ความเข้มข้นของสารละลาย
Abstract Submicrorepresentations (SMR) could be an important element, not only for
explaining the experimental observations to students, but also in the process of evaluating
students’ knowledge and identifying their chemical misconceptions. This study investigated
the level of students’ understanding of the solution concentration and the process of
dissolving ionic and molecular crystals at particulate level, and identifies possible
misconceptions about this process. Altogether 408 secondary school students (average
age 16.3) participated in the study. The test of chemical knowledge was applied and the
analysis of four selected problems related to drawing SMRs in solution chemistry is
presented. Selected students were also interviewed in order to gain more detailed data about
their way of solving problems comprised in the knowledge test. The average achievement
on solution chemistry items was only 43%. It can be concluded from the results that
students have different misconceptions about arrangements of solute particles in the
solution and presentation of its concentration at particulate level. Students show quite low
achievement scores on the problem regarding drawing the SMR of ionic substance aqueous
solution (7.6% correct answers) and even lower ones on the problem regarding drawing the
SMR of diluted and saturated aqueous solutions of molecular crystal (no completely correct
answers). It can be also concluded that many different misconceptions concerning the
particulate level of basic solution chemistry concepts can be identified. In the conclusion
some implications for teaching