Upper school chemistry teacher Dr. Mala Raghavan’s Advanced Placement (AP) Chemistry class for juniors and seniors conducted their first in-class experiment of the year on Wednesday during periods two and four.

The lab, titled “Mass % of sodium bicarbonate,” took place as the second lab of the year and served as the first experiment conducted by the students since the first lab was an at-home worksheet. This experiment also met dual purposes by allowing students to practice lab skills for the first time this year and by helping seniors adjust to the chemistry lab setting since they all took a required chemistry course during remote learning two years ago when conducting labs was not possible except towards the end of the year for a couple labs. 

First, each pair of lab partners received a numbered vial containing a heterogeneous mixture, where the components are relatively separate, of sodium bicarbonate and sodium carbonate, the reactants of the experiment. The two compounds reacted to produce solid sodium carbonate as well as gaseous water and carbon dioxide. 

With 19 vials total, each vial contained a different value for mass percent that Dr. Raghavan recorded on a private spreadsheet. After recording the masses of the vial’s sample and the crucible, a ceramic container used for heating, students placed the two over a Bunsen burner. The crucible’s material, however, left it easily susceptible to high temperatures, causing fracturing, which raised some concern for Ishani Sood (11) and her lab partner.

“It was kind of funny when we realized that our crucible was cracked after we had already started the experiment, so we were scared that our data would be off,” Ishani said. “Thankfully, it lasted and didn’t crack.” 

Once the heating time finished, students allowed the crucible to cool for around five minutes before taking the mass of it. They repeated this process exactly, with the exception of heating for only three minutes, until the mass stopped changing. With all their data recorded, students finished calculating the mass percent of their respective bicarbonate answers at the end of the experiment. Each group then checked with Dr. Raghavan to determine the accuracy of their value. 

“It was a fun activity,” Ishani said. “Although it wasn’t a complicated experiment, it was a good jump back into practicing lab skills and working in a lab.”