Laser-pointer spectrometry revisited: Application of light sensor and data acquisition device

CHED 350

Shannon V. Wallen, wallens@etown.edu and Kristi A. Kneas, kneask@etown.edu. Department of Chemistry and Biochemistry, Elizabethtown College, One Alpha Drive, Elizabethtown, PA 17022
The construction, applicability, and functionality were investigated for a laser-pointer-based spectrometer which has as its detector a commercially-available light sensor used with a LabPro or LabQuest data acquisition device and Logger Pro Software (Vernier). Results obtained when the spectrometer was used for endpoint detection in EDTA titrations to determine water hardness were compared to those obtained using the visual indicators Eriochrome Black T and Calmagite. The advantages of this spectrometer, which include unambiguous end point detection, real-time acquisition of the titration curve using Logger Pro software, and ease of set-up resulting from elimination of an in-house-built photoresistor circuit are discussed, as is the feasibility of its use in the teaching laboratory.