Model Experiment on Dynamic Equilibrium

Material Two identical 50 ml graduated cylinders, four 30 cm long glass tubes, two of 8 mm and two of 6 mm diameter. 

Procedure Fill one graduated cylinder with 50 ml of water (it models the amount of substance before equilibrium sets in), the other cylinder remains empty (no product initially). Hold two identical glass tubes (8 mm) in both hands, dip into both cylinders, close with index finger, lift out and transport the portion of water into the other cylinder. Repeat this procedure as many times as necessary until the water volumes in both cylinders no longer change. Repeat this experiment with glass tubes of different diameters. 

Observation At the end of the first test series, 25 ml of water is noted in each cylinder, the glass tubes can continue to transport water the 25 ml level remains the same. At the end of the second test series, 30 ml water is placed in one cylinder, in the other one 20 ml are measured, several repetitions of this transportation of water do not change the volumes of water. 

Tip The experiment shows not only a model of the dynamic forward and reverse reactions of a system in equilibrium but also the fact that, at equilibrium, one can have different amounts of matter, not always 50 50. Depending on conditions (for the model the diameters of both glass tubes), all other values should also be taken into account 40 60, 20 80, 10 90, etc. 

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An apple fight between an old man and the boy next-door [11] carries out a different model experiment on dynamic equilibrium. The boy is supposed to discard bad apples and just throws them into his neighbor s garden. The neighbor reacts and throws them back - his own garden is already full of apples ( large concentration ). Whereas the boy has to really hurry in order to collect his bad apples ( small concentration ), the old man effortlessly collects the same amount of apples, which he throws back. Finally, in balance, six apples are thrown in and six are returned (see Fig. 6.4) - despite different concentrations of apples on both sides. 

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