From Redox Reactions to Nanomaterials: Visual Lab Activity for Exploring the Stabilization and Aggregation of Silver Nanoparticles

This study proposes a lab experiment consisting of three consecutive steps designed to expose undergraduate students to the fundamental aspects of nanoscience. Two different procedures for the reduction of silver ions were provided: The first resulted in a precipitate, and in the second reaction a colored suspension of silver nanoparticles was obtained. Next, the students explored the aggregation process of silver nanoparticles by converting one solution to the other, which produced interesting color changes. The present discussion centers on the role of this lab activity as a visual means to introduce students to basic concepts related to nanomaterials: metal nanoparticles, colloidal suspension, colloid stability, surface plasmon resonance of metal nanoparticles, zeta potential, electric double layers, and the aggregation process. The experiments were carried out by a group of second-year college students majoring in chemistry.