titration/volumetric analysis

Using Visual BCA Tables to Teach Limiting Reactants

picture of materials and WS

A few months ago I was searching the internet, looking for a better way to teach stoichiometry to my pre-AP chemistry students. While my methods of dimensional analysis “got the job done” for most students, I would still always lose students and many lacked true understanding of what was happening in the reaction. I wanted to try something new that would promote a better chemical understanding. In my search for this elusive stoichiometry method, I came across Dena Leggett’s ChemEd X blog post entitled “Doc Save Everyone”, as well as other posts about BCA tables from Lauren Stewart, Lowell Thomson, and Larry Dukerich. 

Titration of an Esterification Reaction to Determine Equilibrium Constant

ChemEd X recently made a Call for Contributions soliciting input regarding the big ideas being put forth by organizations like AP. The first thing that came to mind was a lab I modified that is centered around making connections between topics. Admittedly, this lab is not a "big idea" per se. Rather, it's the big idea that students should be able to make connections between topics we study to solve problems. So in this blog post, I would like to share a lab activity that relies on these connections - between stoichiometry, esterification, equilibrium, kinetics, titrations and uncertainty of calculations. I will also share the resources I have created to support my students through the process of working through these calculations.

Time required: 

Three class periods

Day 1: setup of equilibrium mixture; roughly 30 minutes

Day 2: titration of equilibrium mixture (approximately 1 week after Day 1); roughly 60 minutes

Day 3: calculations; variable time required - typically 30-90 minutes depending on the student group