Concerning the perturbation of chemical equilibria, the control of variables and the predictions of subsequent evolution: discussion of a university entrance testing exercise

Abstract

In this study, it is discussed a problem that deals with the disturbance of a chemical equilibrium mixture. This problem corresponds to the last chemistry exam to access university. It is analysed the possible deficiencies in the statements of the related problems, particularly when checking if they control the variables involved. In this respect, we examine the difficulties that are associated to the capacity to make accurate predictions corresponding to the changes the equilibrium mixture experiences in different situations. This analysis allows to establish some recommendations on the particular cases where it should be appropriate to assess this issue in a pre-university level of Chemistry.