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 ?
The constants k and n can be used to calculate the thermodynamic equilibrium constant ([K.
gt], calculated through the logarithmic expression of Eqn 3, and natural logarithm of equilibrium constant values obtained for binary equilibria, in [K.
21-3, as a function of the association equilibrium constants, are (18), (30):
For detailed insight into the process, particularly for a quantitative description of the structure-reactivity relationships as well as of the solvent effects, neat rate and equilibrium constants are required.
Giori and Hayes (1970) showed that the moisture content of molten nylons has a significant influence on the apparent equilibrium constant for polyamidation.
The latter reference reports an equilibrium constant of 0.
The equilibrium constants at reaction temperatures, 100[degrees]C, 110[degrees]C and 120[degrees]C were measured.
4 and 6 yields the curves of the equilibrium constant K and the condensation rate constant [k.
At equilibrium, the net rate is equal to zero, and the equilibrium constant can be expressed as

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