La comprensión de estudiantes de primer año de universidad del concepto de concentración expresada en gramos por litro

Abstract

As an approach to the learning of the concentration of solution concept, the article discusses literature from different perspectives, including results from the mathematics education field. Main focus is on the concentration in the concept of grams per liter. Learning the concept of concentration in g/L as a problem has not been previously addressed in the literature. The research applied the «Reasoning with concentration grams per liter» questionnaire to 140 Argentinian freshmen students. The questionnaire asks students to think about logical-mathematical relationships between the variables m, V and Cg/L. A discussion from questionnaire results follows. In addition, 18 students participated in think-aloud interviews about the items of this questionnaire. Results from the questionnaire and the interviews show that more than half of the freshmen students do not have a deep conceptual knowledge about concentration in g/L. The main difficulty lies in inverse proportionality tasks: when students must qualitatively relate the solute mass (extensive) and the Cg/L (intensive), in order to determine which solution occupies a smaller volume.