Equilibrium

In the January 2025 APTeach presentation, we explored how to address common student misconceptions related to chemical equilibrium as well as ideas for engaging activities and labs to strengthen student comprehension. View the video summary and the presentation slidedeck.

Abstract: This post describes a simple device used to demonstrate and clarify some challenging concepts in thermodynamics at the General Chemistry level.

Co-Authored by Dean J. Campbell* and Ali Patel* *Bradley University, Peoria, Illinois

An experiment that has always fascinated me is observing what happens when CO₂ is bubbled into limewater (which is a saturated solution of calcium hydroxide).^1-2 This experiment can be carried out by blowing bubbles of exhaled breath (which contains roughly 4% CO₂)³ through a straw into limewater.

We typically teach students to solve qualitative chemical equilibrium problems using an ICE table, where I, C, and E represent [Initial], [Change], and [Equilibrium] concentrations of each reactant and product in units of mol∙L^–1. At the risk of insulting you, I’ll provide an example, liberated from our class textbook:¹

Q, K, ∆G and ∆G°.

Co-authors: Rachel Barnard*, Samantha Cass, and Ryan Sweeder (*: corresponding author) Lyman Briggs College, Michigan State University

Bottles of soda are sealed under high pressures of CO₂, or P_CO2. This causes a substantial amount of CO₂ to dissolve into the beverage, giving the drink its fizziness. But what exactly is the pressure inside a bottle of soda?

If you know me, you know that I love the Diet Coke and Mentos reaction. It’s so simple to carry out, but yields incredible results! Just drop a few Mentos candies into a bottle of a carbonated beverage and watch the magic take place! See video 1.

In Chemical Mystery #17, shavings of Dial soap are added to samples of Aquafina and Evian drinking water. Upon blowing into each mixture with a straw, only the Aquafina water produced stable bubbles. Why is this the case?