Visualización del concepto de concentración a través de un modelo analógico didáctico

Abstract

Students of different educational levels have difficulties on the subject of concentration of solutions after their teaching, even though they can arrive at correct answers in numerical exercises. Therefore, it is necessary that they have a qualitative knowledge based on appropriate mental representations, which goes beyond the handling of formulas and numbers. This article presents a preliminary experience, carried out with 26 first-year university students, in which the didactic analog model for concentration learning (MADCo) is put to the test. This model involves students in an active process of building a generic mental representation of concentration. The results obtained show that the students were able to understand the model and with it solve the different activities, since this representation allows to visualize the amount of solute dissolved in a volume of solution. The use of the model supported the construction of an adequate internal representation of the concept of concentration that interacts in situations that required reasoning such as: (a) simultaneously consider two extensive variables (amount of solute and volume of dissolution) and reduce them to amount of solute in one dissolution volume unit, (b) preservation the number of solute units in the event of certain changes such as the addition or evaporation of solvent, (c) preservation of the dissolution volume in the event of changes such as the addition or extraction of solute.