first-order kinetics

first-order kinetics

a chemical reaction in which the rate of decrease in the number of molecules of a substrate is proportional to the concentration of substrate molecules remaining. In first-order reactions involving two substances, only one of the concentrations affects the rate. The rate of metabolism of most drugs follows the rule of first-order kinetics and is independent of the dose. Also called first-order reaction. See also kinetics.
References in periodicals archive ?
The rate of detachment of active chains from their junctions was expressed by an Eyring type equation, while the number of active chains could be calculated by a first-order kinetics.
In order to determine the rate and drug transport mechanism of Clarithromycin from controlled release tablets, the dissolution profiles were fitted in various kinetic/mathematical models given as under Zero-Order Kinetics (W=K1t), First-Order Kinetics [ln (100-W)=In100-K2t], Higuchi Kinetics (W=K4 t ) Hixson Crowell Kinetics (100-W) 1/3 =1001/3-K3t), Korsmeyer's Peppas's Kinetics (Mt/M8 = K5tn).
The Langmuir-Hinshelwood model mentioned equivalent to concern with the pseudo first-order kinetics of photocatalytic degradation of basic azo dyes [2].
Conversely, the first-order kinetics degradation constant decreased in an identical way for all COD-treatments.
The model assumes that the US chamber is the completely mixed flow-through (CMF) system, the UV chamber is the plug-flow with dispersion (PFD) system, and a reaction follows the first-order kinetics.
Several researchers, however, have questioned the possibility of the presence of multiple, independent retention sites and stated that a gradual change in slope from one time increment to the next was prevalent, indicating a continual change in the apparent rate constant (kD and precluding the operation of strictly first-order kinetics for the entire course of reaction time (Jopony and Young 1987; Allen et al.
In this context, first-order kinetics could be used to evaluate kinetic reaction and rate of current catalytic reaction as shown (Fig.
PME inactivation followed first-order kinetics with a residual PME activity of 15% at all pressure-temperature combinations used by the researchers.
First-order kinetics mandates on/off symmetry, which means that the change in V[O.
7), for the first-order kinetics a plot of ln(1-[alpha]) against t will yield a straight line, with a slop equal to -k.
The degradation of polymer was included into the models under the premise of first-order kinetics for the chain scission [80].
The above rate law equation explain fully well the experimental results obtained for the first-order kinetics, the plot of 1/[rate] versus 1/[substrate] give rise a straight line with positive intercept which gives the value of k and furnishes an evidence for the formation of complex between substrate and reactive species of the oxidant.

Full browser ?