Measuring Absorbances

Measuring the Blank

To blank the spectrometer, fill a cuvet with solvent and place it in the cuvet holder.  Most modern instruments have a specific button or procedure for the blanking process.  Usually this involves measuring a spectrum of the solvent, then subtracting that spectrum from any future measurements.  Because of this, if you continue to measure the absorbance of ethanol after measuring it as blank, the spectrum should measure ~0 absorbance at all wavelengths.  This is a good way to check that the SpectroVis is blanked properly.

Measuring Calibration Solutions

To measure the spectrum of the calibration solutions, simply remove the cuvet from the previous measurement (blank or sample) and place the cuvet of interest in the SpectroVis, which will obtain a new spectrum.  If you were using a SpectroVis in person you would be able to pause the collection process to find the wavelength at which your sample has the maximum absorbance, λmax.  Instead, this website will provide you with the spectrum as well as a corresponding data file (.xlsx or .csv).

Not familiar with .xlsx or .csv files?  Click here to learn more!

Student Data

If you are completing this experiment fully online, please use the data from the group associated with the first letter of your last name based on the list below.  Be sure to write down your assigned group number in your notebook.

A-D: Group 1
E-H: Group 2
I-L: Group 3
M-P: Group 4
Q-T: Group 5
U-Z: Group 6

Need help viewing your data in Excel or Google Sheets?  Click here for instructions!