Apologia Chemistry Module Eleven Solubility

The Apologia chemistry textbook, Experiment 11.2, The Effect of Temperature on the Solubility of a Gas gave me an idea for an inquiry-based lab.  Last fall, a fifth grader at WA, Julia, wanted to test her hypothesis that hot soda goes flat faster than cold soda.  I was helping the fourth and fifth graders understand the science fair process.  When Julia explained her idea, it occurred to me that I had a CO2 sensor, part of a set, a Pasco rep. had given me after a conference which I had never used.  Ever. Julia and I were able to trouble shoot the apparatus.  Now, that I have learned the quirks of my Sparklink interface, I have lost most of my inhibitions about tackling new sensors.  Here are some screen shots and a photo.

In any case, Experiment 11.2 can be adapted to an inquiry based lab, using CER, claim based evidence.  In other words, we used Julia's science fair project to examine gas solubility in solution.  My Chemistry kids spent some time discussing gas solubility with a coke can as a prop.  Once the kids could articulate that carbon dioxide gas would fizz faster from a warm can of soda than an ice cold can, they were ready to start.  I demonstrated the CO2 sensor, took it completely apart and made them reassemble it and connect the iPad with its app to the Sparklink.  Then they brainstormed ideas. I made a few suggestions, such as using the same container for the bath and creating a room temperature water bath instead of testing one outside of a water bath.  When they asked what room temperature was, I pointed to the temperature probe collecting data.  I also had to ask them how long would they collect data and how long would they allow their cans of soda to equilibrate.  Once completed, the kids wrote a formal lab report.  They are finishing these for homework. Before, during, and after the lab, I asked the kids a few questions: What is the purpose?  What are potential sources of error?  How does gas solubility change with temperature?  The kids should answer these in their labs.  Just as a review, for me a standard lab report has a title, purpose, materials, procedures, data, discussion, and conclusion.  A standard conclusion is that more trials are indicated.

This lab provides an opportunity for CER, claim-evidence-reasoning.  This CER example provides a model.  For this experiment, the claim is that gas is least soluble in very hot water and most soluble in a solution which is very cold.  The dissolved oxygen concentrations are highest on a cold winter day. The evidence for this claim is that a can of soda in very hot water produces more CO2 than a can of soda in ice water.  The reasoning has to do with the gas solubility in solution or more gas remains dissolved in solution in icy water than in boiling water.   CER requires logic and critical thinking.  Kids hate this process.  It's hard work.  I love CER.  Here is a process to get kids to think through a project and articulate their findings.