Grade 10 and 11 Thai Students' Conceptions about Stoichiometry

Abstract

     Stoichiometric concept is one of the fundamental and important concepts of chemistry subject, especially in quantitative chemistry. This study explores 97 Grade 10 and 11 Thai science students who had learned stoichiometry topic in three public schools in Bangkok by using a purpose designed questionnaire - the Stoichiometry Concept Questionnaire (SCQ). The SCQ consists of 16 multiple choices questions and respondents are required to provide reasons for their choices. The results suggest that many students hold alternative conceptions about stoichiometry which in line with studies carried out in other countries. The main student alternative conceptions are to do with atomic mass or molecular mass, which students think is the mass of one atom. The students also thought that one mole of all substances has a volume of 22.4 L at STP, and that a solution that contains a greater amount of solute has the higher concentration. Students think that the limiting reagent is the reagent for which the lowest mass of reactant is present. These alternative concepts are useful for teacher to improve their teaching.