We frequently talk with teachers who wonder if they should invest in a spectrophotometer or if they can run an experiment successfully with the more affordable Colorimeter. Let’s compare the two devices to clarify these options.
A spectrophotometer can be set to measure % transmittance or absorbance over a wide range of wavelengths. For example, the wavelength range of the SpectroVis Plus Spectrophotometer is 380 nm to 950 nm, and the wavelength interval is approximately 1 nm between reported values. In comparison, the Vernier Colorimeter can measure % transmittance and absorbance at four specifc wavelengths (430, 470, 565, and 635 nm) produced by internal LEDs.
Many of the same experiments will produce valid results on either device. For example, if you are doing an experiment based on Beer’s law (absorbance vs. concentration), both devices will give you a direct relationship between the absorbance value and the concentration of the standard solutions. Subsequent determination of the concentration of an unknown solution, based on the standards, will produce similar results.
Deciding to purchase a colorimeter or a spectrophotometer depends on the types of experiments in your curriculum. A spectrophotometer is compatible with all the spectroscopy experiments in the Vernier chemistry lab books. Several of those same experiments include instructions for use with a colorimeter. Many of the AP* chemistry lab experiments from the College Board emphasize the importance of a spectrophotometer’s ability to measure a full absorbance or % transmittance spectrum.
|Wavelength options||380 to 950 nm||430, 470, 565, 635 nm|
|Absorbance vs. concentration||Yes||Yes|
|Absorbance vs. time||Yes||Yes|
|Absorbance vs. wavelength||Yes||No|
|Connection type||LabQuest interface and computer USB port||LabQuest interface and Vernier computer interfaces|
Vernier offers a range of affordable educational spectrophotometers.
* AP and Advanced Placement Program are registered trademarks of the College Entrance Examination Board, which was not involved in the production of and does not endorse this product.