A THERMODYNAMIC MODEL TO TEACH CHEMICAL EQUILIBRIUM

Chemical Equilibrium is a central concept in the learning of chemistry and remains one of the most difficult to teach and to learn. Therefore, this topic is the subject of many studies in science education with different goals: to know the difficulties of student learning, misconceptions, explanations for these errors, and so on.
Traditionally, the teaching of this concept is parallel to the Le Chatelier principle (LCP) and science education research have shown how, apparently reasonable applications of LCP, can result in incorrect predictions about the effects of changes in concen¬tration, volume, pressure, or temperature on chemical systems at equilibrium. On the other hand, the construction of this concept is based on kinetic arguments that have not been deducted or explained.
The students must establish meaningful relationships between chemical theories, practical activities (to perform their experiences) and languages with which to be expressed about them; but it is the teacher, with appropriate teaching, who should facilitate them to do this in a meaningful way. Therefore, in this work we present a teaching-learning sequence built in the framework of School Science, to proposes the construction of a Chemical Equilibrium model based on thermodynamic (phenomenological) arguments and, in agreement with constructivist theories, we take as a starting point the alternative conceptions, prior knowledge and the various cognitive abilities of the students. Our hypothesis is that in this theoretical framework, the students can construct the concept in a better manner.