P750a: Twist on solubility lab to prepare for Ksp math concepts

Author: Deborah Rosenthal, Washington State Community College, USA


Date: 8/6/14

Time: 9:55 AM10:05 AM

Room: MAK B1120

Related Symposium: S57

I was asked to develop and teach a lab for a high school group visiting our community college for an afternoon; STEMM initiative. I wanted to do a lab that was related to their daily lives and focused on a concept I felt needed more attention. Teaching solubility usually involves an all-or-none concept or using math to utilize the solubility product constant. In the health science field chemistry students usually encounter a lab of mixing two chemicals to determine whether or not a precipitate will form. In the pre-professional track mathematical problems are practiced. I developed a non-mathematical laboratory experiment to show students that solubility depends on the chemicals mixed AND the concentration. A short yet creative PowerPoint presentation was given concerning kidney stones. It began with showing pictures of famous people that had kidney stones. It ended with an explanation of kidney stones formation and treatment. Of course, one of the main points was that drinking water could help prevent kidney stones. In the lab students mixed various chemicals to see if a precipitate was formed. The difference in this lab from a typical introductory solubility lab was that the students had to quantitatively dilute each chemical until they determined how much dilution it took so no precipitate was formed from the same chemicals. A range of chemical pairs can be used, but it is best to pick ones that have a range of Ksp values.

P92: Improving lab reports through alternative activities

Author: Deborah Rosenthal, Washington State Community College, USA


Date: 8/3/14

Time: 2:25 PM2:45 PM

Room: MAK B1114

Related Symposium: S14

Students transferring from a community college to a large four-year institution may encounter difficulty in the transition. Their chances of being successful in upper-level chemistry courses will be increased if they have the skills to write formal lab reports. The opportunities for individual guidance in scientific writing are easier to provide in smaller class settings. Writing formal lab reports and constructive feedback is considered beneficial. A common practice is supplying a list of components and explanations for lab reports followed by instructor feedback. Additional activities of having students evaluate peer-submitted lab reports, altered or rearranged components of journal articles in order to identify common mistakes helps them to understand the correct components of scientific writing. Students were asked to write lab reports during the first semester. Despite constructive comments the lab reports continued to contain the same errors. Lab reports were submitted the first half of the second semester and common errors were recorded. Hands-on activities were conducted in class to address the specific errors. The lab reports were evaluated during the second half of the semester to see if major improvements were made in the areas addressed.