equilibrium constant

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e·qui·lib·ri·um con·stant (Keq),

in the reaction A + B ⇄ C + D at equilibrium (that is, no net change in concentrations of A, B, C, or D), the concentrations of the four components are related by the equation Keq = [C][D]/[A][B]; Keq is the equilibrium constant If any component in the reaction has a multiplier (for example, H2 ⇄ 2H), that multiplier appears as an exponent in the calculation of K (for example, Keq = [H]2/[H2]). When this equation is applied to the ionization of a substance in solution, Keq is called the dissociation constant (Kd) and its negative logarithm (base 10) is the pKd.
See also: Henderson-Hasselbalch equation, mass:action ratio.
References in periodicals archive ?
As long as the values of C, m and n are known then we can calculate the stability constant (Kst) for the complex by using the equation (1).
Moreover, stability constants and stoichiometry can also be determined [9].
The space-time stability constant [C.sub.h] decreases with the number of time steps N, and, when N is large enough, approaches one (implicit midpoint rule) and two (backward Euler), respectively.
The stability constant values follow Irving-William order.
Table 7 records the values of x (number of mol HA/FA that combine with 1 mol arsenic) as well as logK (where K is the stability constant of arsenic-HA/FA complexes).
The present work aims to explore the coordination modes between Zinc(II) and hesperidin, to determine the complex stability constants, and the molecular structures and free charges of the Zinc(II)-hesperidin complex were optimized or calculated via semi-empirical calculation method using a Hyperchem software, to provide the theoretical reference for preparing this kind of complex in solution reaction system.
The study of complex formation and the determination of their stability constants have also been carried out indirectly, by using other groups, like a metallic ion, a second ligand, or [H.sup.+], which interact with one of the species in the main system and whose concentration can be accurately determined [23].
Nasu, "Determination of the stability constants for inclusion complexes of cyclo dextrins with various drug molecules by high performance liquid chromatography," Chemical and Pharmaceutical Bulletin, vol.
The calculation of the stability constant uses the change of the absorbance at the maximum wavelength of 208 nm for FOS as a function of [beta]-CD concentration.
Fitting of pH titration data for Pd(MME)-amino acid equilibria indicated the formation of 1 : 1 complexes with high stability constant values.

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