption) are given...

Each of the above liquid residues was tritrated against standard sodium hydroxide, using phenolphthalein as indicator. Identical titer values were obtained the same titer value was also given by the original solid residue of unreacted TBTA (0-1). Such an observation of identical titer Values should be expected if the conversion of TBTA, by reaction with sodium chloride, is solj.ly to TBTCl. However, any side reaction leading to TBT hydroxide or TBTO will result in lower titer values since these tin compounds, unlike TBTA or TBTCl cannot be titrated like weak acids. Clearly, the side reactions are not noticeable in these experiments. Hydrolysis is not competitive under the conditions of this study, probably because chloride concentration never drops below 10-1 whereas hydroxide concentration is always below 10 s. (It was noticed that the pH of the aqueous layer in each case had risen from 6.5 to 9.0.)... 

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