IBM 1620 computer prepares tables to enable fast calculation of the first- and second-order rate constants from two half-lives and the corresponding initial concentrations, obtained from either one or two decay curves

Schmidt, K. H.

English

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December 1970	 Brief 70-10608 
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Evaluation of Decay Curves of a Chemical Species Undergoing

Simultaneous First- and Second-Order Decay 
Tables which facilitate determining, from two meas-
ured half-lives, the first- and second-order com-
ponents of the decay curve of a chemical species 
have been derived. 
In pulse-radiolysis studies, the formation and decay 
of transient chemical species are directly observed 
on an oscilloscope. The traces can be used for 
calculating the rate constant for a first- (pseudo 
or real) or second-order reaction of the species 
under investigation. For a pure first- or second-
order reaction, the usual evaluation method involves 
plotting, respectively, the logarithm or the reciprocal 
of the concentration against time, and measuring 
the slope of the resultant straight line. This pro-
cedure can also be used for a predominantly second-
order decay with a small first-order component, 
or vice versa, for which there is a small devia-
tion from the straight line at one end of the curve. 
However, if the first- and second-order components 
are of the same order of magnitude, analyzing the 
decay curves is more complex. The tables, computed 
with an IBM-l620 digital computer, enable fast calcu-
lation of the first- and second-order rate constants 
from two half-lives and the corresponding initial 
concentrations, obtained from either one or two 
decay curves. 
Note: 
The following documentation may be obtained 
from:
National Technical Information Service 
Springfield, Virginia 22151 
Single document price $3.00 
(or microfiche $0.65) 
Reference: 
ANL-7400 (N68-25700), Tables for the 
Evaluation of Decay Curves of a Chemical 
Species Undergoing Simultaneous First- and 
Second-Order Decay
Source: K.H. Schmidt of

Argonne National Laboratory

(ARG-1028 1) 
Category 03 
This document was prepared under the sponsorship of the Atomic 
Energy Commission and/or the National Aeronautics and Space 
Administration. Neither the United States Government nor any per-
son acting on behalf of the United States Government assumes any
liability resulting from the use of the information contained in this 
document, or warrants that the use of any information, apparatus, 
method, or process disclosed in this document may not infringe pri-
vately owned rights.
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Evaluation of decay curves of a chemical species undergoing simultaneous first- and second-order decay

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