This work determined the previous ideas and the conceptual difficulties that the eleventh grade students of the San Pablo Educational Institution in Pueblo Rico, Risaralda have in understanding stoichiometry and underlying concepts; data collected through a mixed categorized questionnaire (open and closed questions) self-administered through the website. The project is a non-experimental descriptive transactional design with a mixed approach. The results obtained were used as input to design a didactic macro sequence, that is, a sequence composed of subsequences, whose intention is to contribute to improving the teaching and learning of stoichiometry. This macro sequence is based on the methodology of Problem Based Learning (PBL) through the Maastricht seven-step technique that includes conceptual, procedural and attitudinal contents, as well as various types, techniques and evaluation instruments. The internal dynamics of the didactic sequence under the PBL approach offers great possibilities for improving the stoichiometry learning process because, by employing contextualized problems and studying them in a logical, sequential and coherent order, it contributes to the significant learning of the concepts by showing students the usefulness and importance of the information provided and by promoting the development of thinking skills through the activation of cognitive processes that generate intellectual action.