This study investigated the students' misconceptions of the solubility equilibrium. The participants of the study consisted of 168 students who were in the science class of second year high school. Instrument used is two-tier diagnostic test consisting of 15 items. Responses were marked and coded into four categories: understanding, misconception (false positive), misconception (false negative), and misconception. Semistructured interviews were carried out with 45 students according to their written responses which reflected different perspectives, to obtain a more elaborated source of data. Data collected from multiple methods were analyzed qualitatively and quantitatively. Based on the data analysis showed that the students misconceptions in all areas in solubility equilibrium. They had more misconceptions such as in the relation of solubility and solubility product, common-ion effect and pH in solubility, and selective precipitation.

Keywords: misconceptions; two-tier diagnostic instrument; solubility equilibrium.