Keq

To obtain a value for (Keq) then the pure stationary phase activity (aA), or the activity coefficient (ya) must be determined. It was argued that (ya) could be defined as follows,... 

The value of the equilibrium constant tells which side of the reaction arrow is energetically favored. If Keq is much larger than 1, then the product concentration term [C 4 [Dlrf is much larger than the reactant concentration term A " B, and the reaction proceeds as written from left to right. If Keq is near 1, appreciable amounts of both reactant and product are present at equilibrium. And if Koq is much smaller than l, the reaction does not take place as written but instead goes in the reverse direction, from right to left. 

Because the equilibrium constant, Keq, and the standard free-energy change, AG°, both measure whether a reaction is favored, they are mathematical related by the equation... 

Problem 5.11 Which reaction is likely to be more exergonic, one with Ktq = 1000 or one with Keq - 0.001 ... 

Schild analysis is a very powerful method to quantify the potency of a competitive antagonist and to test whether the blockade of response by a molecule is consistent with simple competitive antagonism. Devised by Arunlakshana and Schild (1959), it is based on the principle that the antagonist-induced dextral displacement of a dose-response curve is due to its potency (Keq value, affinity) and its concentration in the receptor compartment. Since the antagonism can be observed and the concentration of antagonist is known, the Keq (denoted KB for antagonist) can be calculated. Die relationship between antagonism and concentration must be log-linear with a unit slope to adhere to true competitive kinetics. 

Figure 4.4 Dependence of Keq on temperature for selected monomers. Based on values of A//pand ASp shown in Table 4.10.

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