Experimental determination of the dissociation equilibrium constant. Ostwalds dilution law

17 EXPERIMENTAL DETERMINATION OF THE DISSOCIATION EQUILIBRIUM CONSTANT. OSTWALD S DILUTION LAW The dissociation equilibrium constant and the degree of dissociation at a given con-, centration are interlinked. To find this correlation let us consider the dissociation of a weak monobasic acid. The dissociation reaction can be written as 

The total concentration of the (undissociated plus dissociated) acid is c, thus the correlation 

If c or V is known and a is determined by one of the experimental methods mentioned in Section 1.10, K can be calculated by these equations. These equations are often referred to as Ostwald s dilution law, as they express the correlation between dilution and the degree of dissociation. As the latter is proportional to the molar conductivity of the solution, the above correlation describes the particular shapes of the conductivity curves shown in Fig. 1.3. 

The way in which dissociation constants are obtained from experimental data is illustrated in Table 1.7, in which the dissociation equilibrium constant of acetic acid is computed from molar conductivities. The average value 

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