The study of gels and their properties is a compelling topic both technologically and scientifically, 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 buffer. In particular, gelation times are used to teach kinetics and optical properties to first 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 diffusing in gels. A qualitative description is obtained from charge interactions, and a quantitative description utilizing the diffusion coefficient is achieved by analyzing absorbance profiles. 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.

中文翻译：

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探索凝胶状态：用廉价的3D打印分光光度计对凝胶化时间和凝胶的传输性质进行光学测定

凝胶及其性质的研究在技术上和科学上都是一个引人注目的主题，因此在化学和材料科学课程大纲中应予以强调。在当前的实验室实验中，我们提出了两个经验，旨在介绍使用由硅酸钠和柠檬酸钠缓冲液制成的硅胶的凝胶化和凝胶运输特性。特别地，胶凝时间用于向一般化学大一和二年级的学生传授动力学和光学性质。胶凝时间是通过使用3D打印分光光度计测量散射强度的增量来确定的。提出了凝胶传输性质，以进一步举例说明通过在凝胶中扩散的离子染料的Fickian和非Fickian行为。从电荷相互作用获得定性描述，通过分析吸光度分布图可以得出利用扩散系数的定量描述。设计这些任务是为了鼓励学生以全新的方式使用新材料，新特性和DIY设备来处理不寻常的主题。提供了分光光度计的蓝图，讲师的资源以及详细的学生指南以及简短的报告模型，以促进对观察结果的严格讨论。