from linearity, which may be attributed to the gradual decrease in the diffusion during the later part of the exchange reaction. From the initial slope of the plot, the value of k was calculated.
RESULTS AND DISCUSSION
The values of the rate constant, k , were calculated using the procedure given above over a range of values of b from about 1.1 to 0.12 meq./l. It was observed that the value of k obtained was practically independent of the value of b. The value of k was also within about +5% for the four cinchona alkaloid sulfates studied for each resin used. The values of k thus obtained are given for resins X1, X2, and the three particle sizes of X4 in Table and". The value of the apparent energy of activation for each of these resins was evaluated according to the Arrhenius equation (7) and is almost the same, 3.06 kcals.
Similarly, runs were carried out at 35 and 45" for the three particle sizes of the resin (Amberlite-200) with four cinchona alkaloid sulfates and the same conclusions were obtained. The values of k are given in Table . The value of apparent energy of activation is higher, and is 5.19 kcals. The value of k is inversely proportional to the average particle diameter, a, as indicated by the values of k and u.
The observation that the value of k is almost the same for the four cinchona alkaloid sulfates indicates that for the expanded structure resin, the rate of exchange is practically the same although the value of PK (which gives the value of equilibrium exchange) (2) is higher for cinchonine sulfate and cinchonidine sulfate than that for quinine sulfate and quinidine sulfate.