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Plasmonic Evolution and Arrested Development for Silver Nanoscale Colloids: A Classroom Demonstration
摘要： A vivid demonstration visualizing the colloidal behavior of silver nanocrystals is described. An aqueous?ethanol silver ion solution becomes yellow upon initial chemical reduction (using sodium borohydride, NaBH4), which is followed by chromatic evolution to orange, red, violet, and ?nally blue over the course of approximately 3 min because of the predictable growth and evolution of the nanocrystals. This undergraduate-level classroom demonstration is useful for illustrating the protective e?ect of a passivating ligand, such as polyvinylpyrrolidone (PVP), by showing the ability of PVP to halt the growth and coalescence of silver colloids at a desired stage, arresting the color transition at a particular hue. This demonstration can also be extended to highlight the bifurcated impact of such passivation on colloid behavior (e.g., improved long-term colloid stability coupled with worsened nanocatalytic performance).
关键词： First-Year Undergraduate/General,Inquiry-Based/Discovery Learning,Colloids,Second-Year Undergraduate,Demonstrations,Metals
更新于2025-09-16 10:30:52
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Production and Evaluation of a Realistic Immersive Virtual Reality Organic Chemistry Laboratory Experience: Infrared Spectroscopy
摘要： Using virtual reality (VR) in educational settings is becoming increasingly popular. The feasibility of replacing an instrumentation-based organic chemistry lab with a VR experience has been evaluated. A VR laboratory experience was designed to teach students how to use an infrared spectrometer and elucidate an unknown structure from the resulting infrared spectrum. The resulting first-person VR experience is immersive and realistic, with a teaching assistant guiding the user along the steps required to complete the experiment, including feedback as needed. The VR experience was developed in WondaVR with selections made using gaze navigation. The resulting product was tested with a group of students, and the outcomes for short- and long-term recall were compared with a group of students that did the same experiment in a traditional lab. Results indicate that there are no significant differences in learning outcomes between the two groups, which indicates the possibility of using this tool to offer this organic chemistry lab experiment via distance education. Students that tried the VR experience reported a high degree of satisfaction with the product and no significant usability barriers. These VR experiences could be useful for students who are unable to be present in lab due to disabilities, attendance challenges such as pregnancy, or safety concerns.
关键词： Second-Year Undergraduate,Laboratory Instruction,Multimedia-Based Learning,Computer-Based Learning,Distance Learning/Self Instruction,Instrumental Methods,Student-Centered Learning,Organic Chemistry
更新于2025-09-12 10:27:22
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Exploring the Gel State: Optical Determination of Gelation Times and Transport Properties of Gels with an Inexpensive 3D-Printed Spectrophotometer
摘要： The study of gels and their properties is a compelling topic both technologically and scienti?cally, and should therefore be emphasized in chemistry and material science syllabuses. In the present laboratory experiment, we propose two experiences, aimed at introducing gelation and gel transport properties using silica gels made from sodium silicate and sodium citrate bu?er. In particular, gelation times are used to teach kinetics and optical properties to ?rst and second year General Chemistry students. Gelation times are determined by measuring the increment in scattering intensity with a 3D-printed spectrophotometer. The gel transport properties are presented to further exemplify Fickian and non-Fickian behavior through ionic dyes di?using in gels. A qualitative description is obtained from charge interactions, and a quantitative description utilizing the di?usion coe?cient is achieved by analyzing absorbance pro?les. These tasks were designed to encourage students to work with unusual topics in a holistic way, approaching new materials, properties, and DIY equipment. Blueprints for the spectrophotometer, resources for instructors, and a detailed students’ guide are provided together with a short report model to promote critical discussion of the observations.
关键词： Transport Properties,Physical Chemistry,Materials Science,Second-Year Undergraduate,Hands-On Learning/Manipulatives,First-Year Undergraduate/General
更新于2025-09-09 09:28:46
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A Simple Synthetic Approach To Prepare Silver Elongated Nanostructures: From Nanorods to Nanowires
摘要： A procedure for one-pot preparation and characterization of silver 1D nanostructures is described. The main advantages of this synthetic approach are the simplicity and reproducibility, where the size of the final product can be controlled just by changing the reaction time. This experiment is designed as a laboratory introduction to colloidal chemistry for undergraduate and graduate students; they can appreciate the role of the different reagents in a relatively complex reaction and understand the relation between the morphology of a metal at the nanoscale and some macroscopic properties, such as its visible absorption spectrum (i.e., color).
关键词： Nanotechnology,Synthesis,Second-Year Undergraduate,UV?Vis Spectroscopy,Physical Chemistry,Laboratory Instruction,Hands-On Learning/Manipulatives,First-Year Undergraduate/General,Metals,Colloids
更新于2025-09-04 15:30:14