Deciphering the Concept of Solubility by Strategically Using the Counterion Effect in Charged Molecules

Solubility is an essential concept in chemistry that describes the ability of a substance to dissolve in a particular solvent. Despite its importance in many fields of science, understanding the basic principles of solubility is challenging for many undergraduate students. Notably, students often encounter difficulties in comprehending the role of counterions when dealing with charged molecules. Here, we bring the opportunity to assimilate the key concepts of solubility regarding the role of counterions by developing a straightforward, cheap, and visually appealing experiment that focuses on the strategic use of counterions to control solubility. A student questionnaire delivered encouraging results with most of students giving positive feedback in both interest and training their hands-on skills. Hence, our experiment offers a proficient understanding of the solubility concept, thus preparing undergraduate students for advanced courses in the various subject areas of chemistry.