re: HSC Chemistry Marathon Archive
Method:
1) Label the two measuring cylinders; one marked “A” and the other “B”.
2) Place 100 ml of water in “A” and 0 ml of water in “B”.
3) Place the larger pipette upside down into “A” so that it rests vertically on the bottom, seal it tightly by finger pressure and transfer its contents to “B” without spillage. Place the smaller pipette upside down into “B”, seal and transfer the contents to “A”. This is one complete transfer cycle, and the volumes present in both “A” and “B” must be recorded.
4) Continue with a series of transfer cycles until a state of equilibrium is achieved (i.e. There is no further change in the volumes in “A” and “B”).
The experiment began with all the water in “A”, but at a point in time, both water levels were constant despite water still being transferred back and forth, which is representative of the concept of dynamic equilibrium. In this experiment the measuring cylinders A and B acted as the reactants and products respectively, whilst the large and small pipettes represented the reaction rates. Increasing the rate at which the water was transferred from one measuring cylinder to another via the pipettes, models the action of a catalyst. The transfer of liquid from “A” to “B” modelled the forward reaction, whilst the transfer of liquid from “B” to “A” modelled the reverse reaction. Therefore, this modelling investigation was valid as it applied accepted laws and all variables were controlled, baring the dependent and independent variables.
However, it did not show the reality of equilibrium systems, such as the reactants becoming products. Furthermore, the modelling of chemical equilibrium only allows for simplified representations of chemical processes that are based on assumptions, such as there being a closed-system at equilibrium when in reality there are minor inevitable spillages from the transfer cycles. Therefore, this experiment lacked validity in that, despite testing the aim, it was not entirely scientifically valid.
Overall, this experiment was a successful model for an equilibrium reaction.
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I'm not expecting too much from this and since Fizzycyst asked it I wouldn't be surprised if I got 1 / 5-6
Adding a basic substance such as ammonia would cause the equlibrium to shift to the right. This maximises the production of carbonic acid due to le chateliers principle. That is the main purpose of Ammonia. Without this the potential yield produced would be much smaller.
