How do buffers resist changes to pH?

Abstract

Level: Undergraduate/adult

Setting: Classroom

Activity Type: Learning Cycle

Discipline: Chemistry

Course: Modified GOB chemistry

keywords: buffer, buffer capacity, weak acid, conjugate base

Abstract

The GOB chemistry course is part of a biomedical workforce development program for adults with a wide range of backgrounds.  A significant number of students have not studied chemistry before, or have a very basic middle school level.  In the laboratory, students will learn to make biological buffer solutions, adjust the pH of a buffer solution by addition of acid or base, and utilize the concept of buffer capacity.

This POGIL activity provides the students with a conceptual understanding of what is happening to the buffer upon addition of acid or base and why the buffer solution shows a smaller change in pH than a solution without any buffer.  The particle diagrams are adapted from a tutorial created by Chem Collective: http://chemcollective.org/activities/tutorials/buffers/buffers1