# Michael Stapleton

## Geography, Geology and the Environment

## Slippery Rock University of Pennsylvania

## Materials Contributed through SERC-hosted Projects

### Activities (2)

Introduction to Carbonate Equilibrium part of Cutting Edge:Hydrogeology:Hydrogeology, Soils, Geochemistry 2013:Activities

The activity asks students to make observations about what occurs when two effervescent antacid tablets are placed into a beaker of water. The Students work together in groups. There are three parts to the activity. In the first part, the tablets are dropped into tap water and student groups (2-4 students) must complete a series of question sheets (one per group) that guide them through thinking about the event. In the second part, a presentation on chemical equilibrium for the carbonate system is given. The starting point is the answers received in the first part. Basic chemical reactions for the carbonate system are presented including equilibrium expressions for each reaction and discussion about open and closed systems. At the end of class, a handout is given to the students. In the third part, three beakers (acidic, neutral and basic solutions, but not indicated) are placed together and two tablets are placed into each beaker. Students are split into two groups (8-12 students) and are asked to describe why the reactions are different. Discussion follows collection of student responses in each part. Once the chemical reactions and equilibrium expressions are presented, they are involved and referenced in all discussions.

Learn more about this review process.

Weak Acid Equilibrium part of Cutting Edge:Hydrogeology:Hydrogeology, Soils, Geochemistry 2013:Activities

Students are asked to calculate the pH of a weak acid aqueous solution. The problems involve a series of generic acids with assigned equilibrium constants (Ka) and total concentrations (Ct). Initially, students are required to hand calculate all problems by algebraic manipulation of the mathematical relationships of the system. The solution is a cubic equation. Through a series of assumptions, the solution is simplified. The assumptions are based on the chemistry of the system given the Ka and Ct for the problem. The problems are then graphically solved. Ultimately, the students develop an Excel worksheet to solve the problems and a Bjerrum plot to display the speciation as a function of pH.

### Course

Geochemistry part of Cutting Edge:Hydrogeology:Hydrogeology, Soils, Geochemistry 2013:Courses

This course will provide a general overview of geochemical systems and their interactions among atmospheric, aqueous, and near surface environments. Complex subjects will be developed gradually beginning with the basics and building. The idea is to give you an understanding of the importance of chemistry in geological and environmental interactions.

## Events and Communities

Geochemistry 2005 Participants