Pseudo-steady state and open or closed systems

Pseudo-steady state and open or closed systems 

In the examples of psendo-steady state solutions that we have computed above, we have never nsed the eqnations of conservation of elements, which means we have never needed to specily whether our calculation was valid in a closed system, an open or a partially open system. This comes from the fact that we have only established speed-concentration relations and have not considered the effect of time. If we wished to integrate the resnlting speed expressions, some differences would emerge. We should not inclnde a pseudo-steady state condition for an intermediate in order to deduce that its concentration (or amount) is constant in closed system. Similarly the integration of the speed equation cannot be performed in closed system if we do not know the law of the variation of the concentrations with time. 

This integration can be performed if the speed-concentration curve is transposed into rate-fractional extent curve. 

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