Fading phenolphthalien kinetics experiment employing a diode array based spectrometer

CHED 427

Nwamaka I. Ifionu, ronald.fietkau@gcsu.edu, Whitney L. Sheppard, and Ronald Fietkau, ronald.fietkau@gcsu.edu. Department of Chemistry & Physics, Georgia College & State University, 231 W. Hancock St., Milledgeville, GA 31061
Phenolphthalein is commonly found in instructional laboratories most often used as an indicator in acid-base titrations to show the endpoint. An interesting fact about phenolphthalein is that in basic solution the pink color fades with time. This observation has been used to illustrate pseudo-first-order-kinetics. This experiment employs a diode array based spectrometer and its software to collect the absorbance of phenolphthalein at 550 nm as a function of time. The results are exported to a spreadsheet for further processing.