The origin of this activity stemmed from myself graduating with a degree in chemistry, without ever calculating or making a 1.0 M solution. I felt that this was a disservice to myself, and vowed that my students wouldn’t have the same experience.
We entered the solution chemistry unit with the goal of using Ward’s Data Hub, new instrumentation at the high school, for the first time. I generated a lab over fall break that allowed both my personal goal, as well as clinical faculty’s, to meld into a singular laboratory activity.
Students were asked to calculate how to make a 1.0 M NaOH solution, then requested to make it using appropriate glassware. Next, they were asked to perform a dilution calculation and then generate a dilution from the stock solution that they initially made using appropriate glassware. The students were then asked to calculate and make a second dilution of the stock solution, similar in method to the second solution they made. Finally, the pH probe of the Data Hub was used to check the pH of each solution to ensure that they were made to the correct concentrations.
Even with a well written explanation, and with correct calculations, students struggled with the confidence that they could actually make a given solution. They were much more confident with dilutions, even though it was the first time that they had used pipettes. I like how well integrated the concepts of molarity, dilution, and pH are in this lab, and plan to use it in again in my own future classroom.
InTASC standards 3-4-5-6-7-8 were all covered during this lab though the planning, implementation and execution of it. HLPs 2-5-6-11-13-14 were also incorporated throughout. I spent the better part of fall break generating this lab, and really poured a lot of effort into it. It always amazes me how long it takes to generate an activity from scratch, and how quickly errors are found in it once it is put to use. This is a great way to obtain instant feedback to improve activities, however.