SCHEMATIC TABLES TO ILLUSTRATE CHE31ICAL EQCILIBRILII\I A. S. FEDOROW Chemical-TechnologicalInstitute, Charkow, U. S. S . R.
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ET US consider a reversible monomolecular reaction:
Let the initial concentration of the first substance (A) he 100, the initial concentration of the second substance (B), 100, the velocity constant of the first reaction (from left to right) kl be 0.5, the velocity constant of the second reaction (from right to left) k~ be 0.3. Such great values for the velocity constants are chosen in order to accelerate the establishment of the equilibrium and shorten the tables. During the first unit of time, as a result of the reaction from left to right, the concentration of the substance A is decreased and the concentration of the substance B is increased by 50 units of concentration, but during the same interval of time the concentration of the substance B is decreased and the concentration of the substance A is increased by 30 as a result of the reaction from the right to the left. At the end of the first unit of time the concentration of the substance A
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is 100 - 50 30 = 80, the concentration of the substance B is 100 - 30 50 = 120. During the second unit of time, as a result of the reaction from the left to the right, the concentration of the substance A is decreased and the concentration of the substance B is increased by 40, but during the same time, as a result of the reaction from right to left, the concentration of the substance B is decreased and the concentration of the substance A is increased by 36. At the end of the second unit of time the concentration of the substance A is 80 - 40 36 = 76, the concentration of the substance B is 120 - 36 40 = 124. In this way we can construct such a table as follows.
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It is easy to see that: 1. At the fifth unit of time we have a chemical equilibrium, as the loss of concentration of the substance A as a result of the reaction from left to right is the same as the increase of concentration of the same substance as a result of the reaction from right to left; the same is true for the substance B. 2. The ratio of the equilibrium concentration of the substance A to that of the substance B is the same as the ratio of the velocity constant kz to the velocity constant kl,namely:
Let the velocity constants of the reactions be the same as in the preceding case, the initial concentration of the substance A, 100, the initial concentration of the substance B, 0. The changes of the concentrations taking place in successive units of time may be demonstrated by the following table:
In the same manner tables for initial concentrations of lOOA 50B, for 50A 100B, or for any other desired combination may be constructed.
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