Using New AACT Resources to Help Teach Acid Base Chemistry

As chemistry teachers plan activities for their students, AACT will highlight resources from our high school library that help to reinforce topics in different units throughout the school year. Our last news post highlighted resources from our high school library that support an Equilibrium unit. We will now focus on lessons and other activities for an Acid Base Chemistry unit.

Since our original post in May 2018 and follow-up post in March 2019, we have added and updated a few resources that you might consider trying with your students. Additionally, we have a unit plan that uses many of our resources to help you teach a unit on Acid Base Chemistry. In this post, we are going to highlight some of our most “Favorite” acid base resources.

Introduce the unit with the Acid & Base Guys video which tells the story of how the definition of acids and bases evolved from Lavoisier’s hypothesis. Starting with the idea that acidity is caused by oxygen atoms, to Arrhenius’s definition of an acid as a producer of positive hydrogen ions, then changed to acids as proton donors by Bronsted and Lowry, finally switching to acids as electron acceptors by Lewis. Have your students use the Acid & Base Guys Video Questions activity to answer questions while watching the video.

Depending on the math level of your students, you may want to use the lesson plan, Calculating pH, A Look at Logarithms to introduce the math concepts involved in the study of acids and bases. In this lesson, students are introduced to a base-10 logarithmic scale and use it to calculate pH from hydrogen ion concentration. Often students are able to calculate pH by pushing the correct buttons on their calculators, but they don’t understand what the values mean. This lesson attempts to bridge that gap using a guided inquiry model.

Follow up with the lab, Exploring the Properties of Acids and Bases to investigate the properties of many household substances and discover the properties of acids and bases in this five station activity.

Introduce acid-base calculations with the lesson plan, Categorizing, Calculating and Applying Concepts from Weak Acids, Weak Bases and Salts. Students will first write dissociation reactions to make connections between conjugate acid-base pairs. They will then use beaker diagrams in a cooperative group activity to better understand why the pH calculation for a weak acid/base is not the same for a strong acid/base. Finally, students apply these concepts in a lab in which they will identify several unknown, clear, colorless solutions using factors such as pH, conductivity and reactivity. The activities within this lesson can be used in sequence or as standalone activities and include alignment with AP Chemistry Units, Topics and Learning Objectives.

If you like to encourage your students to connect chemical principles to everyday life, use The Egg-straordinary Issue lab to have your students determine the percent composition of calcium carbonate contained in an eggshell by using a back titration in order to address a farmer’s concerns about his hen’s fragile eggs. Two versions of the student lab are included, a scripted version, and an inquiry version. Another choice might be using the lab, Calculating Acid in Lemon-Lime Soda to have them investigate the molarity of citric acid their favorite lemon-lime flavored soft drink through titrations with 0.10M NaOH and an indicator.

For those of you who have more advanced classes, use the lesson plan, Preparation and Evaluation of Buffers to have students use multiple methods to calculate and prepare buffered solutions with a desired pH. Upon preparation of the solutions, the students will explore differing aspects of buffers including buffering capacity and predominant form.

At the end of the unit, use the Milk of Magnesia Magic demonstration to help students see the connections between acid-base chemistry and stoichiometry, limiting reactants, Le Châtelier’s principle, indicators, and buffer solutions. This resource includes alignment to the AP Chemistry Units, Topics and Learning Objectives.

We hope that these activities can help you to reinforce several of the topics covered in a unit about Acid Base Chemistry. Most of these lessons were made possible by great teachers who shared their own resources. We need your help to keep the collection growing. Do you have a great demonstration, activity, or lesson related to this topic that you would like to share with the community? Please send it along for consideration.