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  Home > JCE Print > Journal of Chemical Education > Issues > 2001  > September  >
Information • Textbooks • Media • Resources
Computer Bulletin Board
Beer's Law Measurements Using Non-monochromatic Light Sources--A Computer Simulation
George C.-Y. Chan and WingTat Chan
Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, Hong Kong (PRC)
Cover
September 2001
Vol. 78 No. 9
p. 1285
Full Text
A basic requirement of Beer's law is that the light source be monochromatic. It is easy for students to understand that non-monochromatic light sources cause deviation in Beer's law plots. However, the extent of deviation as a function of bandwidth cannot be easily predicted intuitively. We used a simulation program to help students understand the effects of bandwidth of a non-monochromatic light source on the magnitude of the measured absorbance and the slope and linearity of the Beer's law plot. The program is written in a script language running under a spreadsheet program. Any combination of the four predefined hypothetical profiles (rectangular, Gaussian, Lorentzian and triangular) of light source and absorption peak can be used. The bandwidth and wavelength of the profiles can also be assigned arbitrarily. The apparent absorbance is calculated. The transmitted spectral profiles and the Beer's law plots are also generated and graphically presented on the screen. The program is a visual tool for students to appreciate the behavior of Beer's law measurements using non-monochromatic light sources. It is useful for discovery-based learning of the application of Beer's law in various spectrochemical methods.
Supplement
A detailed description of the model and its theoretical background, and LabTalk program source code are available.
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*  Citation
 Chan, George C.-Y.; Chan, WingTat. J. Chem. Educ. 2001 78 1285.
*  Keywords
 Analytical Chemistry; Computer Assisted Instruction; Numerical Methods; Quantitative Analysis; Teaching / Learning Aids
*  History
 Created:
Last Updated:		 August 14, 2001
August 31, 2005
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