Teaching Spectrophotometry and Graphing Using Red Cabbage Extract and pH Buffers

 

Frances Kennedy

Tested Studies in Laboratory Teaching, 1994, Volume 15

Abstract

Since students often come to an introductory science course with an insufficient math or science background, we found it useful to teach an exercise where students generate data that they use to construct a table and graph. Cabbage anthocyanins change color at different pH values and we introduce students to this effect of change of pH on these pigments. We also teach use of the Spectronic 20 spectrophotometer as a means of data acquisition, in this case with regard to the electromagnetic spectrum and visible colors. This exercise is performed early in the semester as preparation for later discussions and experiments regarding the effects of changes in pH relative to the action of enzymes during metabolic processes.

Keywords:  spectrophotometry

University of Toronto (1993)