Kinetic missing values

De Tar and Day [498] considered problems which arise in applying the first-order expression [eqn. (15)] to kinetic data of limited accuracy. If a is known to a high degree of accuracy (e.g. 0.1%), then small components (5—10%) of higher or lower order behaviour are detectable. When the accuracy of a is reduced to 1%, a second-order component of 25% could escape detection, and perhaps an even larger contribution might be missed within a limited a interval. Using exact values of a from known kinetic behaviour, the apparent rate coefficient, ft, was found to depend on both the proportion of the non-first-order component and on the extent of reaction considered. 

The use of the data of a single experiment to obtain an average value of the rate coefficient is inadvisable. In the first place, any estimate of the precision of the rate coefficient is necessarily of limited significance it is for this reason that we have not devoted any attention to this quantity in our previous discussion. In the second place, although unlikely in the case under discussion, complications in the kinetic behaviour may well be missed if the a, t data are only available for one pair of [A]o and [B]q values. 

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