Jason R. Green edited Theory.tex  over 9 years ago

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\section{Theory}  From the survival function, the time dependent rate coefficient is determined by taking various time derivatives of the survival function, depending on the total order of reaction. For first order irreversible decay reactions, $A\to B$, the rate law defines the time dependent rate coefficient  \begin{equation} k(t) \equiv  \frac{-d\ln S(t)}{dt}= k(t)  \end{equation} In traditional kinetics, irreversible decay is only dependent on one rate coefficient, $k(t)\to\omega$.  The time-dependent rate coefficient, $k(t)$, is determined by integrating the rate law of the reaction and forming a survival function from the integrated rate law.  In order to determine $k(t)$ in higher order reactions, we use the survival function, but it is not necessary. From the survival function, the time dependent rate coefficient is  \begin{equation}  k(t) = (\frac{d\frac{1}{(S(t)^{n-1)}}}{dt}) \equiv \frac{d}{dt}\frac{1}{(S(t)^{n-1)}}  \end{equation}  Taking our definitions of the integrated rate law, survival function, and time dependent rate coefficient, we are able to apply them to to second order irreversible decay. The integrated rate law in second order is  \begin{equation} 

From this survival function, taking the inverse of the survival function and then the time derivative yields the time dependent rate coefficient.  \begin{equation}  k(t) = \left(\frac{dS(t)^{-1}}{dt}\right) \frac{d}{dt}S(t)^{-1}  \end{equation}