Throughout the last ten years teaching both chemistry and Advanced Placement Chemistry I have realized that the concept of equilibrium does not receive enough attention in my first-year chemistry course. Sure, the concept of equilibrium is a topic mentioned and identified throughout the course however the dialogue in regards to conditions that would shift the chemical system is minimal at best.
In the past, I have used simulations involving objects, such as coins or paper clips, to determine equilibrium constants however I have to wonder if the students really understood the big idea these manipulatives were supposed to represent. In addition I find that most students can define Le Châtelier's principle however struggle when asked to explain why shifts in the chemical system occur.
In addition I have noticed that students have misconceptions about reactions before they arrive in first-year chemistry courses. For many, they developed the misconception that once something experiences a chemical change then the reaction is ‘complete’. In fact I have heard numerous students refer to all reactions as irreversible.
As I reflect on both my own curriculum as well as student misconceptions it is obvious that I need to include more evidence on how conditions of a chemical system can change and therefore cause a shift in equilibrium. Although this is a concept that is regularly addressed in an AP class, how is it meaningfully incorporated into a secondary chemistry classroom?
With many states recently adopting the Next Generation Science Standards, many teachers may have to redesign their curriculum as the standards place an emphasis on rates and equilibrium. In fact, two of the eight standards regarding matter and its interactions involve student comprehension of reaction rates and equilibrium. Although students are not required to calculate any equilibrium constants and/or concentrations they do have to recognize and explain the outcome of changing a chemical system.
Despite whether or not your state has adopted NGSS, my question that I would like to build a dialogue around is: What do you do in your class to introduce and develop the concept of equilibrium?
Please feel free to comment below and provide any student feedback, if available.