USING SIR DYNAMIC TO MODEL CHEMICAL EQUILIBRIUM
The first SIR in the chemical equilibrium sequence is SIR DYNAMIC. Here’s what it looks like. It represents a simple one-to-one reversible reaction, such as an isomerism, on both the microscopic and macroscopic scales. Reactant and product are consistently colour-coded.
One may start with any proportions of reactant and product. This example contrasts two reactions, one starting with 100% reactant and one with100% product. Notice that you can retain a previous plot, so as to compare it with the current one.
The dynamics of the reaction may be determined by the equilibrium constant and effective rate constant, by DG and Ea (as in the example), or by the forward and back rate constants. In this case, a small negative DG and a large activation energy have been chosen.
There are other useful facilities, which you may discover by way of the HELP button.
In the course of a live run, the microscopic system on the left will still show reaction after change ceases in the macroscopic system. This demonstrates that, even when equilibrium is reached and nothing seems to be happening on the macro-scale, both reactions are still running. It’s a dynamic equilibrium. This example also shows that the reaction appears to be heading for the same place from opposite directions. One may show that this is so by lowering the activation energy, or by increasing rate constant(s) appropriately in the other modes.
You might start a presentation of equilibrium with SIR DYNAMIC, or you could go directly to the real reactions in SIR Q. If you start with SIR Q, which lets you discover the law of chemical equilibrium, you might then bring in SIR DYNAMIC at appropriate moments during that process. This illustrates the most important point about the SIRs – they are tools to use as you wish.
Click here to see how you can use SIR Q to follow real reactions to equilibrium