Resumen

CORDOVA FRUNZ, José Luis et al. Reasons to focus in ratios. Educ. quím [online]. 2010, vol.21, n.1, pp.33-39. ISSN 0187-893X.

Concentration of solutions is a fundamental subject in chemistry, which requires understanding and handling the ratio and proportion concepts. In order to identify the level of understanding these concepts, we designed and applied a collection of problems related to the use of different concentration units, to a population of first year chemical engineering students, whose procedures of resolution and results were analyzed. We observed that students have strongly rooted habits and that it is not possible that they adapt and classify their procedures to solve problems of greater complexity,despite being of daily context.In addition to errors and omissions, we could state that the fundamental concept of ratio and its immediate one, the proportion, represent difficulties and limitations for students when they are outside the algorithmic level.

Palabras llave : Ratio; proportion, solution; concentration; problem solving.