Taking the Hassle out of Hasselbalch

Mention pH in a classroom and you can almost see the inner yawn on the faces of your students. The definition may even roll easily from their lips. However, despite multiple exposures to the relationship of pH and pKa throughout a typical undergraduate science curriculum, students struggle to differentiate between a property of a molecule (pKa) and the impact of molecules, such as acids and bases, on the environmental conditions (pH). Even fewer are comfortable applying their knowledge to predict the effect of environmental pH on the ionized status of functional groups in biologically relevant molecules, groups that are behaving as weak acids and weak bases. The approach of this lesson is to review this foundational topic from an intuitive angle first and then connect qualitative to quantitative reasoning. It progresses through a series of clicker questions that are used to facilitate peer instruction in small groups. The clicker questions are structured by mini-lectures that provide support for the "math phobic"; therefore, this sequence is also suitable as a group work-sheet activity. This lesson is intended for an introductory biology or chemistry course, but can be adapted and expanded for advanced students to explore medical and pharmaceutical applications.

提及pH值于课堂之中，几乎能够洞察学生脸上流露出的淡淡困意。虽然pH的定义对他们而言或许唾手可得，然而，即便在典型的本科生科学课程中多次接触到pH与pKa之间的关系，学生们仍难以区分分子性质（pKa）与分子（如酸和碱）对环境条件（pH）的影响。更少的学生能够自信地将所学知识应用于预测环境pH对生物相关分子中功能基团电离状态的效应，这些基团作为弱酸和弱碱发挥着作用。本课程的教学方法首先从直观角度回顾这一基础主题，接着将定性分析与定量推理相结合。通过一系列的抢答问题，旨在促进小组成员间的同伴教学。抢答问题通过微型讲座进行结构化，为对数学感到畏惧的学生提供支持；因此，这一序列亦适用于作为小组工作表的实践活动。本课程旨在为初学者生物或化学课程设计，但可根据需要进行调整和扩展，以便高级学生探究医学和制药应用。