Le Châtelier's Principle

The conversion of adenosine triphosphate (ATP) into adenosine diphosphate (ADP) is an extremely important energy source for living organisms. Under common physiological conditions, it can be expressed as:

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

A popular method for demonstrating the effect of temperature on chemical equilibrium involves the use of Co²⁺ complexes.

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.

I’d like to describe a very colorful system you can use to explore many facets of chemical equilibrium.

It is time for us as chemistry teachers to move beyond the Le Châtelier Principle as justification for why disturbances to equilibrium systems cause particular “shifts”.

Teachers are accustomed to implementing new learning standards developed by state or national leaders. My state, Georgia, chose not to adopt the newest national standards. State leaders wrote the “Georgia Standards of Excellence” instead. Full implementation of the GSE begins in the 2017-2018 school year.