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  • Author or Editor: J. Norwisz x
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Abstract  

Some preliminary considerations suggest that the so-called ‘compensation law’ is a result of the misinterpretation of evaluation procedure. The both parameters: pre-exponential factor and activation energy are calculated from the same set of experimental data. A confidence ellipse could describe the precision of these parameters. In the case of using the least square method for straight-line parameters evaluation, we could calculate a axes of the ellipse, using experimental data. If the observed relationship between pre-exponential factor and activation energy agree with the ‘pre-calculated’ direction of main axis of confidence ellipse, we have a strong support to believe that the observed ‘compensation’ effect is only an artificial effect of misinterpretation. Some calculations performed for a published experimental data have confirmed these suspicions. This also, indirectly indicates that precision of such experiments is probably lower than expected.

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The methods for determining kinetic constants may have significant effects on the estimation results. The two-variable linear correlation method leads to values of the kinetic constants for which the difference between the calculated and measured values is comparable to or greater than the measurement precision. The non-linear method for calculating kinetic constants by searching for the minimum of the error function , wherem i andm i are the measured and calculated values, respectively, andN is the number of experimental data, gives very precise results. A simple calculating technique is necessary for the fitting of the minimum point and the confidence region limit at the significance level. An appropriate calculation was made for metal oxidation according to the parabolic law.

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