Plotting with Excel procedure

Note Use hypothetical data to practice plotting a standard curve with the Excel spreadsheet software procedure below. Later experiments will refer you back to this procedure to plot standard curves for real experiments. Launch Excel (or click hie then new if already launched) to begin. 

Data from tests at 250,275,300, and 325 C were used to calculate pseudo-first order rate constants for the formation of H2S. These data are expressed on a standard Arriienius plot (Fig. 2) for which the linear least squares coefficient of determination, r, is 0.98. The apparent activation energy calculated from the slope is 28.5 kcal/mol. This result is in excellent agreement with the recent work of Abotsi, who studied the performance of carbon-supported hydrodesulfurization catalysts (10). Using Ambersorb XE-348 carbon lo ed with sulfided ammonium molybdate (3% Mo loading) prepared by the same procedure reported here, Abotsi hydrotreated a coal-derived recycle solvent The apparent activation energy for... 

In an earlier procedure applying universal calibration, viscosities of the four most concentrated fractions eluting about the peak were measured, and the intrinsic viscosities were plotted against count. The intrinsic viscosities of all the fractions were obtained by extrapolation of the plot for use in the calculations to obtain degree of polymerization (DP). In the present method the DP of each fraction is obtained from the relationship MW = (cod size/K)1/1+ derived from Benoit s concept and the Mark-Houwink equation. Results from the new procedure are in excellent agreement with those obtained independently on cotton by others. Anomalies in results obtained previously on some samples disappear while marked improvement is noted for others. The determination is speeded up greatly by computer processing of data, and experimental error is reduced. 

Spreadsheet Summary In Chapter 4 of Applications of Microsoft Excel in Analytical Chemistiy, a multiple standard additions procedure is illustrated. The determination of strontium in sea water with inductively coupled plasma atomic emission spectrometry is used as an example. The worksheet is prepared, and the standard additions plot is made. The unknown Sr concentration and its standard deviation are obtained. 

While this procedure may certainly give an optimum value of n with respect to the Hnearity of the/(a,T) versus 1/T plot, the order determined may have no relationship to the molecularity of a transition state in the usual kinetic sense. The n value is usually called the index of reaction. In most cases, the results obtained from this type of analysis are similar to the kinetic parameter determined by conventional isothermal means, and in many cases the agreement is excellent. However, it must be remembered that the original rate law is assumed to have the form... 

The numerical integration procedure used to determine the specific rate constants gave excellent fits to the experimental data at all temperatures studied. In addition, the rate constants produced linear Frying plots. An independent check on the procedure was possible by comparing the rate constants, ki and k i, for isomerization of 3 obtained by the numerical fit to the analogous rates obtained(18) for this isomerization as it occurs in the absence of ArNH2 and methanol. Althc ugh the conditions of these two experiments differed with regard to the methanol concentration (5 vs. 0 M), the values of ki differed by only 7%. 

A flow chart for the procedures is shown in Figure 6. The main control program for the automated assay was programmed with Visual Basic . The e-sco unit was remotely controlled through its proprietary ActiveX interface. An EXCEL template file contained all relevant information about the sample and the desired automatic processing (number of samples, spectrum file names, peak position and line width). At the end of the assay, the measurement results and signal intensity plots are generated automatically. 

Following the procedure used for water but with wi = 0.37yN, the frictional force as a function of applied normal load was calculated and the results plotted in Figure 9 (middle curve). The agreement is excellent considering the approximations made and supports the contention that only wetting forces operate in the presence of NaCl. 

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