rate constants


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rate con·stants (k),

proportionality constants equal to the initial rate of a reaction divided by the concentration of the reactant(s); for example, in the reaction A → B + C, the rate of the reaction equals -d[A]/dt = k1[A]. The rate constant k1 is a unimolecular rate constant because only one molecular species is reacting and has units of reciprocal time (for example, s-1). For the reverse reaction, B + C → A, the rate equals -d[B]/dt = d[A]/dt = k2[B][C]. The rate constant k2 is a bimolecular rate constant and has units of reciprocal concentration-time (for example, M-1 s-1).
Synonym(s): velocity constants

rate con·stants

(k) (rāt kon'stănts)
Proportionality constants equal to the initial rate of a reaction divided by the concentration of the reactant(s); e.g., in the reaction A → B + C, the rate of the reaction equals -d[A]/dt = k1[A]. The rate constant k1 is a unimolecular rate constant, since there is only one molecular species reacting, and has units of reciprocal time (e.g., sec-1). For the reverse reaction, B + C → A, the rate equals -d[B]/dt = d[A]/dt = k2[B][C]. The rate constant k2 is a bimolecular rate constant and has units of reciprocal concentration-time (e.g., m-1 sec-1).
References in periodicals archive ?
Table-2: Rate constants and statistical analysis of the effect of temperature over swelling rate.
where [Kd.sub.1] is the decomposition rate constants of the primary initiator.
Apparent rate constants (k) at different temperatures were obtained from the slope of the linear plots in Fig.
Based on acquired potential energy surface information of [C.sub.2][H.sub.5] + NCO reaction, rate constants of the overall reaction and multiple reaction channels as well as branching ratio of various products at the temperature range 200~2000 K and pressure range 1~7600 Torr were calculated with MultiWell 2011 program [27, 37].
Effects of variations in pH on observed rate constants of the reaction
developed a detailed mechanism for [PODE.sub.1] through estimation of the rate constants, and investigated the oxidation of [PODE.sub.1] in a JSR [27].
Coefficients [k.sub.ij] describe the corresponding reaction rate constants in Scheme 2.
The values of the three rate constants, [k.sub.d], [k.sub.off], and [k.sub.on], have been determined for each drug-loaded sample and MTP by fitting the experimental release profiles with (2) (Table 2).
As illustrated by the kinetic parameters presented in Table 2, despite the fact that vacuum frying was achieved at reduced frying temperature, the rate constants were close in magnitude to those obtained during atmospheric frying for the colour parameters.
Reaction in the water make minor contribution to the observed rate constant. The first order rate constant for [K.sub.[PSI]] OH ion is given by the following equation:
The correlation between reaction rate constants and activation energy can be obtained using Arrhenius equation.