to water) and keep second cylinder (number ) empty. Put one tube in cylinder and second in cylinder . Immerse one tube in cylinder , close its upper tip with a finger and transfer the coloured water contained in its lower portion to cylinder . Using second tube, kept in nd cylinder, transfer the coloured water in a similar manner from cylinder to cylinder .
In this way keep on transferring coloured water using the two glass tubes from cylinder to and from to till you notice that the level of coloured water in both the cylinders becomes constant. If you continue intertransferring coloured solution between the cylinders, there will not be any further change in the levels of coloured water in two cylinders. If we take analogy of ‘level’ of coloured water with ‘concentration’ of reactants and products in the two cylinders, we can say the process of transfer, which continues even after the constancy of level, is indicative of dynamic nature of the process. If we repeat the experiment taking two tubes of different diameters we find that at equilibrium the level of coloured water in two cylinders is different.
How far diameters are responsible for change in levels in two cylinders? Empty cylinder ( ) is an indicator of no product in it at the beginning. Fig. .
Demonstrating dynamic nature of equilibrium. (a) initial stage (b) final stage after the equilibrium is attained. (a) (b) 2NH (g) N (g) + 3H (g) Similarly let us consider the reaction, H (g) + I (g) 2HI(g). If we start with equal initial concentration of H and I , the reaction proceeds in the forward direction and the concentration of H and I decreases while that of HI increases, until all of these become constant at equilibrium (Fig.
. ). We can also start with HI alone and make the reaction to proceed in the reverse direction; the concentration of HI will decrease and concentration of H and I will increase