Cambios químicos y conservación de la masa... ¿Está todo claor?

Resum

In this paper the authors present results obtained along three years in evaluations made to the students entering the first Chemistry course in the Buenos Aires University, referred to the law of conservation of matter and the concept of chemical change. These results, which are similar to those obtained by other investigators in different countries, show the difficulties which still remain after middle school education, that should worry educators and move them to change their way of teaching such concepts, which are essential for a proper chemical knowledge.