Balakrishnan Viswanathan^1,, Mohamed Shajahan Gulam Razul¹

Combustion analysis is typically taught within the context of molecular stoichiometry, in particular the study of empirical formula. This approach is rich in the history of chemistry and also relevant to current laboratory practice. However, the complexity inherent in the traditional approach is not suitable for beginning learners; what should be a rich context for exploring chemical connections has in effect been reduced to an algorithm to be memorized. It is proposed that combustion analysis be taught within the context of limiting reagents, as this represents an ideal situation (one reactant in limited quantity and the other in infinite quantity). Moving the pedagogical position of this topic from molecular stoichiometry to reaction stoichiometry reduces the complexity of the problem from four steps to two. More importantly, the proposed method makes it possible to harness the knowledge that students have acquired earlier in the course to solve a problem in a new context. In the new approach, students match coefficients (computed on the reactant side with unknown on the product side) to obtain the composition of the substance being combusted. It is expected that the connection to prior knowledge and acquired skills will help students achieve improved success when solving problems of this nature.

general chemistry, stoichiometry, combustion, limiting reagents, algorithms